Moonwards

Narrated Walk-through of the Equatorial Colony

noreply@blogger.com (Kim Holder) — Sat, 24 Feb 2018 20:10:00 +0000

A new 36 minute video has been posted here on YouTube, and is also now at the top of the video list at the bottom of the website's main page. In it I talk about the equatorial moon colony's radiation barriers, light funnels, heat radiators, moon stairs, and various other things. The colony was rendered with realistic lighting to really get across the tremendous impact of having a glazed roof that also protects against radiation. The 3d model now has a digital sky containing a sun that lights it very much like the sun actually would. It also has an Earth in the sky that does the same. This video is the first one to really make some important points clearly about why the colony is the way it is, and what it would really be like to be there.

I found it challenging keeping the video down to a reasonable time while covering all the main points. The live fly-through conversational approach did help keep it engaging. I have already received helpful feedback that will inform updates to the colony. I got the dynamics of the human centrifuge wrong and based on that information will be tilting the outer wall of it to be horizontal to the direction of artificial gravity when the centrifuge is at full speed. Moving naturally wouldn't be as difficult as I claim in the video. There would be a gradient to the strength of centrifugal force between your head and your feet, and it would take training to move very much while on it without getting dizzy and nauseous. The one shown would rotate at about 8.5 rpm. Basically, I'm adopting the optimism of Al Globus that people can be trained to function in that environment with no symptoms, as explained in this paper by him and Theodore Hall. In later habitats, there will be space for centrifuges with longer arms to reduce these issues. It may be that exercise on them will need to be limited, and time on them is instead best used doing sedentary activities. It is an area where we know very little indeed. The centrifuges are probably needed though, so they stay.

I also had a long conversation in our chat room on space.stackexchange about solid waste. My Russian friend with the biophysics degree convinced me it should all be incinerated in a separate structure, and the gases and residues collected and stored. Ashes and charcoal get incorporated into soil production, carbon dioxide is released into the hab at whatever rate the plants can take it up, any excess carbon dioxide is used in any one of a range of useful chemical reactions to produce important products for the colony. Making those models will follow after several others that are higher priority, but they are now on the to do list.

I can talk about this stuff forever, and will if you don't stop me, so any other feedback is very welcome.

Advancing Colonies

noreply@blogger.com (Kim Holder) — Thu, 15 Feb 2018 16:03:00 +0000

(The posting of this on Blogger was accidentally omitted when this blog was written, about 5 weeks ago... Oops.)

Much work has been done in the last 2 months or so on revamping the structures of Cernan's Promise. Much more than is shown below, actually. As is common, much of my time is spent staring at my monitor, trying to figure out what makes sense on the Moon. This is punctuated by research online, consultations, and occasional deletion of current work to start over. Maybe a third of my time is actually spent building digital models.

To give a sense of the new directions, here are a few images of the Atrium habitat, the first to be occupied at the Lalande Crater colony of Cernan's Promise, which is the second colony constructed, after Inukshuk at the north pole. This is an evolution of the previous version. I rebuilt the entire thing fresh. Even with all the thinking, it still went ten times faster than the last build. May this be a sign of things to come, for it is necessary to move beyond this phase soon, and seek to make this a business. It will all be open-source, and the colonies will always be free. But, to do this will take a considerable amount of labor. It needs revenue.

For now though, i present for your consideration the beginnings. I spent only a day on giving things color, lighting them, and adding a little bit of imagery. With time, these images will look highly realistic.

The first image is of the top window at the south end of the Atrium hab. The glass is 6.5 m across (21 ft) and 10 cm thick (4 in). It maybe doesn't need to be so thick. The windows on the ISS cupola are 7 cm thick because of the amount of debris in orbit. In this case, a consideration is the backscattered spray of particles from collisions of cosmic rays with the ground. Those particles won't have the energy to penetrate too far, but we don't know how far or how many such particles fly around above the Moon's surface. It's really hard to say whether this thickness of glass is a sensible measure for long-term residents, or it's too much, or too little. This is a great example of the sorts of things i fret over - a barely visible detail that nevertheless has a lot of implications for the overall design, as glass is heavy and has to be locally produced in order to build a large colony.

Finally, a window on the Moon i can get behind.

The reason this window can see the Earth is it looks onto a shaft lined with mirrors, with the south face of the shaft tilted 45 degrees so it reflects whatever is directly above it into the hab. As this colony is on the equator, and the Moon is tidally locked to the Earth with an orbit inclined only 5 degrees to it, the Earth hangs in the sky near the zenith all the time on the Moon's equator. It should always be in view looking out this window. Okay, it won't actually look that big, that was a bit of license. But it will be 16 times the area of the Moon from our perspective, and 50 times as bright. In fact it might be worth hanging a big lens above the window that magnifies it so it actually does appear this size.

So let's talk stairs. On the Moon, climbing a step as high as steps on Earth would take the effort needed to climb a step an inch high in Earth gravity. It just isn't enough to feel like any kind of exercise at all. I think i'd actually find it annoying after a while. The stairs in the habs are all between 40 and 50 cm high (16 to 20 inches). That requires effort comparable to stairs here at home. But if that was the only difference, there would be two problems. One, that doesn't take into consideration that inertia is the same everywhere. Two, it is absolutely no fun. These problems are actually important to consider together. On the Moon, i think people are going to want to make use of their superhuman capacity to leap great distances a lot. If you are trying to run up oversized Earth-style stairs though, the challenge will be to not fall flat on your face because your forward inertia has not diminished, unlike the pull of gravity. It could be so challenging that one would be obliged to take one's time or risk a nasty spill. No fun at all.

Low gravity stairs require a lot of thought.

Thus, i made these stairs in which one hops from side to side to step up or down, and if desired, the pole can be used to aid in balance. Or you could slide down the pole. Or shimmy up it, for that matter - it wouldn't be very hard. As the path one takes is vertical, there is no need to think about inertia. With a little practice, i bet it would be easy to slip up and down these stairs, including jumping multiple steps, hauling yourself up after you've climbed part way, swinging off them from part way down, and generally getting good fun exercise out of them that fits neatly into your day. And yet, if you are carrying a tray of food, for instance, or you have a sprained ankle, or what have you, you can also use them gingerly and still get where you are going.

That's the kitchen in the corner there. I'll leave that for now though.

The full 35 m height of the hab, showing the planters suspended from the beams, all the levels, and a bit of the crew quarters at left.

On the left here is a row of crew quarters. This is the first hab on this site, so the quarters are built in a standard modular fashion to save space and time. (This is in contrast to the typical method of building quarters in the colonies, where each couple builds there own however they want, within the large open spaces of the habs.) The hanging planters of the gardens are above the rows of quarters. A fair bit of light still filters through them during the day, providing a soft green lighting like a forest in the area below. The catwalks along the planters for tending the plants will be mesh to minimize reduction of light - i haven't made those yet.

Here you get a sense of how high the hab is. Tall structures are a very good thing on the Moon - or rather, deep structures. They are built in excavated pits. Depth automatically provides good radiation protection and assists with thermal control, especially if the bottom of the habs are in contact mostly with rock instead of regolith. And in lunar gravity it makes sense to organize things much more in 3 dimensions. Reaching something 2 or 3 meters above your head is really no challenge, moving between floors takes very little effort. This allows highly efficient use of space, while providing a sense of openness. This atrium is 35 m high, with 10 levels. The internal structures are mostly suspended from the beams of the roof rather than being supported from below - light and efficient.

Up close to the beams, a view of the sky. All the hab can see slivers of sky through the beams, and get natural sun from there.

Between the beams is a view of the sky through glass. The beams are 50 cm wide and there are gaps of 75 cm between them. This is the radiation blind design discussed [here](https://www.moonwards.com/colonies.html#AtriumRadBlind), in which there is a dose of radiation coming from directly above, but to the sides it is blocked, and overall the reduction in radiation is something well over 90%. This is a first stab at representing what that would be like. The light is completely wrong, as is the sky, obviously. Mostly this gets across how much of the sky would be visible. The beams are very tall, to fulfill their radiation-blocking role. They shouldn't be black, i don't know why the cream color of them renders as black. Lighting and transparent materials are a complicated thing in 3d software. I'm still learning the basics.

The mouth of the tunnel portion of the hab, the surrounding levels, and the 28 m tall gym in the corner

This shows more of the layout of the levels, the mouth of the large additional section of the hab that is a tunnel, and the gym area in the corner. The curved bottom of the oval tunnel, under the main floor, is an area for all the equipment needed to maintain life support and hab systems. The interior of the gym is 30 m tall.

Looking down from the top platform of the gym. The ropes, ledges, and rope net for climbing and parkour are shown, and the two trampolines at the bottom.

This is a view looking down from the platform along the wall at the top of the gym. Jumping from this platform would be a drop of 28 m. And it is intended that people would often to exactly that. Everything is padded so that such a jump is perfectly safe, even if you landed badly. It is equivalent to jumping 4.7 m on Earth. If you hit one of the trampolines shown in light green, you could bounce right back up to the height of the platform. The trip in each direction would last about 6 seconds. Every surface is designed to be climbed on and jumped between. With no need to fear falling, this space is full of possibilities. As it is hard to work up a sweat without there being a big vertical element in your exercise (or else dealing with the awkward matter of inertia vs gravity), lots of vertical space is a good design for a lunar gym.

Infrastructure stuff - the tanks for the water supply, thermal control, the walk-in fridge and freezer, exterior view of the reflecting window, and structural elements of the atrium.

There is lots of infrastructure behind the visible things in the hab. This needs lots of work still. The habs make use of a large water supply (thanks to ice mining at the pole) to ease the burden of thermal control. That is what is in the biggest tank. The rest i'll explain later. There is a lot of thinking behind it but it is pretty dry.

Dry composting toilets on the Moon... these too required a lot of thought...

Ah toilets... these things took me a week. They are closely based on dry composting toilets on Earth, as all of the residents, um, output is valuable stuff that must be recycled. But it can't smell, and the volume of air in the hab is small enough for that to be a challenge. So the toilets look fairly ordinary above ground, but under the floor are a mass of tanks and tubing and filters. And they feed into larger tanks, and the drums behind them are emptied into a large main composter in such a way as to minimize odor. These things could be a blog post by themselves. But, let's leave that for now...

So this is what i've been doing, in part. Lots more work lies ahead. Videos and new 3d models that can be manipulated should get posted much more often beyond this point.

Great Big Timeline

noreply@blogger.com (Kim Holder) — Mon, 06 Nov 2017 21:08:00 +0000

Our new timeline maps out a vast set of complex, interconnecting plans leading to a solar system with major colonies on four worlds. When the timeline ends, there are thousands of ships trading megatons of goods from Mercury to Titan. It costs about as much to go to the Moon as it costs to fly half-way around the world today. Cities are being built at a high clip across the face of the Moon by robot crews that are only lightly overseen by a small number of people. We’ve launched small probes to other stars. There are satellites around every significant celestial body in the solar system, and rovers on all such bodies with a solid surface. Political and economic power has shifted dramatically into space. Our sense of who we are has changed forever.

It’s that last point that is the reason i work on Moonwards. I have this deep-seated feeling that we are in a time when our technical powers are exploding in scope so profoundly, we are about to be forced to redefine who we are. Already there are a whole set of arguments about what we should and shouldn’t do. We’ve been stepping into the pages of science fiction for some time, and that’s now accelerating, quickly. People need to process that, and think about all the implications.

That is why Moonwards throws off the shackles of political reality and shows what we genuinely are perfectly capable of doing if we tried. I think it’s important to make clear just how much we are holding ourselves back by clinging to petty differences and fretting about consequences. Here is the difference it makes: linear growth, or exponential growth.

For people to appreciate the difference, the place that shows it has to be realistic, detailed, complete, and open. This is what Moonwards is meant to become. It has to do it well enough that millions of people spend enough time there that it makes them start thinking long and hard about what really matters in life, and what they want for themselves and their children. It is critical for people to understand that the Moonwards logo shows cities glittering across the Moon because that could be only a century away. That isn’t a wild fantasy. That is the level of responsibility we need to shoulder. If we don’t, we are not only turning away from incredible growth that improves everyone’s lives and averts untold suffering, we are inviting new disasters on a scale we’ve never undergone before. The worst thing the world can do with power is ignore it. When we ignore power, we hand it to those who don’t care what anyone thinks.

Since this is how i feel about it, i reworked the timeline until it got across the true scope of the issue. Now i need to incorporate the new timeline’s changes to the colonies and ships into the text of the rest of the website. Then i need to sketch all the models needed to document it. Their first drafts really need to be simple sketches, so i can get through all of them in a timely manner. This is all meant to be a framework that other people flesh out and improve, so now that it has a solid foundation i’m confident in, it is time to stop fiddling with details. I am glad i did that, because to lead on this i really need to appreciate all that’s involved enough to work with all the people it needs. Those people need a whole landscape laid out so they understand how everything fits together and they can see where we’re headed. That landscape shouldn’t be any more detailed than that though. It should maximize the room there is for them to exercise their talent. There’s going to be plenty. Oodles. So much it’s going to be a major challenge looking after it all. It’s going to be years still before i can slow down my learning process or put in fewer hours.

I’d really appreciate input on the timeline. It’s about 80 pages of text, but i’ve split it up into chunks as best i can to make it digestible and easy to navigate. It needs images and diagrams, but right now i need to move on, i’ll go back and look after that later. I’m now quite confident that the major pieces of technology it’s built around are the best ones, in the paradigm the project assumes, of great technical decision-making and deep financial commitment. However i’m always eager for technical input. If you think anything is wrong, or missing, or misguided, please say so. And please bear in mind that although i haven’t been able to reward any of the people who have helped me so far, i am very aware of how much help i’ve received and intend to reward those people when i can.

In fact i’ll be seeking technical review of the architecture from a few people once i have the sketched models to clarify what i mean. And at that stage, there are several other new things that come into play. I spend a good chunk of my time now thinking over how to pursue alliances and finances so the virtual colonies can be properly built and go live with the right format and platforms. There are a number of steps that need to be taken in the next six months or so that must be handled with great care.

The Moonwards timeline shows off a big future worth struggling to reach. When the virtual colonies open, they will dazzle visitors with big ideas and present a clear and feasible path to get there. Then we’ll fill it all in together. We’re going to make something so stunning it changes the world.

The Mother Ship

noreply@blogger.com (Kim Holder) — Fri, 25 Aug 2017 22:09:00 +0000

True space settlement depends on being able to have children out there, including pregnancy, childbirth, and the whole process of raising a happy, healthy child. We know very, very little about what it takes to do this in the harsh environment of space. What we do know suggests that the radiation protection and gravity required is far higher than for an adult. As a mental exercise, let us tackle a chunk of this question. Here follows a sketch of the mother ship - a ship compliant with conservative estimates of the protection needed to safely transport an expectant mother from the Moon to Earth.

First, the setting. There is a point on our timeline, after a pretty large, bustling colony has been set up at Lalande Crater on the Moon's equator, where a small number of young couples intending to have children are accepted into the colony's population. This step is taken after extensive research into pregnancy in higher mammals has been done. For now, let's posit that shows that very early pregnancy is alright in lunar gravity, but normal fetal development requires something close to normal gravity after that. Also, that only a very low level of cosmic radiation is permissible. This gives us a starting point for really thinking about the whole thing, which is what Moonwards is for.

Now, the very limited data there is on mammalian embryos in microgravity mostly show abnormal development. There is no information at all in low gravity like the Moon. A good review of current data is in Effects of Microgravity on Cell Cytoskeleton and Embryogenesis, by Susan J. Crawford-Young. Maybe a little gravity really helps, maybe the fact that experiments so far haven't controlled for other factors like elevated radiation and launch stresses means they've over-emphasized microgravity, maybe periodic exposure to higher gravity or other measures can offset problems... What can i say, you have to start somewhere. I have no good response to the low-gravity factor, in particular during the period before pregnancy is even detected. A woman known to be pregnant could be placed in higher simulated gravity for transport, except for a couple of short gaps. Before anyone knows she's pregnant, if a regular Moon lifestyle isn't enough, we're sort of stuck. It would be time to talk about orbital colonies for pregnancy. And i've even started thinking more about that... But first, the mother ship way, which addresses radiation.

The mother ship blocks cosmic rays well enough for a pregnant woman to be safe. She would be safe in the colony itself - it's been designed to have plenty of protection, even more so at this stage in its development. It would be like being on Earth in that respect. She would also be safe in the space station that anchors the equatorial tether complex. It is huge by the time these events are in play, with plenty of shielding. Same goes for the ship that ferries her from that station to the corresponding station on the other end, in Earth orbit. That ship shuttles between the Moon and Earth by being tossed between the upper tethers of each, it only needs enough engines and fuel for course corrections. (And i'm going to go ahead and start referring to them as toss ships, because it makes it a lot easier to explain things, and what the hell.) So it too is a big thing, designed to carry very heavy loads. And the Earth space station? That one gets started with an actual metal asteroid of worthy size, it's super shielded. We're talking about a time when there is major commerce in cislunar space and projects like this happen, thus the whole motivation to finally resolve this space-family thing. In all of these locations, our mother-to-be has space to stretch and move, decent medical facilities, and access to a full gravity environment in centrifuges. The full mother ship need only get her safely from the Moon's surface to the station in orbit, and the mother ship capsule provides shielding during other parts of the journey.

So, what level of shielding is needed to be pretty sure the embryo within her is safe? To answer that, let's talk about cosmic radiation, and embryonic development.

The data on exposure in the womb to the type of radiation we are talking about is limited to that resulting from the bombing of Hiroshima and Nagasaki - and it still isn't really the same. Below exposures of about 0.4 Gy (which means 0.4 J/kg of radiation) the clinical effects were limited to increased risk of cancer later in life. There was risk of mental retardation above 0.4 Gy, but we aren't contemplating anything close to that. Contrary to popular belief, there was no increased risk of stillbirths or birth defects among children exposed in utero to the a-bombs. Other than these case studies, the only data on exposure of embryos to ionizing radiation is from animal studies. I have found no such study that used radiation more energetic than gamma rays, which is so different there is no point talking about it.

The kind of damage that is done by cosmic radiation, especially high energy nuclei (HZEs), is in a different category. I really like this image from NASA's Space Radiation Cancer Risk Projections and Uncertainties, on page 5, as a way of getting it:

A comparison of particle tracks of different ions, from protons to iron, in nuclear emuisions, clearly showing the increased ionization density along the track by increasing the charge Z. The left panel shows three nuclei of human fibroblasts exposed to gamma rays and Si- or Fe-ions, and immunostained for detection of gamma-H2AX. Each green focus correspondsd to a DNA double-strand break (DSB). Whereas the H2AX foci in the cell that is exposed to sparsely ionizing gamma rays are uniformly distributed in the nucleus, the cells that are exposed to HZE particles present DNA damage along tracks (one Si- and three Fe-particles, respectively), and the spacing between DNA DSB is reduced at very high linear energy transfer.

And here are two quotes from the lead author of this model, Frank Cucinotta, from his interview on The Space Show on Aug 1 (quoted with permission from TSS). The first is at 17:17 of the show:

When you look at an x-ray, and you look at an important molecule like DNA... it only can ionize a few times with that volume of say 10 nanometers, but a heavy ion can ionize thousands of times in that same 10 nanometer volume. So it's a true qualitative difference. That's what we're worried about.

The second is from 25:52:

There is different kinds of damage to DNA called strand breaks, and you get single strand breaks all the time... your body knows how to handle that, and then there's a little bit more complicated, a double strand break meaning that you've broken both strands of the DNA within a short distance, say 10 base-pairs from each other, that also occurs somewhat in metabolism. But there is something else called a complex break, where you have double strand breaks, single strand breaks, and base damage all very close to each other and this is what ionizing radiation, this thing it can do, your metabolism won't do this. And from those events you have mis-repair that leads to mutations and chromosome aberrations.

Alright. So, we don't have any data, but that kind of damage sounds so awful, you'd figure that expecting parents would insist there be none of that. That's just off the table. Chromosome aberrations in an embryo that is dividing its little cells as fast as it can has got to be a really bad thing.

Therefore the mother ship will surround the mother-to-be on all sides with 3 m of water. That is equivalent to the atmosphere above you when you are in a jetliner at cruising altitude. Pregnant women can safely fly, so our hypothetical mom-to-be would be fine in this environment even for a day or two.

If we provide a capsule 2 m in diameter and 2.5 m long, surrounding that with 3 m of water amounts to 386 tons of the stuff. Add mass for the structure and systems, and let's call that 450 metric tons. Our shuttles use nuclear thermal rocket engines, ones that are a little fancier than usual because they have a system to inject oxygen into the nozzle, which combusts with the super-hot hydrogen exhaust and boosts thrust during launch and landing. This is known as a LANTR design. Water is, as it happens, also good shielding against neutron radiation from nuclear engines, so we can save some mass on shielding for the shuttle that is the designated mother ship.

With 4 engines and the fuel needed to get this ship to the foot platform of the equatorial tether, this ship masses 480 tons. The whole section composing the capsule, its shielding, and all its systems then separates from the ship, and is placed on the climber car to be taken to Gagarin Station, 5000 km above the surface. 450 metric tons would be the maximum payload that tether is designed for. Supposing the best material we have for making tether cables in that day is still Zylon, the mass of the whole cable up to the station would still be only 4000 tons, including safety margin and extra infrastructure like counterweights, the foot platform, and some maintenance stuff. For comparison, the main cables of the Golden Gate bridge each mass 11,000 tons.

If the climber car can manage an average speed of 1000 km/h, she gets to the station in 5 hours. There, she can stretch, and shower, and eat, maybe check in with a doctor, and get a good night's sleep all in a proper full gravity environment, in the O'Neill cylinder that extends from one side of Gagarin, across from the shipyard. Her capsule is moved around and docked to one of ferries that go up to the toss ships at the Earth departure platform part way up the upper tether. The next day she goes aboard her capsule again, and the ferry takes it up to the toss ship and loads it into its cargo bay. That trip takes another 5 hours or so. Then she can get out and go to the toss ship's centrifuge section for the 3 day trip to rendezvous with the upper tether of the Earth tether complex, Anshar Station.

Anshar Station is a whole different beast. It's still rather new when the first returning woman with-child comes aboard, and it can pamper her with a fancy centrifuge torus nestled under its metallic bulk, overlooking the Earth below. If we don't have enough experience by then to capture an asteroid with a suitably tempting metal content, and confidently maneuver it into orbit around Earth, we aren't really trying. To properly enjoy our new space station, built around this mine in the sky, we should drain the inner Van Allen belt with the scheme proposed by Robert Forward. Orbiting at an altitude of 3500 km, with an upper tether that reaches to 6500 km, that cable is hefty enough to safely dock cycler ships from Mars and Venus. If it was Zylon, it would be well over a megaton, so it would really be better if we had carbon nanotube cables by then. They don't have to be perfect nanotubes - not even close. Just good ones, manufactured in bulk. The lower cable would really benefit from that too, though it could be done with a few hundred kilotons of Zylon. Anshar is built to be Grand Central. It's foot moves at just 3.8 km/s relative to the Earth's surface and it can move a couple of kilotons along the lower cable at a time. But we can discuss these things another time...

The point is, our mom-to-be can be ferried down the lower cable still in her protective mother-ship capsule. She is then just 250 km from the cradle of humanity. The mother ship capsule is way too heavy to be used for re-entry into the Earth's atmosphere. Even if you could brake its descent for a soft landing, the cost of relaunching it for return to the Moon would be too high. Despite the tether foot platform reducing the speed a rocket needs to reach by half, it probably wouldn't make sense to have reusable rockets or space planes with payload capacities over 200 metric tons at most. The mother ship capsule goes back to the Moon for the next mom.

Anything dropped from the tether foot is immediately on a steep re-entry trajectory. I have asked about what sort of heating a reentry capsule would go through in that case. Being able to just drop things from the tether and have them safely reach the ground would be very advantageous, but we have to assume it won't be a good idea for our expectant mother.

She could descend in a space-plane sort of vehicle, that uses lift for a gentler re-entry. The process would take longer but be smoother, the heat of reentry is dispersed over a much larger area and mass, with much lower g-forces, and the plane can go straight to a landing strip instead of probably landing on water and being collected. The space shuttle took about a half hour to re-enter, so we could maybe reasonably suppose a space plane starting with half the forward speed could do the same sort of trajectory and accommodate twice the payload. Thus, if we wanted to, we could tuck our future mom in 50 tons of shielding for that trip, almost all of it on the skyward side, and protect her pretty well during that brief time. She lands at a convenient space port and is greeted as the first woman bearing a lunar child.

Okay, so this is a distant future. But this is doable. This is a matter of how bad we want it, which is really what the whole matter of space exploration comes down to. The question now is if the spaces of a few hours when she is in low gravity or microgravity during her trip are safe, and if conception and the days before pregnancy is detected can happen in low gravity. If so, this is something that would work. The mother ship capsule is pretty expensive, but highly reusable. The real expense is in the energy required to move around that great big thing. We now have a model for this we can start with. In due course, it will all be placed in Moonwards' virtual colonies.

Thinking About Thinking About Space

noreply@blogger.com (Kim Holder) — Fri, 18 Aug 2017 17:19:00 +0000

The Starship Congress last week was full of expansive ideas of brave new worlds and the odysseys to reach them. I have a new theory that if you pack enough space geeks close enough together they will start to spontaneously levitate. I'm in the thick of this community, but i gotta say - wow, we really need to get more grounded.

There is something super-seductive about creating a vision for a whole new place completely outside our current reality. Yep. Don't i know it. If you work on one hard enough it develops a certain tangibility in your head and it is hard to listen to criticisms of it. Yep. Been there. On the other hand...

The space nerd community is small and so we can't achieve anything unless we pool our resources. Moonwards is, of course, about stitching together the best of our ideas into a whole virtual world spanning all of cis-lunar space and hopefully then beyond it. Watching the presentations at the SC last week caused me to wonder how akin that task is going to be to herding cats. I have had to pick an initial set of ideas in order to create a solid foundation that other work can build on. In the next few weeks i am going to discover exactly how easy or hard it is to splice other visions onto it in a way the creator is okay with. This will get interesting...

So let me get back to work at creating the medium that can allow it all to grow and knit together into something greater than its parts. All we need is the right space. Get that going and it'll grow like crazy-ass mushrooms.

Reworked Power Plant

noreply@blogger.com (Kim Holder) — Mon, 19 Jun 2017 20:16:00 +0000

Six weeks ago i posted about a new draft of the solar thermal power plant designed for Cernan's Promise. Oh how it has changed since then. The process of improving that model has been an important test case of how to elicit input on a design, and work through improving it, with online collaborators. Once again, it was done mostly by consultation in our chat room on space.stackexchange. The conversation there goes on for pages and pages, supplemented by sketches and links.

A typical solar thermal power plant for use on the Moon. With all the usual parts we know so well.

We thought this through as well as we could with the tools we have available. MolbOrg was a big help during this phase. Sigvart framed several of the initial requirements of the plant when we started it a few months ago. Very roughly what you are looking at would turn sunlight into a megawatt of electricity that would be constant day and night. Constant power day and night, from a power plant that can be built almost entirely on-site using local materials (by this stage in the colony's development) is key technology. Nuclear reactors get the equatorial colony to this point. The initial base at the pole can simply use solar panels, and the presence of that base supports this development. That big complicated thing in the image above is something you have to be able to build if you want to actually live on the Moon in decent comfort. Fortunately, while it is quite large, it isn't very complicated. The first one will be a challenge to get working. After that, they are modular pieces, none of the parts are hard to fabricate, the materials needed are plentiful, and refining them is relatively straight-forward.

A parabolic mirror unit showing the pipe it rotates around and all the support structure.

Above is one of the parabolic mirror units. The mirror is 40 meters wide across the curved part and 20 meters long. It can be made in sections that get assembled, of polished aluminum with a honeycomb backing for stiffness. If possible, a vapor-deposited layer of aluminum on a quartz substrate would be even better. This mirror has to focus all the sunlight that falls on it onto the very narrow iron pipe that runs along its focal point. That pipe is only 8 cm in diameter. (It is barely visible as a thin blue line running between the support towers, surrounded on its outward side by a half-tube radiant barrier of reflective foil layers.) A precisely shaped mirror that won't deform after a few day/night thermal cycles is important. Quartz barely changes size at all with changes in temperature, so it would be helpful.

The axis of the mirrors runs north-south and they turn 180° from dawn to dusk. Thanks to the fact the Moon has only a very slight tilt toward the sun and this colony is on the equator, with only slight adjustment the mirror stays focused on the pipe year-round. Depending on how quickly the heat carrier fluid runs through the pipe, how big the heat storage tank is, and how quickly the generators are pumping heat back out, the temperature of that pipe at the focal point can be adjusted. For the moment it has been set as operating at 1156 K. That is the boiling point of sodium, which is being used as the heat carrier. When the sodium returns to the huge heat storage tank and dumps its heat there, it liquifies again.

A counterweight is used to place the center of mass of the whole rotating part along the focal point of the mirrors. This way, it is easy to turn the mirrors, and the pipes can remain stationary.

The pipe configuration needs to distribute heat in the best way for overnight functioning of the generators.

This tangle of pipes is the taxing part of this scheme. The yellow ones are coming in from the mirrors (of which there are eight in this particular model). They are shown connecting to large pumps right now. We had also considered using liquid aluminum as a heat carrier, in which case there would be no phase change and it would have to be pumped at a rate of about 750 kg a second through each pipe. Hopefully now they can all be eliminated - but in case they can't they are still there. (These models are ongoing works in progress, continually improved, so situations like this crop up regularly.) Then all the fluid mixes in the light blue donut shape and exchanges heat with the gray pipes that loop down through each section of the red tank. The red pipes coming in from the bottom come from the hot end of the Stirling engines generating electricity from all of this. They carry nitrogen gas to the large set of orange pipes that spiral around the red tank. During the day, the gas flows first to the inner edge of those spirals, such that when it is coldest, it is flowing around the walls of the red tank. Then the gas spirals outwards, running around that tank several times before returning to the Stirling engines. When night falls, the flow is reversed (which will involve a bit of pumping) and the gas starts at the outer edge of the orange spirals and moves inwards towards the tank before returning. There are many levels of these orange spirals which all flow into the large red pipes, in this way the entire height of the red tank has pipes spaced 50 cm apart running around its walls, carrying the nitrogen working fluid.

Manufacturing and maintaining so many pipes isn't easy, but a couple of things help. First, the orange pipes run through solid cast stone, so really they are voids in the stone, not pipes per se. Casting that stone is a lot of work but also simple work that uses almost entirely focused sunlight to do the job, so that can go pretty fast. Second, all the other pipes can be iron (though it might be nice if the bits actually getting hit with the intense sun were quartz, maybe). Iron is by far the easiest metal to refine on the Moon. Also, with some digging around, remnants of meteors might be found in the central mountains of some craters, and if the asteroid was metal there might be pure iron deposits. And even better, asteroid mining is part of this whole plan anyhow, and a metal asteroid brought into orbit would have plenty of pure, elemental iron.

The dark grey is solid stone, except for the orange pipes from the last image. The light grey area is powder regolith insulation.

Here are our nested tanks. The red one is filled with regolith selected for low calcium content and enriched as much as possible with sodium and potassium. That causes its melting point to lower. Basalt lava goes through a very complex crystallization process when it freezes, the end result being that it slowly thickens as it cools, crystallizing and recrystallizing in stages until it is finally solid. By concentrating as much of the freezing process as possible in the low end of the temperature range in which it freezes, the heat released by the freezing process can be used to help the generators continue to produce just as much power through the long cold night as they do during the day.

The dark grey one is the stone with the spirals in it. The spirals are there so that the stone is a supplemental heat store that regulates how heat drains from the system to optimize heat flow. By spiralling outwards during the day, heat is shifted from the red tank to the stone before continuing on to the Stirling engines. (The stone is made of minerals with high melting points that are easily purified out of the regolith, and could be mostly acquired from the slag of other processes. It can easily take the heat.) By spiralling inwards during the night, the heat of the stone is taken first from its outer perimeter. Only once the outer perimeter has cooled is the heat taken more from regions closer to the red tank. Balance the geometry and mass correctly, and the desired temperature can be maintained through the night.

The light grey material is loose powder regolith. By filling an outer tank with that in a nice thick layer, the amount of heat that reaches the very outer skin of the whole thing is minimized.

The radiator units rotate so that the sun doesn't fall on the panels. The insulation underneath them protects them from the heat from the ground.

This image shows the radiator units that cool the cold end of the Stirling engines. (I'm not going to really talk about the Stirling engines much. Large Stirling engines like this can be pretty efficient, and the parts are relatively simple shapes much easier to fabricate on the Moon than, for instance, turbine blades. That's why they were chosen, if you'd like to know more about them googling them brings up tons of stuff.) The radiators are the black and brown panels in the middle of the grey boat shapes. They turn through the day to keep the radiating surfaces parallel to the rays of the sun, so that almost no sun touches their surfaces. The boat-like things are made of foil layers that stop the heat reflecting off the ground from touching the radiators either, while reflecting the heat coming off them into the sky. The pipes that go from the cold end of each generator, to a heat exchanger tank, and then to each radiator unit, are visible mostly at the bottom. Each radiator also has a heat exchanger underneath. The radiators work by using heat pipes. When i make up the SketchFab version of this i'll talk a bit more about that.

These things are all pretty large. The red tank is 14 m across, the stone around it is 24 m across. The radiator panels are 21 m wide and the boats 44 m long. A number of small details have also been modeled but are too small to see. The radiator panels have a corrugated surface and many individual heat pipes weave through them. All the pipes have been sized and run where they need to go, as their overall length is a relevant number.

Plenty to reflect upon

Another thing there is a lot of, is reflective surfaces. The mirrors reflect with aluminum, for everything else, silver is used. Only just enough to reflect well is needed, and actually on some surfaces there is no reason it needs to be glossy - not on the tank or the stuff around the pipes, or on the outside of the radiant barrier boats. (I'll fix that, for now the use of the traditional coppery tone of radiant barrier foil on satellites and such is at least pretty.)

So, a large fraction of this construction is pipes, and reflective surfaces. Really simple stuff. All the structural components are pretty simple too. The minerals that go into the lava tank and the stone around it need to be processed, but not very much. Many parts of the Stirling engines, the pumps, and the radiator panels could be 3d printed by sintering metal powders, or cast. Casting or blowing of glass for other things would also be useful, especially if the glass was made of fused quartz.

If we are right about what you see here, there are ways to make big things on the Moon using local materials and simple processes. After the solar panels and the nuclear reactors of the early days, this is the sort of thing that has to happen if we are going to live on the Moon. This is the kind of scale and methodology we need to think through.

We can't discuss our long-range future without mapping out things like this. Without it, there is no way to get across the sheer scale and scope of endeavors that will happen in just a few decades, one way or another. If the public doesn't appreciate how vast the changes are that are afoot, we will go into this blind. We have the tools now to work together, and move forward with our eyes open. For the first time in history we have what it takes to collaborate in huge numbers across the whole world. What you are looking at is an attempt to spark that. The opportunity is huge. The future will be forged by whoever executes plans with this kind of vision. The greater the number of people involved in that, the better for all of us.

Flee-osophy

noreply@blogger.com (Kim Holder) — Wed, 24 May 2017 17:36:00 +0000

There is a strong tinge of escapism among space fans. That isn’t necessarily a bad thing, escapism gets a bad wrap. It just has to be used with care. I think it’s good for people to remember that things could be way, way better than they are. A vision of something that would be wonderful but can only be achieved with great effort can actually bring people together and focus them on making that effort. The problems begin with the false promises and hand-waving. If your head is out there, but your heart isn’t rooted down here, you’re in for trouble.

When i look around at the epic space projects proselytized by most of the prominent space advocates out there - settlement of Mars, supply of the world’s power from space, salvation of humanity, riches beyond compare - i’m disheartened. And please bear in mind that i believe in these things. I just think they have the order of operations all wrong. They skip over the heart and soul of the case to be made here. Many of them neglect it so badly they advocate sending people into danger, as though a bright future is secure as long as we manage to get out there and build giant things at whatever cost.

Au contraire. The brightness of our future is directly proportional to how good we are to each other, and little else is relevant. We are entirely capable of solving all the world’s problems with capabilities we already have, but we don’t because we are so messed up. Sending people into danger to do something that could be done better and cheaper right here on Earth if only we would grow up i’d call a net loss for our collective maturity. Now, i’ll grant you that although the kind of investment needed to create solar power production in space for the whole world is definitely far more than the investment needed to create solar power installations on Earth that could do the same (even including the cost of power storage and transmission infrastructure), contemplating that venture in space is tempting because it sidesteps all the politics that bog down the real world. It is the one arena where it is almost believable that one nation, or even one company, could slip the bonds of Earth, go it alone, and achieve something so singular that it changes all our lives forever. But the devil is in the details. Don’t flee that devil. He is trying to show us the lesson we really need.

The important thing here is not milestones. To hell with milestones. The inspirational thing about Apollo was not the small step for a man, it was the giant leap for mankind. The Apollo astronauts knew it better than anyone. They weren’t there because they were great heroes, their mundane workdays on the Moon were not the source of inspiration. They were there because literally hundreds of thousands of people working closely together, and exerted themselves to the utmost mentally, to plan and build the most astonishingly complex machines we had ever made. Our ability to work together in that way was the magical thing. That took us to a magical place. It wouldn’t have been magical if we hadn’t overcome our own limitations to get there. That’s why people mostly don’t even look out airplane windows anymore. The Earth stretched out below means nothing to them anymore. Achieving flight hasn’t freed us from our suffering. It has only made it a bit more complex.

That’s why Apollo can’t be repeated. It’s when you overcome yourself that you are taken to a place of magic. It’s not necessary to reach a new place to experience that. It is necessary to see the place you are for what it is - endlessly complex and interconnected with everything else.

To have that experience, take your time, share everything, listen well, and speak with care and honesty. What we space nerds have to give the world is our sense of the great abilities and experiences that lie in our future if we work hard together. That should be enough. Be content, and don’t get distracted with trying to make it happen. Just try to get across what it would mean. After all, that’s why it matters to you. Just pass that on.

Drafting Ideas

noreply@blogger.com (Kim Holder) — Sat, 06 May 2017 17:14:00 +0000

We were chatting over the last week about the thermal energy storage system we have drafted right now for the colony, which is a bit like some solar thermal power plants here on Earth. (I always sort of enjoy it when i have a legitimate reason to specify that i'm referring to something 'on Earth'.) Our [chat room](https://chat.stackexchange.com/rooms/37071/moonwards) has been rather productive in the last while, this discussion was such a case. To encourage that, i made a new cutaway sketch of the heat reservoir and connected systems in order for us to better visualize the concepts discussed and improve the design. As usual, it is a design for an advanced colony, and so it is rather audacious by current standards. Once we are there and thriving, something like it will make sense on the Moon.

A jumble of pipes and a huge amount of lava - it's the future!

The model is here on our SketchFab page. This system is discussed in the section on solar thermal turbines on the website. We started talking about the heat storage mass. Right now the hot pipes from the mirrors dive straight into the ground and the deep pond of lava created around them simply has to be big enough that even as heat drains from it all through the long night, it is still hot enough to heat the gas that drives the turbines. Powder regolith insulates very well, so that actually isn't as crazy as it may sound. However, it does mean that a lot of the mirrors in the system are simply there to make the heat store big enough to last through the night. Mirrors are simple to make, so why not just make those extra ones instead of making an actual tank to hold a huge amount of lava? Well, the pipes full of molten salt that carry that heat back to the reservoir are not simple to make and will need repair more often, and the longer they are, the less efficient they are. Besides, once you have made the tank, the performance of the whole system goes up, and stays up. Such a tank will last a very long time with little upkeep.

The joy of engineering on the Moon is the low gravity and the hard vacuum, when you can make it work for you. In this case, it works for you like busy bees. The reason powder regolith insulates so well is because even when it is packed hard it is half empty space - truly empty, vacuum, which means no heat conduction or convection. So, since the same material on the Moon can support six times as much mass as it can on Earth, the best way to make a gigantic tank out of local materials, that is capable of containing a vast amount of lava, is to pack powder regolith around the lava in a very thick layer and make sure it doesn't melt. Then the heat that reaches the outer skin of the tank is low enough to make the tank out of poured stone (which is to say, out of molded lava). Heat is actively pumped out of the tank to run the turbines from the bright green layer in the image that forms a sort of inner tank. The system needs to keep that tank near the temperature that is best for the working fluid the turbines use.

(The notes on the SketchFab model talk about that. I have been told some of those notes run off the screen. If that is happening you can make the model full screen by clicking the icon of two arrows in the bottom right corner.)

The model doesn't show all the reflective insulation that goes all over (among other things - it is far from finished). Heat lost by infrared radiation can be reflected back by metal foil. By using two or three layers of it, heat loss can be hugely reduced in a vacuum environment. Aluminum reflects back about 90% of the heat that hits it, silver reflects about 97%. Since it only takes a microscopically thin layer to do the reflecting, we might as well use silver for all the radiant barriers. This ability to control heat loss makes this whole system work a lot better. "Don't try this on Earth" (heh heh heh).

Heat stores are more efficient the larger they are. Heat spreads by diffusion, so the farther it has to diffuse to leave the heat store, the smaller the fraction that leaves. Thus Sigvart is advocating for a Nuclear Lava Lake. His simulation program reports** that a lava store 2 km across would lose only 3 W per m<sup>3</sup> over an entire night, which is pretty sweet. Also, a lava lake is pretty sweet, if you can manage it. We didn't talk about how deep it would be. His program doesn't consider depth at the moment. I have imagined the future colonists asking the robots that built the lake how deep it is, and the robots responding "Who's asking?". There is a small mountain to the south of Lalande that likely has good highlands feedstock for glass production, we could mine that for the glass for the city and then fill in the resulting hole with the lava lake when we are done (or rather, when the robots are done). Sure, let's do that. Oh, and the nuclear part? Sigvart suggested a 'controlled nuclear meltdown' to supplement the lake's output. I have to ask him about the details, he has been busy since then. I suppose basically one lowers a nuclear core into the melt and the flow of lava around it distributes the heat and that basically works. That could be alright i guess, although that lava is useful for other things and it would be nice if it wasn't radioactive so some can be tapped for use in industry. Nuclear Lava Lake Park has a nice ring to it, though.

So now we are trying to rough in some details like what the working fluids should be, sizing of the different pieces, and more turbine design. The turbines shown are really just placeholders right now. I am leaning towards trying to get this power plant model developed, together with a tether complex model, and improvement to the colony habs, and then make those the showpieces for a campaign to go to the next level. That should be enough to take the concept on the road and try to put together the alliances needed to assemble a dedicated team to complete the core of Moonwards. I think that goal is a reasonable one, but that we couldn't go much further without an actual staff.

People have started to appear and take an active role in working on this. It's really pretty cool. It makes me keenly aware of the need to provide them with better tools and work much harder on communication and coordination -but it's very cool. As the virtual colonies themselves reflect, the approach here is to Go Big. The Wiki section of the GitHub repo will start getting its overhaul next week, in which sections devoted to resources for the key models - the solar thermal plant, the tether complex, and the main habs - are created and developed. The repo will hopefully start behaving like a full repo, with issues, projects, and pull requests. It totally deserves to, Moonwards is a great idea. It's just a question of creating the medium in which it can grow.

**Note: If you download the program, compile and run it in a terminal with this command: g++ -o gradient temperatureGradient.cpp && ./gradient

On Glass Bubbles and Being Grounded

noreply@blogger.com (Kim Holder) — Fri, 28 Apr 2017 16:23:00 +0000

I couldn't get along without windows. I don't care how big the cave is, how realistic display screens are at projecting pleasant outdoor scenes (holographic? well, that would help, but still), or how much time i spend outside (and i don't think it would be more than 10 or 15 hours a week) - big windows on the Moon make a big, big difference. I wouldn't expect people to have any enthusiasm at all for living there unless they have lots of natural sunlight, broad vistas, and can spend as much time looking outside as they like with no concern about radiation. So, we need to be able to make lots of glass there. LOOOOOOTS of glass.

Let's not get hung up on the fact that it would take decades of previous large-scale development to get to that point. Why would we go at all if that wasn't the long-range plan? The farther into the future one thinks, the less need there is for people to be in space. It gets ever cheaper and safer to have robotic equipment do work instead. If we are there, it will only be because we want to be there. The argument for making the effort becomes stronger, in fact, the more people have that desire, so let's cut to the chase. Most people will not live in a cave, or under artificial lighting, or under any conditions less appealing than life on Earth. They wouldn't give up Earth unless their new home can offer an experience of equal quality. So, we'll need to make transparent domes so huge the space within offers the feel of the great outdoors of our home world. Clearly we'll need to work towards that in steps, creating ever larger windows until those windows are a large fraction of the enclosures protecting living spaces, and then make those spaces huge. The dome planned for Lalande City requires about 4 billion tons of glass.

The issue is silica - SiO₂, silicon dioxide - the stuff available all over Earth as sand that in most cases can be used with little alteration to make okay glass. There is no silica sand on the Moon. Sure, there is plenty of silica - it's nearly half the mass of the lunar crust - but it isn't pure. It's mixed in complex minerals. So we have been searching for a way to purify what there is into the good stuff. I believe what follows would work, though it probably needs considerable tweaking.

1. The first step is to produce pure olivine. That is relatively straight-forward - as long as you have a sizable solar furnace, something you want on the Moon for all kinds of reasons, anyhow. By the time we contemplate major glass production, there are a variety of large ones and at least one giant one. With this you melt a quantity of regolith containing olivine - which it almost all does. If you are able to reach bedrock (which the colony has by this time and is using it for various purposes), with some rooting around you can probably find a deposit of dunite. That is over 90% olivine to start with. Melt it thoroughly, then pour it into a centrifuge.

2. In 0.16 of a gravity a centrifuge really isn't hard to make. I look forward to seeing what wonderful low-friction bearings can be made in such a place. At about 1200°C, olivine crystallizes while the rest of the melt remains liquid. On Earth, these crystals will sink through magma if nothing else interferes. On the Moon, because the gravity is so much lower, that might not happen. So the centrifuge helps by creating enough of an outward pull to cause materials to separate by density. Once you figure out the best temperature and artificial gravity to use in this process, you can get a layer of pretty pure olivine packed against the outer wall of the centrifuge vessel. Since the dissipation of heat can be reduced simply by using foil that reflects radiated heat back into the centrifuge vessel, the number of g's of artificial gravity needed could be low, as there is more time available for the crystals to collect before the the lava cools too much. A layer of pretty pure olivine gets packed against the outer wall of the centrifuge vessel.

Spinning exerts a force of a few g's on the lava, throwing it against the vessel walls (shown in a cutaway view)

3. Once all the olivine has solidified, pour off the remaining molten material in the middle. This will need to be done at a temperature not far below the melting point of olivine, otherwise further minerals will begin to crystallize and settle out. Set this material aside. Open the centrifuge vessel - it splits into two halves that are lined with graphite, allowing the tube of stone inside to be popped out easily.

4. Melt the olivine again. It is is still composed of two minerals: fayalite - Fe₂(SiO₄), and forsterite - Mg₂(SiO₄). Fayalite crystallizes at a temperature far below that of forsterite. It is what causes crystals to form of sufficient size to sink in magma deposits on Earth. That is what this whole concept is based on - how minerals are known to separate on Earth under certain conditions. So perhaps this is a good time to mention certain unknowns due to the fact that the Moon is not the same. Magma on Earth normally has a higher content of silica - that's why we have this problem in the first place, the Moon doesn't have enough silica for it to aggregate as a pure mineral (quartz) at the end of a magma crystallization process. Silica prefers to bond with other metal oxides, and only crystallizes as pure quartz when all of them are gone. Magma with more silica is more viscous (less runny). Earth magma has a lot more sodium and potassium, both of which make it less viscous. Raising the temperature of a melt more will make it runnier. Because the melting point of forsterite is a full 700°C above that of fayalite, at some temperature below forsterite's melting point, and at some rate of centrifugal acceleration, the fayalite will be runny enough to sink through the forsterite, which will form a crust on top of it. This for me was sort of counter-intuitive (so much so i got it wrong and am fixing it now with an edit). Iron is a much heavier element than magnesium, so even though the fayalite is liquid and the forsterite is solid, the fayalite is going to form a layer under the forsterite because it is denser. So now you can't simply stop the centrifuge and pour off the liquid contents. If you stop it, the crust of forsterite is going to break up and mix with the liquid fayalite, contaminating it. Hm. There are two options that seem plausible. Drain the liquid through taps on the centrifuge outer walls, stopping before the forsterite layer gets too close. Or, let the whole thing freeze, and then cut the fayalite layer away from the forsterite layer.

5. Now we are getting somewhere. Pour the fayalite into a fluidized bed reactor and bubble hydrogen through it. It will react to form water, iron, and silica. The water forms steam which is continuously pumped off to keep the pressure in the reactor low and the reaction going nicely in the desired direction. As more water is removed, the melt will tend to solidify unless it is heated further. Iron melts at 1538°C, and silica at 1713°C (both at 1 atmosphere). The more the mix is depleted in oxygen by the reaction, the less the iron will combine with the silica. Once no more steam is coming off the mix, let it cool to below the freezing point of iron, and the iron will sink to the bottom of the reactor. Pour off the silica. Reheat the iron so it melts, and pour it off too. (Note: there is a 2nd candidate reaction to perform this step - bubbling oxygen through the melt to produce magnetite and quartz. Possibly that would be better, and it will also be documented when all this is added to the regular contents of the website. I chose to describe the hydrogen reaction here as it is a bit less complex and also produces iron, however if it is too slow or doesn't sufficiently purify the mix, the oxygen reaction may replace it. Recycling the hydrogen by splitting the water molecules may be easier than getting more oxygen, that is another consideration.)

6. Okay. Remember how i said you could start with dunite, which is almost all olivine? Actually you might want to avoid that, unless you need extra of the products of the above reaction, which you certainly might because all the products are darn useful. Even the forsterite - you could make crucibles or refractory bricks out if it. Otherwise, it could be a lot more efficient to seek out highlands material that is a good mix of plagioclase with pyroxene and olivine. Stuff that's about 60% plagioclase with the remainder mostly olivine would do nicely. Finding something like that should not be hard. In that case, the stuff you poured off in the first step can now be added to the silica you produced from it, and the ratios will be right for alkaline earth aluminosilicate glass.

7. The ratio of silica, to aluminum oxide, to alkaline earths (calcium or magnesium oxide) needs to be close to 12:5:3. Once the melt with the extra silica has been reheated and mixed, it can be poured into molds, blown into shapes, or extruded through rollers. The roller process is the one that is the key. Taking advantage of the vacuum and low gravity once again, chilled rollers continuously fed by a vat of molten glass maintained at the right temperature can be used to produce plate glass the way they did in the old days.

A critical piece of information that is currently missing is how long you have to cool the molten glass from its working point to its annealing point before crystals start to appear in it and make it cloudy. (It will be necessary to contact a manufacturer to get that information, but i wanted to post this before then. I'll edit in the data later.) The time must be quite short, as the only thing glass with this chemistry is used for on Earth is as bulbs for halogen lamps and other applications where it can be cooled very quickly. Massive rollers chilled internally by liquid coolant can get that job done. It's just a matter of setting up the system with the right feed rate and rollers that are big enough. Because the operations can all be done in a hard vacuum, it is relatively easy to keep the vat of molten glass at the right temperature while it empties by using reflective insulation. The vacuum also ensures there are no dissolved gasses in the melt to cause bubbles. The rollers need to be cold enough that the glass is almost solid when it emerges from them, but the glass will still be about 900°C. In that case, it isn't so hard to use radiators and heat pumps to keep those rollers chilled.

If the resulting glass is more than about 2% iron, it will have a green tone visible enough to be distracting. Not nearly as distracting as living with tiny windows, but not ideal. Of course, the lunar landscape is not exactly brimming with color, so that may be a pretty minor point. If there is still a percent or two of magnesium, that is hardly a problem either. Magnesium oxide is an alkaline earth, as long as the ratio of those is right, it doesn't matter if it is made of calcium oxide, or magnesium oxide. Nothing else that is even slightly common in lunar soil presents any problems either. I'm telling you, this will totally work.

Which makes me feel a whole lot better, because now i'm going to proceed to detail our giant glass-covered city, with all the trimmings.

Edit - This post was improved to reflect better information when inaccuracies and unclear passages were pointed out to me when it was first posted yesterday. I really appreciate it when people take the time to do that. This person did so in our chat room on space.stackexchange - the address of which i'm about to add here in the sidebar, as well. Thanks to MolbOrg for that assistance. Further Edits - fixed viscosity - more SiO2 makes glass more viscous, not less. Fixed description of separation of fayalite and forsterite, to reflect that fayalite is denser.

Timeline to the Space Boom

noreply@blogger.com (Kim Holder) — Thu, 30 Mar 2017 20:18:00 +0000

The timeline for the virtual colonies, it turns out, is not the digestible list of bullet points i thought it would be when i started on it a couple of weeks ago. It is 130,000 words, and i stopped myself before it sucked me in completely. It maps out how the whole society on the Moon works, how a very achievable set of technologies supports it, and how the colonies develop industry and agriculture over the course of 50 years - in a dense but readable format. Outlining decades of humanity's greatest ever undertaking can't be done much more briefly. That's my story and i'm sticking to it.

It all has a pretty Utopian feel. The whole project rests on what could be done if there was a determination to do it, a Utopia just sort of springs up from that. I think that's okay. Resolving the conflicts that perpetuate suffering in the world depends mostly on creating a sense of brotherhood. The best way to do that is for people to work together to create something. The harder they work together, and the more inspirational the result is, the greater the sense of brotherhood afterwards. So it is useful to present a picture of just how awesome our deeds could be if we acted together as a single species, united in the pursuit of a shared goal. By that i mean awesome in the original sense of the word, of causing awe, something that a person only really experiences in their life a handful of times, if they are lucky.

At any rate, the timeline uses a program where the space-faring nations unite to build the first installations. That culminates in the transport infrastructure and construction capacity for spacious habitats. Then it sells residence in those habitats to nations to recoup the cost of that construction while acquiring a highly skilled and dedicated work force at the same time. For a price of US$300 million, any nation may send 2 astronauts to the Moon for the rest of their lives. Those astronauts must meet a list of stringent qualifications, including a strong background in science and engineering, and sign a contract for life to work for the International Space Agency in exchange for permanent residence on the Moon, in an environment that sustains all their needs. Over the course of 25 years, it recruits 25,400 astronauts in this way, with the cost of a spot in the program dropping by half while the number of spots doubles in each of 7 rounds. I shall leave it to you to go read how that many people are transported, lodged, and sustained in a way that could actually work. The point i want to make here is it strikes me as probable that people who live together that way for that much time will become quite adamant it is the way people ought to live - working together and sharing everything.

Add to that the way they are socially organized and you get a lovely neotribal society. Because for most of the Residence Program water is scarce, food and power limited, and everything must be recycled carefully, the astronauts are always split into groups of 30 to 50 who all share one large kitchen with one pantry, one set of showers, and one washing area for clothes and such. By the time the program ends, it has become a firmly established cultural preference to remain organized this way, and even to continue sharing kitchens and baths though the need disappeared long before. Administration and conflict resolution becomes centered around these micro-communities. When people start having children, it becomes focused around these groups even more. After all, the pseudo-tribes have lived with no children around for decades, so once a couple in their group has a child, they all want to be uncles and aunts. And the children are thus raised very communally. Moon society recovers the strength in social bonds provided by a tribal society, while keeping all the strengths of a nation-state system based on technology. Snap! I rather adore it.

Once i return to working on the 3d models of the colony, i'll build a few examples of what i mean, about that kind of living situation. I think that would show how well it can tap into our ancient instincts for those kinds of bonds and become second nature in no time. It will be a fun concept for people to explore within the virtual colonies, and actually may be a useful organizational tool there, so that when people start modeling homes, they become groups themselves.

Just as our futuristic tribes-people are hitting their stride, the snowball effect of robotic construction and cheap transport unleashes The Space Boom. It is said that the human mind can't naturally appreciate exponential growth patterns. Plotting the activity of a virtual Moon colony apparently helps, based on personal experience. The more i work on this, the more i think a principal task we have before us as human beings is for a critical mass of us to understand something: that space becomes incredible soon after the moment we become able move about it with ease, and the results will changes who we are forever. Some other really vast technological achievement (read artificial intelligence) or some vast complex mechanism built to save ourselves from disaster (read geo-engineering to fix the climate) could change us forever too, but doing this in space would be the preferable venue. I think you can see why.

One of the great things about the Moon, for instance, is that you can build all the robots you want (or rather, have the robots build more robots), and make them pretty intelligent too, and it is no problem. Nobody loses their job, not a single blade of grass is damaged. (On the contrary -they plant lots of new grass.) If self-awareness appears spontaneously or is engineered, and gets screwed up, there is 380,000 km of hard vacuum and two gravity wells between those machines and the rest of humanity. And we really do need to think about such things. So note that if it is done well, Moonwards' virtual colonies would be a great place to explore that in a way that doesn't totally freak people out, while also getting them to learn about it in an engaging way.

We have reached a point, we humans, where we need a better societal model. Utopia is fun to think about, and doing so may sincerely help one be created, but the stakes are higher than that right now. We have powers already we are not mature enough to responsibly exercise and more such powers are arriving almost by the year. The longer we operate in social systems that can't adapt and even becomes highly distorted by these new powers, the greater the risk of catastrophe. This is widely sensed, this is why so many great thinkers warn this could be our last century, while other great thinkers say Utopia is just around the corner. It would be nice if modeling a new way of life in an entirely new place helped people see how much greatness is already in our hands and how feebly we have been directing it. We can do so, so much better.

Also i'm hoping the fleets, and giant space stations, and the giant domed city built by robots there in the far end of the timeline - that it is all exciting enough to pull in the people who can make that virtual world come vividly alive.

Ice Mines Don't Sell

noreply@blogger.com (Kim Holder) — Fri, 16 Dec 2016 16:50:00 +0000

Kapitalist asked if Moonwards could also work on a plan that could happen in the world we know in a comment on the previous post. That was like pressing a big red button in the middle of my forehead, so i am responding here.

If we only think about what could be realistically done under existing political realities, we fail to see the real nature of space exploration. Decisions about undertakings of this scope should be made knowing the best and worst possible outcomes within our lifetimes. This is really important, but the matter is almost completely neglected. That's because we haven't had the tools before to really examine it. Now we do, and time is of the essence.

Paul Spudis has a wonderful detailed plan for lunar exploration, in my opinion the best out there by far, very realistic and reasonable. I have to ignore it almost completely. There is a list of reasons. I will look at the main three.

One, you can't sell ice mining to the public. I mean, maybe they'll shrug and say 'whatever, yay Americans in space', but there will be no new enthusiasm. It's like the ISS, but with wet dirt. Not interesting if you aren't a space nerd. Paul knows this. He has astutely designed something that can be done within the existing budget.

Two, it leaves out in the cold the many key facts known only to space nerds, a constant source of frustration. Nuclear ships are safe and the technology is ready, but nobody dares use them. Development of tethers would not be that hard for use in lunar orbit, and the payoff would be massive, but it is an unexplored road and everyone wants to stick to the safe, known things because budgets are lean and government types are skittish. The Moon has gigantic military potential once you are there and settled in. Really, gigantic. There is a tipping point beyond which activity in space will suddenly explode, that point may be much closer than almost anyone realizes, and it will change the world profoundly. People need to know these things. It's important.

Three, the world needs a new way of being, and it needs help finding it. The world we know can't continue the way it is. We have done pretty well, for such a young species. But we are becoming very powerful very quickly and we are ill prepared to handle that kind of power. The planet has become more peaceful over the last century but is an awful long way from being peaceful enough for me to be comfortable with a slew of technologies that we already have becoming commonplace around the globe, never mind the technologies just around the corner. Moonwards may not seem relevant to a search for a new societal model, but it is. Once it is actually modeling a society on the Moon, that will become clear. That has to be done extremely well in order to work, but it can, and if it doesn't, it will show a path forward that will.

This bit has been very hard to convey. Living in space is the goal here, the only thing the public really cares about. And they are right. That is the thing that will change who we are. Who will we become? Will we destroy ourselves? Will we devastate our environment? Will there be a powerful elite and a mountain of poor? Will we be free? Will we be people we could respect and admire?

Space science fiction looks at this, but through a glass darkly. We need to look at it directly and really think it through as much as we can before it actually happens. I'd say we likely only have 30 years.

Colony Expansion

noreply@blogger.com (Kim Holder) — Sat, 03 Dec 2016 22:06:00 +0000

Sketching things rapidly is really helpful for discussion. In the last 3 weeks i've sketched all the main installations of the colony in order to create an overview, and a framework that can be the basis for improvement. There are still a number of undocumented things, nonetheless there is so much more in the colony models i'm having trouble deciding how to explain it. At the same time, the models are such simple sketches, they don't really get across the richness of the ideas unless the viewer fills in a fair bit... Let me see if i can paint this picture for you now with what we have...

Whole Phase 1 colony looking west over the crater rim

The developed area is 2.5 km north-south (1.5 miles), 4.4 km east-west (2.7 miles), and 1.3 km (0.8 miles) top to bottom, plus the things not in the image, which are the space port and the second solar-thermal power installation, each of which are a few kilometers further away. This is the colony known as Cernan's Promise, at the full extent of it's development. Which is to say, this is the full extent that will be modeled as a complete virtual environment. The scale of it makes it hard to show people - it's like showing photos of your vacation. This perhaps can get across this odd threshold i've crossed. To me, this is a place. I built it, i've spent hundreds of hours doing so in its virtual space. And it is still a pale shadow of the far more complex and complete version in my head, as i have not yet been able to create all that. At the moment, i am the sole citizen of Cernan's Promise.

This shot looks north from the south end of the colony. At bottom right is a section of the glass and basalt composite dome over the small crater i call Teacup Crater, which is 300 m across (yards are 10% more, so 330). That dome alone could be an entire blog post. I plan to do a series of such posts, for now suffice to say that real colonization is going to require domes like this, so we might as well dive in. We are modeling the beginning of a Moon civilization here folks. This is the scale that will be involved and we need to adjust to that, let it sink in.

Shown in the bottom left is the first draft of the main version of the rover, which is a slight adaptation of the ATHLETE rover. It can do a lot of the coarse construction work, using a wide variety of attachments that can go on the ends of its legs - JPL designed it that way. This venture involves construction of a complete colony though, so it is going to need a supplemental arm capable of more detailed work, and smaller robots that have little mobility of their own will be delivered by it to work posts it installs, again for the purpose of performing the detailed work. People on Earth and at the polar settlement will operate them.

Behind it is the gantry crane, which is copied from the NIST spider crane. I think it will need to be switched to a square configuration, but it has great advantages as a lunar crane. The platform at its center is currently empty, but will bear a robot that can be moved anywhere within the volume below the triangular frame of the crane, down as far as the cables reach. Here it straddles the width of one of the dugout habitats, to show one way it will be used. It will do the excavation of the dugout and gallery habs. It will also be useful in assembling and erecting large structures like the hangars, mirror troughs, and radiator stations. Many of those are visible in the middle ground of the picture. In the top corner is the hangar of the space port.

This shot looks southeast from the north end of the colony. Most of the hangars are visible from this angle. This colony is an industrial center. After the initial phase of settlement, which is funded by selling permanent residence spots to nations, the economy is based mostly on in-space construction. That allows a great reduction in reliance on Earth for supplies, which is a huge cost savings, and provides income from selling services and goods to Earth that space construction makes possible. The colony builds space stations, space ships, and orbital tethers. That is why there are many very large hangars. Most are just covered spaces so that the interior is free of dust and stays within a narrow temperature range - they hold no atmosphere. The ones with the rounded ends, that don't have the reflective insulation on their roofs, contain an atmosphere about 0.1% that of Earth, so that heat dissipation can occur at the rate needed for production of basalt fiber.

The complement of melt-in-place stations fill the middle ground. Their beds get filled with tamped and leveled powder regolith, then a Fresnel lens scans the length of the bed, melting it to a depth of an inch or so. Just before the material solidifies it is cut into shapes. Those are the construction materials used to build most things shown. The construction method is explained further on the website. It is due for a lot of updating, but basically it is all there. The main papers the concept is based on are part of LPI's Lunar Bases and Space Activities of the 21st Century - James Blacic's Applications of Lunar Glass Structural Components, and Rowley and Neudecker's In-Situ Rock Melting Applied to Lunar Base Construction. It's been plucked from a few other places as well - one of the many things i need to document better. What i'm trying to say is - this has all been thought through. It is only different from other lunar settlement concepts because it assumes a high level of ongoing funding. That assumption naturally leads to new and exciting vistas.

Vistas like this one, from inside one of the tubular habs branching off the lower gallery - the galleries are the long habs descending the slope of the crater wall.

Panaromic views like this are alright when they are of the ground. Very little particle radiation backscatters from the ground - that is what cosmic radiation is, particles, that is the long term danger. EM radiation - gamma, x-ray, alpha, and beta - can be blocked with a few inches of glass doped with a dense element like platinum. Yes, platinum. By this time asteroids are regularly arriving in orbit to be mined, platinum would be a cheaper and better metal to use for radiation-blocking glass than the lead that is used today on Earth. Bulk production of clear glass is a high priority, too. If you manage that, then you can do this:

Yeah, the image doesn't really do it justice, but that is a glass dome over all of Lalande Crater. 22 km across. The blue towers are 75 m wide. Not only do they distribute the load of holding down the dome against the strain of the atmosphere inside, they are buildings. Each one can house thousands of people. Sure, you need to develop the infrastructure to fabricate enough glass for a dome at least 5 m thick over all of this. But the payoff doesn't need to be explained, the outlay doesn't need to be justified. If we could do this, we would. Even if it meant a lot less of our disposable income went to other non-essentials like fashion, treat foods, sport events, booze and cigarettes. If we could do something like this, we'd be willing to let go of a few things like that. Like we were willing to do during World War II, but for a much healthier pay-off. That is the premise of this project. If the vision can be painted clearly enough, if the path can be explained completely enough, the will to pursue it will appear. And even if it doesn't, it will be a great vehicle for pondering where we are going, and why.

Don't kid yourself. It is outlandish now, but the ability to do this could appear much faster than we expect. If robots that can work with little direction are developed, we'd only need to send a few and it would snowball. It is the kind of thing that can suddenly be upon you, changing the world while you are still deciding if you think it's a good idea. This is a great time to work on a vision that can ensure the future is positive.

Walking on the Moon

noreply@blogger.com (Kim Holder) — Mon, 07 Nov 2016 23:49:00 +0000

I have spent a lot of time in and around Lalande Crater on the various maps of the Moon. I have my favorite spots. I've developed an inordinate fondness for it as clearly one of the handsomest craters. I have burning questions about what is really there. So, when i decided it was time to make a 3d model of it using LRO imagery and topographical data, it isn't surprising this activity stretched to over a month.

I highly recommend the modelling of craters as a pleasant pass time. If you enjoy maps and scale models, you will find it rewarding. We have a whole Moon covered with craters for which such models do not exist, so you can also enjoy the fact the result is a first and might be useful to someone. Really. There are very few such things in existence, and what there is isn't very detailed. NASA (of course) has the best collection, but the size of the smallest details in their models is still on the order of 100 meters (300 feet). Also, all the listed models at the link have been stretched vertically for dramatic contrast, which makes me shudder. Cosmetic fixes like that aren't necessary if you lovingly detail a smaller feature by using photos for reference, instead of modelling areas a hundred kilometers across using only topographical data. LRO photos have resolutions as small as 50 cm per pixel (20 inches). With them you can show off the Moon's actual rugged terrain, as it really is. But, it takes time.

The LOLA laser altimeter on the Lunar Reconnaissance Orbiter is an exquisitely accurate instrument - attached to a probe moving at orbital speed that has no way to precisely calculate its position. Thus, the fact is LOLA topographical data is very coarse and full of artifacts. Step one is correcting those.

No, there aren't actually any ruler-straight lines cutting through this crater, or any pancake-flat mesas on its rim. In fact the LOLA data was only good for establishing some base-line reference points at key spots where one could be confident the data was accurate. It is mostly useful for large scale stuff. I was grateful a friend had passed it along to me though. I undid the imaginary mountains and gullies by hand until a very rough but basically accurate shape was created.

Step two is to download some of the wealth of LRO close-ups of the lunar surface and stitch together an image you will lay over the 3d model. This step can take a long time if you are fussy. The LRO has taken images of Lalande from different orbits over time, and the changes in altitude changed the perspective in the shots. There is more foreshortening in the shots taken from closer, which leads to a difference in apparent location of objects of a couple of hundred meters in many places. In movies, 'vertigo shots' use this by moving a camera on a dolly towards the subject while zooming out at the same rate. Here is an example i especially like:

Once i appreciated this, there ensued many days of painstaking warping of the shots taken from closer to mold them to the perspective in the shots taken from farther away. The seams between sections are not perfect, but they are as good as i could make them in a time frame that made any kind of sense at all. The Blender 3d program can be used exquisitely to perform this task, once one figures out how, which in my case took quite a while. If i were to give a tutorial to others on how to do it, i could convey a polished version of the process, the one i developed over many days of frustration, and then those others could quietly enjoy repeating the process on other craters while perhaps listening to an audio-book or chatting. I, instead, struggled most of the time to understand why things weren't working and trying to sort a bunch of different versions each with many layers. Now, after it's all done, i've gone back and admired the nearly perfect alignment of images on the Quickmap LRO collage of Lalande Crater. They must have a program that takes all the LRO data associated with each image file and uses that to correct their proportions and project them onto a virtual globe. Lucky sods. There are still misalignments - my manual alignment is about as good. It took me three weeks, but if i did it again i could do a better job in maybe 3 or 4 days. If you, dear reader, undertook to build your own crater model, you might prefer to simply set up Quickmap with the image layer of the desired crater that has the least shadows, and take grid of a couple hundred screenshots of the result in the top resolution, and then patch those together. It would be about the same amount of work but at least it requires a lot less concentration, so you could enjoy a nice podcast while you work, or some such. Oh, by the way - don't attempt this unless you have a computer built for heavy graphics work. It took mine 15 minutes on many occasions to complete a command, and it is built for this kind of thing.

Step 3 is to take the final image and use it to refine the rough LOLA model. This is where you will really appreciate having your highly detailed and accurate image to work from. You can paste it onto the surface of the rough 3d model and line it up in good registration with it, then sculpt straight up and down where the image indicates rises and slopes. A supplementary reference from the side is really useful here. The Apollo photographs from orbit are pure gold at this stage. This one a friend found for me is one of my all-time favorite pictures:

For now i have recreated only the main contours of Lalande. I look forward to quietly adding detail when i have time, or when i feel a need to ruminate for a while. All sorts of things are happening within it. Why do a series of domes well up across the crater floor? What about these things that look like burst bubbles as large as one of those domes - is that an indication the domes could be hollow? (Edit Dec 6: Paul Spudis thinks that is highly unlikely, and that the blister shapes found on the floors of young craters are probably caused by large chunks of ejecta protruding from the surface of the melt.) This thing looks like an old lava vent - could that be what it is? That long sinuous crease in the floor, leading away from a large secondary crater - why did that form? Could there be a lava tube underneath the surface there? There are large areas of scree on the steep upper crater slopes - will there be lots of clean chunks of bedrock in those fields? Why is the northern spur of the central mountain so covered in boulders, and in particular on its western slopes? Walking around in the 3d model stimulates speculation...

So now i need to update the 3d model on the website, which right now is an old, less accurate model. The crater walls are very steep near the rim, it took me a while to get that right, and still it is only done for the patch below the site of the colony. And then i can move on to putting in sketches of all the infrastructure planned for further out, to have a general overview of the project. Which should be much more fun. I did a short fly-through video of part of that model, there will be better ones later when i get the hang of it more.

I have promised myself i will spend no more than 2 weeks completing the rough draft that will go on this 3d map i've spent a month building. I am very prone to fiddling and fussing. It is time to start spitting things out so a broader dialogue can be started about how things should be and what we should work on. But it is nice to know i can put in my little stick-figure buildings and installations on a beautiful and accurate model of Lalande crater. It just makes me feel better about the whole thing. :)

P.S. The final image i created was 40,000 pixels square. Here is a tiny version of it:

(Edited Nov 8 to properly give kudos to Quickmap.)

The Transport Tipping Point

noreply@blogger.com (Kim Holder) — Wed, 12 Oct 2016 20:06:00 +0000

Giant rockets and giant rocket explosions have been all the buzz for the last few weeks. It has gotten me thinking how little conversation there really is about the future being pursued here. There is lots of analysis of the market and the technology, but not of where we are headed. Sure, the viability of colonizing Mars is discussed, and the reasons for pursuing space settlement in general. But there is no sense of how scale affects the whole thing, and changes the whole panorama.

There is contemplation of key projects that would expand the launch market enough to spur other development, but each such plan has major weaknesses. Space solar power can't work unless it would be cheaper and better than covering a fraction of a few deserts in solar thermal power plants with underground heat storage, which it wouldn't be. Lunar propellant production needs a market to already exist for that much rocket fuel to make sense, and instead of that being a growing market, the existing market is switching to fuels the Moon can't provide. Space tourism seems the best bet but would likely be gutted by one fatal launch accident.

Elon is right, the only way to cross this bridge is to take people to live on another celestial body. He has just picked the wrong one. We can argue all day about the logistics of water and fuel. Logistics is not the point. The point is The Reason To Go.

Elon has leaned hard on the idea we should be a multi-planet species, if only for safety reasons. Well, let us look at the possible ways people could be wiped off the face of the Earth in the time frame it would take to create an independent Mars colony. You have your asteroids and your super-volcanoes. Those are both slim chances. If we get wiped out it will be us who does the wiping. We have been waging less war recently, but if resources become scarce that will change fast. I don't think we'll kill ourselves off, but it is a great way to make the point the reason to go to space is to change Earth. It will take a large cultural change on Earth to remove the risk of devastating wars, and simultaneously free the resources needed to make all our lives much better. That can be done from space, but you have to stay close enough to home to have that impact. So, go to the Moon.

We can all agree changing our future is what we are trying to do, right? All of us in the space community are trying to lift the collective gaze of humanity from our petty thinking to the boundless expanse of the heavens. That gaze will not stay lifted unless people can SEE something out there and feel they might be able to reach it themselves if they try. And now let's contemplate how much accessible water, carbon dioxide, and nitrogen in huge quantities on Mars matters, if the goal is to get people to another world where they can live happily for the rest of their lives at a price many could afford: it doesn't matter one bit. Because it is all about the transport.

The irony of the owner of a rocket company failing to see this is rich indeed. Especially one who has correctly nailed reusability as the key to everything, and advanced so far towards that goal. I wonder if slapping him a few times would help...

The entire point of SpaceX's Mars plan is that by making the cost of transport really cheap, you can get the massive payloads needed out there within your budget. Unfortunately, you can only launch every 2 years, when Mars is in the right spot, so the advantage gained is limited. You can launch to the Moon at any time, though, and not only that, the same ship will be back in LEO in only a week to be reloaded. (Slap.) What do you care if you have to add a bunch of trips so that you can send all the water, carbon, and nitrogen the colony needs? Your launcher is reusable. The more you use it, the cheaper each trip is for you. Your whole business plan is based on that. (Slap.) In fact, you couldn't possibly use it to load Mars ships enough times to make that pay off, to leverage that benefit 95% of its payloads would need to be going someplace else - even if the launch market for Earth satellites was several times the size it is today. In fact - how are you supposed to make the money needed to create the giant fleet for your Mars city? Where is all that business supposed to come from? You know what you need in order to have that much business? A destination that is only 3 days away, at any time. You need the Moon. (Slap.)

Besides, if you aren't sending people with all the food, water, and other supplies needed to live for several months in space, then you have freed up the payload you need to send enough supplies for them to live on the Moon forever. Because it will need to be a closed ecosystem, so send the food for a Mars journey instead as stuff to enrich enough lunar soil into garden soil to support one person, and you're done. (Slap.) But wait, why would you endlessly send basics from Earth when you could go catch some near-Earth asteroids, put them in lunar orbit, and get all that stuff from them? And since you have been studiously working on collapsing the cost to LEO by two orders of magnitude, the precious metals that would also be in those asteroids could be profitably returned to Earth and help finance the venture. I will forego the virtual slaps for that, and for not considering that the transport costs between LEO and the Moon can be vastly reduced again by developing a system of tethers between the two worlds, because that depends on things that aren't directly implied by the very transport system SpaceX is working on. But the ITS does imply the ability to move massive amounts of stuff around space, so if that was used to build a city on the Moon instead of Mars, it is easy to see how you could use that city and your ships to then build other things in cislunar space, such as space stations, more space ships, space-based solar power that actually makes sense, satellites. And since you made the Moon city possible, you would have a stake in that and make money off it, whereas there is no possible business model with a Mars city, other than the city itself. (Slap.)

Is a Moon city harder to build than a Mars city? No, it is easier. The first structures can be built by robots operated remotely from Earth, a technique not possible on Mars due to the signal transmission time. That also means you can get much more out of each kilogram of payload you put on the Moon before people arrive, and when they do, a big beautiful place will be there for them, not a few tin cans with dirt heaped on top. Which means those people are a lot more likely to stay, and live happily, and do great things. Great things that impact the Earth, because they will be just as connected here. They will tweet and game and make phone calls and post photos and videos and stream stuff and surf like they'd never left. On Mars? Nope. Eventually they will go back and forth regularly, and lots of people will visit. So don't talk to me about how Mars has more resources. The Moon has big-time resources where it counts - 7 billion people 3 light-seconds away, to whom the Moon is relevant, and Mars is not.

By far the easiest and best place to make a city where you could take people for a few hundred grand to live for the rest of their lives, happily, and not go broke, is the Moon. Also, you might save the Earth while you are at it. Stop it with this Mars stuff. It makes no sense.

(Note: while it may seem that i get undue pleasure out of visualizing slapping Elon Musk, that isn't true. I would be just as happy slapping Robert Zubrin.)

Nice Even Temperatures Through the Magic of Thermal Mass

noreply@blogger.com (Kim Holder) — Mon, 03 Oct 2016 00:36:00 +0000

An entry came in on the website forum about the extreme temperature swings between day and night on the Moon, and the difficulty of keeping temperatures even because of this. The poster, Sam D, mentioned in another post how lava tubes help with this, and that is indeed one reason why the idea of just sealing one up and using it as a hab is popular. I haven't ever properly explained why the habs we've designed will have very stable temperatures, so, now i am. (There is a different version of this on the forum more tailored to the asker, here i'm rearranging it a bit.)

If you have enough mass within the whole gallery space, then heat regulation is easy. Just make sure that enough heat leaves over the night to balance what came in during the day. That will mostly happen through the rock of the gallery floor and lower walls. If anything, the windows won't be enough for that and very minimal radiators would need to run every now and then at night.

In the Gallery, the heat entering during the day is what comes through the light tubes, and the water dome at the bottom, which is a small fraction of the sunlight falling on the surface covering the Gallery. Each light tube would pass in about 27 kW of sunlight all day, and there are 76 in the current design. Note that this can be adjusted at any time - shift the angle of the Fresnel lens, and the amount of light coming in can be decreased to any fraction desired. But if that wasn't done - and it would be far better not to because sunlight really feels good and makes plants grow - the whole set would pass almost exactly 2000 kW of sun in all day. The heat capacity of most rocks found on the Moon is 0.8 kJ/kgK, meaning that if that sun was all hitting 2.5 tons of it, it would heat up by one degree celsius every second. Alright, that does sound like a lot, and is the exact reason sun is going to be used to make the materials for the habs in the first place. But the Gallery is going to have a HUGE amount of thermal mass.

The image below is from Constraints on the depth and variability of the lunar regolith by Wilcox et al, and shows the estimated depth below which the Moon is pure rock. Because of our lack of data, this model could be off quite a bit, and also in the case of large craters like Lalande, the regolith at the very rim has been modeled as being twice as deep as it is in the surrounding landscape. Still, considering how far down the crater wall the Gallery extends, it stands to reason that a large portion will be cut out of solid rock (and that isn't a problem). So how much thermal mass does it have? Well, for all intents and purposes, it is a cave. Oodles.

In fact it will take time to add enough heat to the structure to raise the thermal mass that affects the interior temperature enough to reach room temperature, and extra sunlight will need to be piped in for that exact purpose. (Using lava during the building process helps here.) The temperature below the surface of the Moon is about -20 degrees Celsius, so heat will be sucked up by the surrounding rock in giant quantities thanks to that gradient. No problemo. What needs to be done is to pour in enough heat that it sufficiently saturates the volume of rock that will interact with the gallery. There is a distance from the gallery walls at which the heat coming in during the two weeks of sunlight equals the heat seeping away through the rock over a lunar month. Fill the volume of rock closer than that with enough heat to keep the gallery at room temperature, and it will stay at that temperature, cooling only very slowly over the night, but heating up again an equal amount the next day. If heat stops entering it would cool only very slowly, it would be months before the residents were at risk. And why would heat stop entering? There is no weather on the Moon, as long as the lenses over the light tubes turn during the day like they are supposed to, the only variable in the strength of the sunlight is the sun - so we are talking about a difference of about 0.1% between solar maximum and solar minimum. The only thing here is that it might take so much heat to get the gallery to the proper temperature in the first place that it takes a long time to pour it all in there. If so, a simple trench cut in the rock can be used to tailor the amount of rock involved. Any void is going to be a vacuum, which is great insulation, even if it is only a centimeter wide. Line it with aluminum foil and that makes it even better. So you can limit the area through which heat is seeping away by almost any amount.

There is a book that uses this concept for the design of houses that use no heating, but remain quite close to the same temperature all the time by balancing the sun that comes in the windows with the heat that seeps out of a mass of earth kept dry and insulated from surface temperature changes under a layer of insulation and plastic. It is called Passive Annual Heat Storage, by John Hait. The concept never really took off as there aren't many people with enough space, the inclination and money to have one built, and in spots where it isn't too hard to gather enough bone-dry earth, and keep it that dry until it has been properly emplaced and protected. However, in the examples that exist, temperatures fluctuate only by 1 degree Celsius or so through the whole year, even in places with harsh winters.

A dry earth mass extending 6 m from the house was necessary, and south-facing windows

Heat moves towards cooler spots, but it moves ever more slowly the less the difference in temperature is - the less the heat gradient is. When there is a large heat gradient and a cycle of heating and cooling, like over a day on the Moon or over a year on the Earth, places underground that are far enough away from the where the heat is changing basically never change temperature. Between that point, and where the temperature is cycling up and down, how much the ground changes temperature over that cycle smoothly increases. On the Moon, the temperature difference between the ground and the habitats would be about 41 C or so, much greater than that difference on Earth, and heat would flow through the bedrock much more quickly than it does through dry soil on Earth. The distance to where heat fluctuation ceases would thus be much further, which is why creating narrow trenched to limit the volume involved would likely be necessary.

Heat moves most where the gradient is highest

In the drawing, the pink is the powder regolith, through which heat moves very slowly so it basically functions as a layer of insulation. The grey is the bedrock layer, the red is the stored heat that keeps the hab's temperature steady. Because the big temperature difference is always going to be between the lunar surface and the interior of the hab, heat will always move mostly either into or out of the hab through its openings - windows, light tubes, the occasional airlock, and a few small radiators. So the heat in the ground at night will move mostly towards the interior of the hab, as heat leaves through these openings. It will also seep away through the stone, but more slowly because it takes so long for changes within the hab to significantly increase the heat gradient around the edges of the volume containing all the heat. The surface area involved is much greater, though, so again, we come to the matter of creating trenches.

There are many possible options for layout of the trenches, this is just one. Mostly what the trenches do is create bottlenecks to outflow of heat so more of it stays closer to the hab. At the scale of the gallery, the vertical trenches are about 35 m long, the horizontal ones 10 m, and the diagonal ones about 15 m, since the gallery is about 32 m wide (and varies in depth). So, creating them isn't a small thing, but fiber-optic cables coming from sets of concentrating mirrors will provide a great tool for the job that can melt rock very quickly. Since the gallery is on a slope, the molten rock created can be drained away simply by allowing it to flow away downhill. Do this correctly once, and down the centuries this space will never need more than very minimal heating or cooling, so it is worth it.

The light entering the sports hab is indirect light reflected off the ground outside for the first 11.5 Earth days of each Moon day. The surface of the Moon reflects very little sunlight. In Lalande, which is brighter than surrounding land, it probably reflects about 15% of the sun's light. How much heat would pass through the windows at different times of day is a complex calculation far beyond me, but think of it this way - it would be less than the heat passing through such windows on Earth due to indirect sunlight bouncing off lawns and fields. For 2.5 Earth days before sunset progressively more of the windows would be hit by direct sun, mostly at an oblique angle, so that over the course of that time maybe a quarter of that sun would pass into the hab. Water is about the best thermal mass there is, so 3000 tons of it in the pool will heat up very little due to that amount of sun over the day. It would take about 12.5 billion watts to heat it up by 1 degree Celsius. Taking everything together, i'd guess it might heat up by 3 degrees Celsius in a day. Heat is shed only by radiation in a vacuum, so only a portion of that heat would leave that space over the night. I couldn't tell you how much, that is too sophisticated a calculation for me to even estimate. But it is safe to say that after maybe 3 months, if the extra heat wasn't passed into the Gallery or shed by a small radiator over the course of the night, that space would feel too warm. Not sweltering, just too warm.

In the case of the dome, for the sake of making life easy, it would be good to put a layer of that smart glass on the outside, that changes opacity when a charge is run through it. The sun is pretty bright during the day so that would make it much more pleasant to be inside, aside from making it simple to fine-tune the interior temperature.

In short, there will be no problem regulating the temperature of the habs.

(Note: Health Tips on the Moon - Part 2 shows the Sports Hab, and the Sketchfab on the main page labelled Gallery Lunar Habitat shows the Gallery and the dome at the bottom of it - it is the 4th one, you have to scroll down a bit.)

The Pyramid Paradigm

noreply@blogger.com (Kim Holder) — Wed, 21 Sep 2016 17:56:00 +0000

Long, long ago, all of the very first nations on the face of the Earth made really big things. They made the very biggest things they could figure out how to. For a long time they raised huge stones over tombs or temples. Then they took to building a wide variety of pyramids. The one we simply know as the Great Pyramid remains the heaviest structure ever built, handily beating the Romanian Palace of the Parliament, which is the heaviest modern building and an interesting point of comparison.

The Romanian Parliament, known in Romania as Casa Poporului (the People's House) was built by the nation's soldiers, in a land at the time ruled by a brutal dictator. It took between 20,000 and 100,000 of them working under forced labor sometimes around the clock for 5 years, and the rest of Romania was deprived of basic needs in order to fund this. It is said that hundreds of workers, maybe as many as 3000, died during construction. The project stopped when the dictator and his wife were overthrown and executed in 1989. I remember the film shown on the news in Canada of the Ceausescus' dead bodies, a clip taken by the Romanian revolutionaries who wished to prove to their countrymen that they were really dead. Despite their hatred of everything the building represents, Romanians eventually decided that it only made sense to use Casa Poporului as the seat of government, the purpose for which it was built. So much was sacrificed to build it, and it is, in the end, well adapted to the task if one looks past its authoritarian feel.

The great Egyptian pyramids were not built under duress. Though this was believed for a long time, in reality unskilled workers labored as their customary duty to the king. They came to Giza for a season to satisfy this custom and received pay in loaves and beer. They may have been mostly volunteers. The many skilled workers who labored year-round lived well and had high social status. Egypt's pyramids genuinely were what Casa Poporului aped so tragically - national projects that forged a national identity. To this day most people recognize pictures of the Great pyramid and many travel from across the globe to see it. It isn't hard to imagine how proud the ancient Egyptians were of it, and how gladly they identified themselves with the culture responsible for it, and thus shed most of their loyalty to their tribes. And that was essential for the nation of Egypt to work. It minimized rivalry between the many small bands that existed along the Nile before they were unified, until people stopped saying they belonged to a certain tribe, and instead started saying they came from a certain village, in Egypt. Having a custom under which people from all the tribes came together to labor together on monumental religious projects was, therefore, the way the bonds were forged that made Egypt.

When one looks at all the many other giant constructions before the great pyramids of Egypt, and for some time after them, all over the world wherever nations were first forming, they were all religious. Many of them were tombs, but since ancient peoples universally believed in ghosts, essentially they were religious. That allowed tribal rivalries and conflicts to be set aside during labor to create them. Humans naturally regard spiritual matters as more important than that - even if in many cases it is only out of hope to be granted holy favor, or to avoid supernatural curses. At any rate if an attempt had been made to unify the same groups by getting them to build something together that served a political purpose, that would have provoked instant rebellion. The matter was neatly side-stepped by building temples and tombs for great spirits instead. And that led to a rather magical change in attitude - service to the holy would not be worthy unless it was fitting of the great power of the world's unseen forces. It was therefore critical that the monuments be things of wonder. They strived to their utmost to achieve this. This instinct was, in the end, exquisitely astute. For one, that meant it was necessary to figure out how to make detailed plans, communicate them, and then coordinate hundreds, and later thousands, of people in a very precise and highly orderly fashion. That ability was later used to build other highly complex things that were more immediately useful. What is more, their monumental efforts created the monuments that forged the identities of all the world's very first nations, which reduced the number of borders being fought over by a couple of orders of magnitude. This is known as the Neolithic Revolution.

The resources used to build those megaliths and pyramids were a much larger portion of those original nations' economies than any project in the modern world, with a very few exceptions. All of the exceptions have tones similar to that of Casa Poporului. For instance, the Palace of Versailles was possible at the peak of French power, helped by the income of its colonies, but also played an important part in the bankruptcy of the monarchy and the Revolution that followed. People have come to be very suspicious of grandiose projects. For instance, we invented the word 'grandiose'. We recognize them as a play for power on the part of an elite. They have lost all echoes of spirituality, now that there is nothing wondrous about building huge ornate things. Spiritual buildings are still often made on a larger-than-life scale, but that only goes so far. Any farther, and it becomes evident they are not there to render service to a community, but instead are there to demand service from a community. That just doesn't work any more.

Yet we are in a time of turbulent change. Once again the social systems that served us in the past seem worn out. Millennia ago when we'd covered the globe and become too sophisticated to continue fighting as one tribe against another, we created something new that gave us a new way to relate to each other. Our spirits rose to the occasion and thus we averted a future where burgeoning populations and advancing technologies caused us to soak the world in blood, as we fought tribe on tribe for ever scarcer resources. Instead we created nations, which enabled us to increase our resources so there was enough for all. Peace over large areas allowed the planting of crops over large areas, the storage of surplus in central grain silos, the processing into flour at central mills, the development of extensive irrigation systems. Soon we were off and running, specializing our labor ever more, trading over ever greater distances, figuring out how to keep track of all this commerce with symbolic marks. Sure, we also got organized slavery, standing armies, social classes, but it was still a lot better than what would have happened otherwise. The change we are in the midst of is no less significant. Once again we are in peril if we don't reorganize on a fundamental level.

There are striking parallels here to the Neolithic Revolution. Once again we are at risk principally because of how much more powerful we have become.

Once again war has ceased to be a sensible way to settle disputes, because there can be no real winners. Before the Neolithic Revolution thousands of ongoing disputes between tribes all over the planet were constantly draining us and solving nothing. Now the risk is that just one war can scar the whole planet if nuclear weapons become involved. Or smaller wars can be so destructive they destabilize whole regions for decades and cause ripple effects very far away. It has gotten to the point where there are wars conducted not by nations, but by multi-national groups scattered across a dozen countries.

Once again it has come to this because of our increasing wealth and technological sophistication. We have never been so wealthy, but our numbers and our wealth have strained ecosystems all over the planet and changed the climate. Our technology is changing balances of power in every organizational category we have - institutions, industries, cultures, economies, the whole world. Traditional forms are being undermined, new ones are emerging chaotically, and the void is sometimes being replaced by something dangerous.

Once again, the principal thing that prevents us from solving these problems is that we are splintered into groups that are too small. It took a series of wars of conquest to initiate the Neolithic Revolution. Well, on the time scales we are working with here we have already gone through two wars of unprecedented scope and cost in the recent past, the World Wars. The second one, especially, provoked an attempt to organize ourselves on an international level to avoid such conflicts in future and start solving the problems that affect the whole world. This was very valuable, but clearly has not gone nearly far enough. And it isn't a matter of putting more resources into the UN, or changing laws. We need something new.

Once again, we will not find that new thing until we forge the bonds necessary for it to emerge, by working together on something so grand it brings out the best in us and instills a sense of wonder. Once again, we must transfer our loyalty to something larger and we will not unless it meets that standard, and that is fitting. Once again, it has to be something we can see, something we can contemplate, a symbol around which everything else coalesces. We are still the people we were back then, when we demoted our loyalty to our tribe in favor of something larger. This is how we work.

There is only one possibility. It stares us in the face and we fear to make the commitment because it will be so hard, demand a level of commitment and coordination we have never managed before. Our ancestors surely felt the same way, but eventually it was clear there was no choice. They put their shoulders into it, and grew.

We have to settle the Moon. Mars is too far away to have the effect back home that is needed. A space station can't be built on the scale required without going to the Moon first. We have to go, and we have to go big. Only a project that is on the scale only possible if a large group of nations does it together will serve the purpose. It will only instill wonder at that scale. It will only forge bonds on that scale.

I am not even slightly joking about this. I believe this is of critical importance, and that we may not have much time before other events lead us into another conflict of extraordinary cost. We have managed to reorganize in some ways that will help, but it isn't enough. I believe the wonder people feel about space missions, and the inordinate eagerness of a small number of us to create these great works, is a sign of this instinct coming into play. In that case the instinct is only going to grow until it reaches the right critical mass. Will that happen before it is too late? The world has been surprisingly peaceful and ever wealthier for a long time now, it is easy to think there is no hurry here. On the other hand, nukes are being acquired by ever more unstable people, we have no idea what the near future of our climate is, and we have been performing a series of giant macro-economic experiments that show many signs of possible failure.

We need to make a broad call that touches the imagination of ordinary people and convinces them a big international Moon project would be exciting and transformational. If something awful happens and that idea hasn't already gotten purchase and begun to roll, that same instinct to take group action will move people to choose the dark twin of great construction projects: War.

Please help Moonwards create an exciting and realistic vision for a Moon colony. We need a strong team. There is much to do.

All the Reasons Why

noreply@blogger.com (Kim Holder) — Mon, 05 Sep 2016 22:13:00 +0000

Moonwards is a bit of a different approach to promoting space. It seems time to properly summarize that. I'm on The Space Show next Sunday, Sept. 11th, and i need to organize my thoughts. It hasn't seemed useful (up to now) to contrast it with various other projects out there, so this gap keeps reappearing where people wonder why it isn't done like x or y.

99% of the imagery of space that most people see is in fiction, there is a huge quantity of material. For most people, what we are really doing in space is pretty boring by comparison. Unless they have a background in the sciences that allows them to appreciate it, it just isn't going to hold their attention. However, the growing proportion of popular fiction that takes place in space is a signal of something important. Human cultures are increasingly transferring their broadest vision of our hopes and dreams to a space setting. If you want to reach people, and get them thinking about what the road to our greatest dreams needs to be, tapping that has huge potential.

So Moonwards is building a bridge between the vast energy placed in fictional visions and something that could actually be done. It seeks a keen balance between realism and fantasy that powerfully makes key points about who we are and what we should pursue. A city on the Moon can capture the imagination. Yes, you could fly by flapping wings, needing only your own strength. Yes, you could leap from the water like a dolphin. You could carry 10 people on your shoulders, jump to the roof of a house. You could run for miles and miles without exhaustion - you could just run wherever you go without it being a big deal. You could run everyplace with a friend on your shoulders, and switch occasionally between who is carrying who. The scale of what we could build there once we built up infrastructure would also be that much grander. Ladders into space, skyscrapers miles high, pits miles deep.

When you paint a picture like that, and say that isn't a fantasy, that is what it would really be like, that makes an impression. I could go on at great length on how that impression can have a ripple effect on how people see the value of things in general, and their willingness to work together to achieve the great things that can only be achieved together. But there are other things to cover...

There are several plans out there about businesses or colonies at a lunar pole, and yet Cernan's Promise is placed at the equator. The main defense for this is the building approach. Basalt is needed in order to build big quickly. Only with basalt can you make everything needed - the cables that contain the pressure of atmosphere, and the many different construction materials for arches, columns, floors, walls, and furnishings. Only by building large can you have long-term residents who don't go crazy but are actually happy. Selling residence is the core business of the colony in the initial phase, augmented by broadcasting that can also only be done successfully in a large, beautiful building. If you try to build large and beautiful with any other technique, it takes so much machinery to do that you might as well have used that mass to bring up the machinery to melt and process basalt. The machinery needed to create waterless concrete and build with it would weigh much more (and need rebar), the machinery to excavate and emplace regolith over inflatables would weigh about the same as the machinery needed to excavate and build with fused basalt and basalt cable. If you want something larger than an inflatable that can be rolled up and packed within a fairing, you also need equipment to stitch and weld seams that are reliably strong, and to maneuver large pieces of fabric without damaging them. Unless you reinforce the inflatable with elements strong enough to support the regolith overlay in the event of loss of atmosphere, you risk complete disaster if something rips the fabric - a fire, an explosion, a chemical spill, one person who completely loses it for 30 seconds. But if you put in that reinforcing structure, you might as well just have built out of basalt, in which case you could have built all your furnishings and internal structures in the bargain with the same machinery, and also more entire habitats.

Because it is at the equator, Cernan's Promise can't take advantage of the water and other chemicals frozen in the ground of the poles. We don't know how difficult it will be to mine the poles for water. It might be easy, but it might be very hard. I really doubt there will be a viable market for water as rocket fuel, so the money that would be spent setting up mining is better spent sending a payload of water to the equator, and methane to power a nuclear thermal shuttle. Because Moonwards looks purely at the potential of our technology, planning for nuclear ships is a logical step. That means fuel supplies can be stretched much further, especially once you add a cargo ship running on ion engines shuttling between lunar orbit and LEO. The nuclear shuttle just needs to go to orbit to unload the cargo ship. By the time the colony needs more water than can be accommodated in the payload budget it has with Earth, it will be capable of building most of the mass of the machinery and habs needed for water mining itself. Those can then be taken to the north pole for much less fuel than if everything had to be brought from Earth, and fewer Earth launches would be needed.

More about the transport solution is in the previous post. That post is also going to be updated in a few days with input from Sigvart Brendberg, who made some very salient points recently that really improve it. Like pointing out the nuclear shuttles should run on methane, and the cargo ship should be launched as the second mission, instead of a nuclear shuttle going all the way to LEO. I'd like to highlight again the importance of tethers. Tethers in lunar orbit makes movement of bulk cargo around the moon feasible, and also movement between the surface and lunar orbit. That is critical if the Moon is to become mostly free of shipments from Earth. If you can't get all the volatiles you need from the poles, you can get them by bringing carbonaceous asteroids to orbit. With just one polar tether you can get transport coverage of most of the Moon, so once you find the craters where meteors impacted with speeds low enough that remnants of them remain there, you can find metals, hydrocarbons, and nitrogen chemicals there, as well.

By accepting nuclear power into our lives, Moonwards also solves the energy problem of the long cold nights, which polar colonies handle by staying on peaks where there is sun 90% of the time. Nuclear generators will power the colony in the early days. Since everything is being made of solid basalt, and there are also a lot of boulders around at the site of Cernan's Promise, thermal mass will make temperature regulation way easier. Machinery outside will be protected from the cold on solid basalt platforms warmed by the sun during the day, tucked under reflective tarps that trap the heat. Later a hangar with a thick basalt floor and several layers of reflective insulation suspended tent-style over the whole space will keep temperatures quite even.

I think those are the things i wanted to cover... One last thing is that the influence a true colony would have on Earth, a colony with at least a thousand people, that is developing its own culture, is hard to overstate. Transmissions between the Moon and Earth would be literally a million times what that transmission power could send between Earth and Mars when they are farthest apart. Running a hundred 4K channels all the time would be no problem, with all the video calls and file transfers you could possibly want on top of that. Places that are entirely new encourage new ways of thought, and that tends to be very powerful. An example i think is relevant: American Revolution, 1776... French Revolution, 1789.

Transportation that Builds Momentum

noreply@blogger.com (Kim Holder) — Thu, 25 Aug 2016 22:29:00 +0000

There is no way around it. The different resources of the Moon are in different places, and they don't seem to be close together. Mapping of resources is really patchy, low-resolution, and incomplete, so maybe there is a sweet spot that helps with this we have only to discover. Probably not, though, and even if there is, if you are talking about serious development, you are going to need to go get things from far away sooner or later.

Building first at the equator simplifies some things but runs into this as soon as the water supply comes up. For all that it is much easier to build big quickly at Lalande Crater, it has advantages in trajectories to and from Earth, and has much more iron, potassium, phosphorus, thorium, and rare earth elements than the poles, all of its water has to be delivered. A base at the poles could get its water from permanently shadowed craters once the machinery to do so had been developed and built. That could prove difficult and expensive though - we don't know yet. If you set up an efficient supply route from Earth, supplying enough water doesn't get problematic until it is time to expand the colony from the initial crew of 30 to a population of hundreds. Even then, if you skipped putting in giant swimming pools it is conceivable you could simply add a few cargo runs to your schedule loaded with nothing but water from Earth and stay within your budget. However, a place on the Moon where people are supposed to live for the rest of their lives really ought to have giant swimming pools. So, the trick is how to bring kilotons of water to the colony for those residents. And just aside from that you will want to be able to move kilotons onto and off of the Moon anyhow, so this is really just the first, most obvious case of that need.

As always, in assessing the position that follows it is important to remember that Moonwards is about showing what could be done if limitations imposed by politics were removed and serious ongoing investment was made. Actually, i should write that up as a blurb that goes in the header or sidebar of this blog... So if you see that now in that spot, this is when that occurred to me.

Our planned route to industrial-scale cargo movement around the Moon and between it and space is first, building a shuttle with nuclear thermal engines and a cargo ship with ion engines. The shuttle would handle transport between lunar orbit and the colony, and the cargo ship would do the run between lunar orbit and low Earth orbit. Then once the initial complement of scouting and construction robots and equipment had been delivered, the next mission would set up a non-rotating tether in an equatorial orbit at an altitude of 5000 km. At first that tether, or skyhook, would only descend part way to the surface. As the shuttle and further cargo missions added mass to the tether anchor and the system was perfected, the skyhook would reach to 20 km above the surface. Finally, a polar skyhook is added and further tethers reaching to low Earth orbit. Let's look at this piece by piece.

Nuclear thermal engines would require little development to create working models, their performance is superior, they are robust and can be restarted with ease, and they are safe. Their nuclear fuel elements would not be put together and start generating high radiation until in lunar orbit, so if there was a launch accident dispersion of radiation would not happen. Once operational, shielding the engines enough to block their radiation from entering the interior of the shuttle is quite easy. The shuttle would run both on straight hydrogen, and on methane. On methane it could get a specific impulse of about 500 s, on hydrogen, about 900. Using methane would give superior thrust during take-off and landing. More importantly, shipping and storing methane is far easier than doing that with hydrogen. Possibly the total payload to the colony would be maximized by not using hydrogen at all. Or maybe if hydrogen was a small portion of the mass of the propellant, and large tanks could be used that allow use of high-pressure gaseous hydrogen instead of liquid hydrogen, it would be advantageous to use a mix.

The much larger cargo vessel could run on xenon. If the HiPEP ion engines NASA has worked on were fully developed, they could have a specific impulse of up to 9000 s. At that efficiency, and given that they have to use the slow spiral trajectory of low-thrust engines, they could deliver a ton of payload for every 115 kg of propellant.

The skyhooks take more technological development. Zylon is an existing material that is strong enough for the cables, but issues to do with maintenance on a cable of that length, and how best to make cars that travel up and down it come up. The cable can't get twisted too much, it needs to be able to take hits by micrometeorites (a big hit isn't too likely, i don't think, but it has to be engineered for), and it needs to be repairable. A loose tubular braid of a couple of dozen smaller cables sounds like a good idea. Maybe the climbing car could have sort of twin caterpillar tracks that press together from either side of the cable, meshing with it at many points to distribute the strain, something like that. At any rate, these seem like moderate hurdles to overcome, especially considering how awesome the thing you get in return is. It might take some time to get used to handling the undulations and oscillations of such a cable, but those are probably minor issues that maybe need to be compensated for a bit. I leave this for now to minds that are actually trained to study such questions. I'd just like to explain how very cool it would be.

If you have a mass in orbit around the Moon and a tether hanging down from it toward the surface, the rate the foot of the tether moves relative to the surface is determined by the orbital period of the center of mass of the whole structure. When that point is at 5000 km altitude, and the foot is at 20 km altitude, that rate is 223 m/s. In that situation, our nuclear shuttle from the surface could go meet the foot of that tether, be grappled by it, trade a payload pod on its cargo bed for one released by the foot, hang on until the orbit is back over the colony, let go, and land on a runway. The delta V it would need to do that would be a fraction of what it would need to ascend 5000 km to meet the cargo ship in orbit. (I don't know what fraction is plausible for that - i briefly took a stab at calculating it, but my math skills aren't there yet, so i have demurred for now.)

The tether anchor needs to have ion engines on it, enough to compensate for the downward drag of having the shuttle hanging on its foot, and the solar panels to power them. Unless the skyhook's anchor is many times the mass of the shuttles and payloads, the downward drag during loading at the foot would need to be compensated for quickly in order to avoid the foot dropping down so much that it smacks into the ground. At first the tether would need to stay much further from the surface in order to avoid this being an issue, and the shuttles would need to climb higher and faster to meet it. And so, each time they do, they might as well haul up a full load of rocks that can be taken by the climber back up to the anchor, where they would simply add to its mass. As the anchor gets heavier, the tether can be extended to reach closer to the surface. Once those rocks reach the anchor and the shuttle has let go, the center of mass rises to its usual spot, so the structure only loses the momentum needed to carry the shuttle while the exchange is being made. But since that takes a few days, between the payload from orbit descending 5000 km, the tradeoff being done, and the rocks ascending 5000 km, the upward rebound at the end of the process isn't relevant. Still, the amount of fuel used to do these maneuvers is reduced because the ion engines on the anchor do most of the work, and they are much more efficient than even nuclear thermal engines.

This system really takes off once a near-Earth asteroid is delivered to lunar orbit and integrated into the skyhook anchor mass. It really needs to be big though. I'm thinking the thing to model for the virtual colony would be one of about 5,000 metric tons, which is 10 times the size of what the Keck Report on asteroid retrieval was proposing. That isn't unreasonable if you have a heavy lift launcher and the next generation of ion engines at your disposal. The asteroid would arrive already equipped with ion engines and solar panels, thanks to the equipment installed to move it. A nice carbonaceous chondrite asteroid could be counted on to bear 500 tons of water bound up in its minerals. The processing facility to extract that could be installed on the asteroid surface, and it would send that down to the colony in exchange for loads of building materials. By the time that asteroid is in place, the colony would be producing those. In fact, those building materials would be used to create a space station on the asteroid. By that time, the colony would be capable of producing most of the things needed for that.

A polar skyhook would also be set up and get a near-Earth asteroid of its own. With that in place, a base at one of the poles can be done in style. The machinery and gear would be delivered from Cernan's Promise by shuttles that ride the tether, and a lot of it would have been fabricated there. So now you are talking about 1000 tons of water from the two asteroids, and a new stream of water from operations at the pole. It is going to take a while before the giant swimming pool is completely full. Once it is though, you can build another in a small fraction of the time, for a small fraction of the cost.

With reusable launchers, this architecture is definitely something a group of nations could move forward on quickly. Having a truly reusable launcher that greatly lowers the cost of the last and most difficult link in the chain, Earth to low Earth orbit, would be the key to ramping this transport system up into a genuine cargo system. Tethers between LEO and lunar orbit would amplify the capacity of the cargo run a great deal as well. The Trans Cislunar Railroad described in Hop David's blog would be the thing to add. If some of the mass being pumped up the tethers on the Moon were directed onwards to those tethers, it could be used to build very nice space stations at the anchor masses of each of them. That system would greatly reduce the transit time for cargo between the two worlds. I was greatly helped in creating this sketch of the skyhook system that will be built in Moonwards by Hop's posts on tethers..

Another thing that would be a real boon to this system being built quickly and having lots of muscle would be successful development of the Neumann drive, which the colony could then fuel with magnesium refined on the surface and sent up to the tether anchors and the cargo ships. One of the set of calculations i look forward to doing is of how having lots of magnesium-burning Neumann drives on the cargo ships and tether anchors would speed up the whole process. However it is still not clear that there won't be development problems with that drive, promising though it seems.

Transport is the secret to everything in space. Feeling comfortable that this is an efficient, effective, realistic architecture is critical to making the virtual lunar colony feel real. We think it is. Let us know what you think.

(Note: This post was edited a month after the original posting in order to reflect improvements Sigvart made.)

Health Tips on the Moon - Part 3

noreply@blogger.com (Kim Holder) — Thu, 18 Aug 2016 01:42:00 +0000

It is time to speak of radiation on the Moon. First i am going to explain it a bit, and point out things a lot of people don't know. One, we can only make decent guesses how much radiation there is on the Moon. Two, we don't know what it will do to people. Three, a bit of shielding makes it much worse, not better.

One - We have no direct measurements of radiation levels on the Moon's surface, and modeling that environment with software is extraordinarily complex. This paper based on modelling found galactic cosmic radiation (GCR) fluctuates between 0.38 Sv/yr at solar minimum and 0.11 Sv/yr during solar maximum. (The solar wind scatters GCR particles that enter the solar system, and when it is stronger less penetrate to the inner solar system.) The Curiosity rover measured 0.66 Sv/yr in deep space on its way to Mars, 0.23 Sv/yr on the Martian surface in 2013, when solar activity was about half way between its minimum and maximum. The Moon is different than Mars because it has no atmosphere, but taking all those figures, using an average of 0.25 Sv/yr overall is probably within, say, 50% of the truth.

Two - Again using a lot of modeling and statistics, the estimate is that 0.5 Sv/yr increases an astronaut's chances of cancer by about 3% to 5%. In order to not increase those chances beyond that amount, radiation dose for a whole career is not to exceed 1 to 4 Sv, depending largely on the age and gender of the astronaut. There isn't enough data to consider other possible health risks due to radiation exposure, and even the figures used are a guesstimate. Actual effects could be much less or much more, they could vary a lot from person to person, and other factors like diet and exercise could change these probabilities greatly.

Three - Alright, so if there was no shielding, the estimates we have say that radiation levels would be acceptable for 4 to as much as 16 years. The trouble is, as soon as you put material between a person and the sky, the radiation gets worse - a lot worse - before it starts getting better when the shielding is thick enough. This is because of shrapnel. Cosmic rays are particles, mostly protons, but also the nuclei of a variety of atoms, moving at large fractions of the speed of light. What happens when these particles pass through matter is very complicated. Basically, they pass right through matter until they happen to hit an atomic nucleus. When they do, they smash that nucleus to pieces. The bits smashed apart have enough energy to smash another nucleus once they happen to hit one, and that can happen again, and again, until the energy is dispersed enough that the cascade stops. Because matter is almost entirely empty space, it is sheerly a matter of chance how far through a material these collisions happen. But if the material shielding you isn't thick enough for these cascades to have stopped before they reach you, the shrapnel multiplies the radiation damage you are getting. A recent graph in this video shows the radiation dose peaking at 8 times what it is without shielding, and that peak happens when you have about a meter of loose regolith between you and the sky. The dose doesn't drop below what an unshielded person would get until 4 m of regolith is in the way.

Okay... that was a big preamble, but in order to think clearly about this stuff, you have to know these things. The habitats designed for Cernan's Promise have projected radiation levels well below even 0.05 Sv/yr, which is the maximum dose for radiation workers. If you were to spend a lot of your time in certain spots that get higher exposure, you would exceed that dose, but you'd have to do that for hours a day. So, a conservative approach has been taken. And yet people will be able to look up and see the sky directly, and in the dugout, enough sunlight will enter directly to have a leafy garden.

I cheated a little by indicating where the sky is in this model by making it sky blue, which is clearly wrong. It would be black and starry, but on many days, you would be able to see the Earth through those gaps, which, if you ask me, makes up for that completely. And there would really be that sense of soft sunlight. What this is, is a series of tall narrow arches, with glass in between. As this colony is on the equator, because the Moon isn't tilted like the Earth is, sunlight would come in all day, every day. It would be a bit indirect because there is a slight angle, but the arches are faced with aluminum foil on their vertical faces so still lots comes in. (Hopefully that aluminum would be mirror smooth, to give a funky infinite mirror reflection effect when you look up into the gap between the arches.) Those are planters behind the figures, and they would be full up with all different plants. (LEDs get them through the night, but that is a different post.)

Sigvart wrote a small program to estimate the radiation dose in this space. It generates random rays coming in, tracks the thickness of material each ray passes through, and compares that to the curve shown in the video linked above for radiation levels through different thicknesses of material. That shows that there at the bottom where the figures are the dose is about 0.015 Sv/yr, if you spent all your time there. A third of what radiation workers are permitted on Earth. So, even with variations due to different geometry in different spots, this garden space is super safe. We could space the beams more widely to get more light and save on material - but the heat that comes with it takes some management, so i have left it like this for now.

Below is the window at the west end of the hall connected to the dugout.

In this case, the grey bar you can see outside reflects in the sky above. The area that directly shows the sky is small, mostly what is visible is Lalande Crater. Again this setup is very conservative. Even the green figure would see little enough of the sky even if the bar wasn't there that it would be pretty safe to stand there for hours every day looking out. But, that bar reflects in the Earth, which i have created views of wherever possible. It has mirrors on it angled so it does so, always, but they haven't been created in the model yet. And also, there is a narrow case where even that amount of sky would be dangerous if that bar wasn't there.

When solar particle events occur, ionizing radiation skyrockets for up to a few days. A few hours in that kind of radiation could kill a person. In this structure, if you aren't in the dugout, you are safe. If it should be the unlucky case that the sun was just about to set when it decided to flare on you, it would shine through that window and anything those rays struck would get a serious dose of radiation. But, if that should happen in this design, that bar would be in the way.

Stuff in the dugout would get a dose if the sun is high when this happens, during most of the year. But there is no need to be in the dugout. The crew would be alerted of the imminent arrival of the ionizing particles by the surge in x-rays that precedes it. The arches and the glass between would stop virtually all the x-rays and a lot of the gamma rays that happen in bursts before such events. They would have a few hours to get the plants into the hall and anything else that might be damaged by the solar storm, then they would hunker down there until it passes.

So, we're good here. And we can see outside, for real. I'm telling you, this would be a nice place to live.

Health tips on the Moon - Part 2

noreply@blogger.com (Kim Holder) — Tue, 09 Aug 2016 18:18:00 +0000

Before i do anything else i am going to deliberately refer you away from this blog, to the wonderful Lunar Swimming entry on Randall Munroe's What If blog, and please note that i asked that question. Please return for further discussion of the proposition.

All done? Okay, hopefully you noticed the bit that points out 'The inertia of the water is the main source of drag when swimming, and inertia is a property of matter independent of gravity. The top speed of a submerged swimmer would be about the same on the Moon as here—about 2 meters/second'. So, if you can swim, you can load your muscles just as much as they are loaded when you swim on Earth, and swimming is one of the best forms of exercise there is. It develops all your main muscle groups while not straining your joints. The pressure of the water against you could also be useful for encouraging redistribution of fluids, if the low gravity isn't enough to keep the fluids in our body where they ought to be (which it might be, and if it isn't, the water pressure while swimming might not help - speculation here).

Let us come back in a bit to the much more intriguing fact you could leap out of the water like a dolphin, and the splashiness matter, and talk about how else so much water can be useful. And let us also come back to the point that water is heavy and it would take a lot of infrastructure to get the water for large swimming pools to the colony, and more infrastructure still to do the audacious things with them i am about to propose. That is all just a matter of how far along the development path of a colony something like this would make sense. Development timelines change a lot when people decide they want something to happen, thus the relevant thing is to talk about the neatest possibilities.

Water is excellent radiation protection, and it is transparent. The one-sixth gravity helps a lot in containing large masses of it. So, i propose putting a great big swimming pool right against great big windows, and making as much of the sides and bottom of the pool as possible out of transparent material like quartz, sapphire, or high-strength plastics. Really the only way to practically have large windows on the Moon is to put a few meters of water between you and the outside. 'Practical' is, of course, a relative term. I think it applies here because if you live in a place where going outside means hopping around awkwardly in a stiff space suit and still being stuck seeing everything through a glass pane and not being able touch anything, after a while i bet you aren't going to be very interested in being outside. But if you stay inside, even the considerable effort made so far to create direct or reflected views of the outside will still give you only a narrow vista that is necessarily set a number of meters away. People are going to ache for a panoramic vista that can serve some limited substitution for the great outdoors left behind on Earth. So, this is the option. Until you can cover over entire craters in glass-and-water transparent roofs, which will make all the difference and i wouldn't even recommend settling the Moon if that wasn't completely feasible given enough infrastructure.

I give you your deluxe compensation for life in a snazzy box.

The pool sketched in the image is, of course, quite large. 57 m long, 7.5 m wide, 7.3 m deep, for a total of over 3 metric kilotons of water. So, since personally i don't think there will ever be a good reason to mine water at the lunar poles for propellant on any significant scale, here is the good reason to mine that water. Hotels on Earth go to great lengths to provide guests with awesome pools, some of those even have large expanses of load-bearing transparent sections just because it looks cool. The justification here is essentially pretty similar.

As long as you stayed at least a meter or two from the windows, you could gaze out them to your heart's content with no concern about radiation. Because you would be in that large body of water, the cone where there is so little water that radiation is elevated would be so narrow that the resulting dose is safe. Other tricks have been employed in this cylinder too - it is covered with plenty of regolith, and is under an overhang wide enough that not a lot of sky is visible if, for instance, your head is above water and you are quite close to the windows. A lot of the ground is visible, and scattered ionizing radiation will reach you from there, but that dose should be less than the dose from skywards. (I am going to need to seek numbers for that.) It seems to me that lunar residents are best left to judge for themselves how much time to spend in observation spots that come with a dose of radiation, and i imagine they will manage that without trouble. 10 minutes with a breathtaking view is worth a minor radiation hit a healthy person can manage without trouble.

And if you hanker getting moving, leap like a dolphin!!! To get up to a good speed at a good angle for an impressive leap, you want a pool this deep, and this long. Let's review the figures for a fit swimmer with flippers - they could leap 2 m out of the water. Oh yeah! I'd be in that pool all the time. This is an environment where you could really tire yourself out with a good race without being painfully aware of how often you have to turn around because of the limited space. It is a place for epic splash fights because droplets would hang in the air 6 times as long. Once i detail the pool i'll add a shelf where triple-decker chicken fights can be conducted, a suitable variety of diving boards, and 3 levels of pool-side lounging area set against its glass walls. The diameter of the cylinder that houses it actually now seems too small. It can only fit a non-springy diving board a measly 4 m above the water and you'd have to watch you didn't jump too high and hit your head on the roof. Clearly this pool requires a spring board at least 15 m above the water, and one would need to expect that jumping off it would launch you another 4 m higher. The architecture will need to be reconsidered...

In sum, exercise on the Moon that would genuinely load your body just like on Earth is entirely possible and would be super super fun. This i think is enough for us to not concern ourselves about muscle and bone wasting as long as people are willing to swim several times a week, which really doesn't seem like it will be a hard sell. There are other possibilities of course, which we can explore once detailed large models of the Gallery are done, like the simple but effective option of having no stairs anywhere and simply jumping between floors. And further out still, with a covered crater model, we can talk about artificial bat wings that allow you to actually fly. Yes, i'm serious.

Oh, i almost forgot, large amounts of water are also excellent heat sinks, greatly reducing the demands of thermal control. Yeah, that's kind of boring, isn't it... forget i mentioned it...

Health tips on the Moon - Part 1

noreply@blogger.com (Kim Holder) — Mon, 01 Aug 2016 22:34:00 +0000

I've been mulling how to address effective exercise on the Moon to address a host of health problems that come with low gravity. The main issues are loss of muscle and bone mass, and problems associated with redistribution of fluids, in particular how this can degrade eyesight. Also with the first habitat model coming along, i took a more critical look at its radiation protection and beefed it up.

As with many things, the exercise problem gets a lot easier if you have plenty of space to work with. That is why the first virtual moon colony being made is something pretty developed, to really assess the potential. Two things are being put in for exercise that hopefully could make a big difference. One is a human-powered centrifuge, a variation on the kind used to test human tolerance to high g forces. One the German space agency has is shown below:

You go in the box then it spins real fast

In the low gravity of the Moon, two or three people could slowly spin up something much larger until the effect was like a full gravity pressing people against the outer wall of a connected wheel, like old-fashioned Rotor amusement park rides. As evidence it really doesn't take that much power to revolve such a structure fast enough, I recall two older boys once had some fun spinning a roundabout, which is similar, so fast that i was no longer strong enough to hold on and went flying off, and i was not the only squealing kid on the ride begging them to stop. Ah, childhood... This is how long-term memories are formed...

Fun ride and torture device

So, it seems reasonable that in lunar conditions something that works on the same principle could be spun to the equivalent of one g and kept there by a few people. It would be good aerobic exercise for those keeping it going, time in one g for those who are on it, and it doesn't need any motors or a power supply so it isn't nearly as hard to build. In fact most of the structure could be made on-site. Everybody wins.

The people in the middle spin the wheel

Just a schematic. My 3d model skills are still immature...

(The spoke support system probably isn't adequate, but this is just a sketch right now.) Notice the 2-level central stand where up to 12 people could cooperate in keeping the wheel spun up, by first leaning against one of those red handles and pushing on it while trotting around the green platform, and then standing around the platform perimeter and hauling on the handles as they pass by. To be useful therapy for the people on the wheel, the speed for the equivalent of 1 gravity probably needs to be maintained for at least, say, a half hour, daily or a few times a week. Typically the human body keeps itself ready for the heaviest loading that is regularly experienced, so it is reasonable to suppose that such a level of exercise would keep lunar residents in decent shape. Crew on the ISS have to exercise much more than that, but they aren't able to do so in artificial gravity. The hope is that would make the key difference. As it is a group activity where everyone benefits, and would likely be sort of fun, it doesn't seem like it would be a problem to arrange for everyone to take turns, sometimes pushing the wheel, and sometimes riding on it. Turning the wheel would provide good aerobic exercise, working out on the wheel would be the anaerobic, strengthening component of their exercise program.

To be really effective, those on the wheel would need to do exercises while under that force, stuff that loads there bones and muscles well. Squats, push-ups, sit-ups, chin-ups, lunges, stuff like that. Just being on the wheel though would also be helpful. The crew on the International Space Station have some difficulties because there is no gravity keeping fluids properly distributed in their bodies, and so it collects in their upper bodies and especially in their heads. Pressure on their eyeballs due to that is the leading explanation for the vision problems they often have. Their sinuses also often get clogged. Being on the wheel would provide relief from that. The wheel has a wide enough radius to limit the dizziness people feel on such structures when they move their heads around - in this model it is 12 m. Spending an hour or more on it shouldn't cause nausea, though it might take people a bit to adapt to the sensations.

It isn't until we contemplate a space large enough for such an innovation, with the infrastructure in place to create it right there on the Moon so the expense isn't exorbitant, that we can really get our juices flowing and imagine a future colony in detail. This is hopefully a good example of that process. In the next few days i'll post about another very useful exercise option - swimming pools. That implies a lot of infrastructure too, more than this does even. But that is the goal, right? The thing is to outline the path leading there better and better.

Getting in Virtual Shape

noreply@blogger.com (Kim Holder) — Wed, 27 Jul 2016 17:51:00 +0000

This may not shock anybody, but building an entire virtual Moon colony is a really big job with many challenges. Trying to become more methodical and organized about it has led to a lull in visible output right now. It has also made the stack of tasks on my desktop look that much more daunting. For now. I hear that once a project is properly organized, things go much more smoothly. That would be really nice.

The Moonwards.com website was registered a year ago this week. I had been playing with the idea for a few months before that, and was encouraged to actually try it by people i met at the International Space Development Conference in Toronto in May of 2015. My idea of how that would go was really different at the time. Maybe it is typical when someone has an idea they find really exciting that they expect other people to find it equally exciting and hop on board just because one tells them about it. Now i realize that the rich, complex landscape of Moonwards in my head is only visible to me, and although many people find it interesting, they need much better reasons to devote their time to it than my enthusiasm and a small website. Turns out i actually have to figure out how to do this myself, and create the basic framework of it mostly on my own. Then it will draw people in and the actual doing of it will be shared among a group.

Now, i have actually received a good deal of help considering how preliminary the whole thing is. It very much encourages me to plug on, and has often made me smile. The last few weeks though have been mostly about looking at the 3d models i have built over the last 6 months, and pondering how poorly made they are, and dealing with rebuilding them somewhat professionally.

Can you find the 17 model issues in this picture? Well, i was trying, okay?

Turns out that when people who know 3d modelling toy with volunteering on a project, finding a bunch of rickety problematic models quickly curbs their enthusiasm. Hm. And going to the project's GitHub page and finding it is is mostly unstructured and has lots of obsolete files doesn't help. And while the whiteboard is very helpful to me and a great creative tool, most people want neatly laid out documentation so they can see a roadmap and understand exactly what needs doing and how it all fits together. But in order to do that, i have to stop dead in making things, and spend weeks just on that. Which i have resisted doing because i am super-fidgety to get a rough draft done, and that still seems more important to me. It's like needing to have a prototype done before setting up a production line. I'd still really like more help on the prototype though. Just please excuse the mess...

The solar furnace shown on the website is now obsolete and will be deleted in favor of a Schubert dust roaster. I was able to briefly talk to Peter Schubert about it at a conference and he seemed happy to have it on the site and will hopefully give me some guidance on it. But i haven't even started that because volunteers came in to work on the models and i tried to get things in shape for them. This is how i know that looked at through their eyes this thing is sort of a mess. Now the dugout and hall habitat models have been greatly improved, and i have learned a lot that will make future work faster and smoother. But i am still doing all the modelling on my own... I think i will take a break from fixing to mock up the dust roaster. Doing stuff like that is so much more satisfying. The rest is a bunch of incomplete models and various important models are missing. As for the homepage, I'm just going to take down the entire set of mission outlines that start half-way down, as they no longer apply and and were just meant as a sketch anyhow.

This remains a very difficult thing to do and it has yet to reach its first important goal of being one complete first draft. I hope that plateau provides the sense of security and momentum i am anticipating it will. If the whole thing didn't still strike me as a really great and important thing, i might set it aside. But it is important. If it doesn't flower into a highly popular and inspirational domain, at least it will hopefully be useful to the people who come after and do it right. Because it has to be done.

Walking Rovers on the Moon

noreply@blogger.com (Kim Holder) — Sat, 23 Jul 2016 20:31:00 +0000

Moon dust is super nasty. It is composed of particles of shrapnel, essentially, created during meteor strikes. The only bits that aren't all sharp edges are the blobs of glass from the portion that was thrown up as lava. You want to stay away from it as much as possible.

And when exploring a new world, you need to be able to handle all terrain, from steep crater walls of loose material, to fields of boulders, to deep crevices, to ponds of deep fine dust.

Also your vehicle has to do everything. It will have arms so it can do all the manual labor needed to build, manufacture, repair, prospect... whatever comes up, most of which won't be very predictable.

So the rovers for Cernan's Promise will take the ATHLETE rover model one step further. They chuck the wheels altogether and walk around, and some of the legs also can be arms. (I can't help but think that is the eventual idea for ATHLETE too.)

I rather like this video for getting across what i mean :)

The spider-bot that wants to be a rover

My thought is to reduce that concept to 6 legs, put mechanisms on two of them so that the bottom joint folds out of the way and hands are deployed for doing any kind of work.

The Space Show on Conquering the World

noreply@blogger.com (Kim Holder) — Sat, 23 Jul 2016 19:10:00 +0000

(Note: the following is one of various posts that were copied here from the Moonwards.com forum. It was originally posted there on June 6th, 2016.)

Here is a link to Friday's episode of The Space Show, where i talked about how the Moon could conquer Earth, and in general about how military acts in space can be extremely effective and hard to prevent.

It is a dark theme i talk about in order to propose a bright future. I believe that it would be by far the healthiest thing for the world to undertake our first extensive venture in space together, in a manner that is as inclusive as possible. This is the only way we can develop the cooperation and trust needed to keep space safe at the same time we create the possibility for it to become very dangerous. No system of laws, treaties, or regulations are going to be enough on their own. They will only work if we build a sense that we have a common interest world-wide in peace, and that can only happen if we feel we've done it together and we are all on the same team.

The timeline for Cernan's Promise will be based on that approach. I have been focused over the last 8 weeks on building rather complicated models (that i am in fact unsure how to display well on the website, they are that large), preparing for, attending, and doing follow-up emails for the ISDC in Puerto Rico, and getting used to being the new junior moderator on space.stackexchange. I have added some content to the site over the last week and hope to add much more in the next two or three. One of those bits of content is the Residency Program.

It has been outlined in the Mission Timelines already (which are screaming for an update, but hey, one does what one can). Basically, any nation can send an astronaut for life to Cernan's Promise for $100 million, and you need at least 200 such astronauts to provide sufficient income for development. There is an overt effort to get astronauts from as many countries as possible as part of this effort, and there are later rounds done on the same model that add more residency spots at increasingly cheaper prices. Once the settlement has a few thousand residents and the price for further spots has decreased to a level a significant percentage of Earth's population could afford, the market is opened to all.

To get across the urgency of doing whatever the first big thing we do in space is, as a world, together, making people realize that we could pay a grave price indeed down the road if we don't is absolutely necessary. So, i've started going on about it whenever the opportunity arises.

Hybrid Ice Shuttles

noreply@blogger.com (Kim Holder) — Sat, 23 Jul 2016 19:10:00 +0000

(Note: the following is one of various posts that were copied here from the Moonwards.com forum for the sake of preserving the early days of the project. It was originally posted there on April 22nd, 2016.)

A nuclear shuttle for transportation of ice from the pole to an equatorial base is limited by the thrust of its engine. That mass must accommodate the mass of the engine and all the other dry mass, and the propellant. What is left in the mass budget then is the payload. Note that fuel required for the return trip must be subtracted as well.

A reasonable delta-v budget for a one-way trip (including some gravity losses) is 3200 m/s.
For all my examples, I am going to use a hypothetical but realistic nuclear engine, at 2500kg, 100kN and an Isp of 950s

Using hydrogen:

We can calculate the required mass ratio:

Also, using a thrust to weight ratio of 2, the launch mass of the shuttle can 30,800 kg. (Scale as desired by adding more engines).
From the mass ratio, we get that 21,800kg of that can be used for the dry mass, payload and return trip fuel.

Using water:

First, why use water? After all, the Isp of water is only 45% of hydrogen. But, even though the mass ratio gets a lot worse, water allows us to get more thrust from the same engine. In a NTR, thrust is simply inversely proportional to the Isp.

So the same configuration with a T/W ratio of 2 allows us to increase the launch mass to 70,800kg. The mass ratio is 2.2, but that still gives us 32200kg for dry mass, etc. Absolutely an improvement.

But we can do better!

The extra thrust we get from the water is only required for the first part of the burn. After the shuttle has depleted some of its propellant, it is light enough that if you then switch to hydrogen, the T/W ratio is still good. (Also note that an high T/W ratio is not that important when you have gained a significant fraction of orbital velocity, making it even more favorable to switch propellant mid-burn.)

If, for instance, we use water for the first km/s of the ascent burn, and for the last 200 m/s of the landing burn, and hydrogen for the remaining 2km/s mid-flight. That results isn 37,300kg for the dry mass etc.

Thrust when needed, efficiency when possible.

My reply:

This is great, Sigvart, you have started my day off quite well for me. And you have taught me an essential new emoticon :[)

That idea i talked to you about the other day, of moving the colony to Aristillus, is one i really didn't want to take on, at least not right now. This issue of transport of material between the pole and the base was what had driven me to consider it. Aristillus is at 33 degrees N latitude, meaning a one way hop would take about 10% less fuel than a trip to Lalande on the equator. As a double sub-orbital hop to get to Lalande and then fly back takes so much fuel, you and Russell had warned me very little space would be left for payload. But water (and carbon chemicals, and ammonia, and the rest) is so darned useful. Even though i think setting up a fuel depot is a low priority, i keep thinking of amazing things to do with water. Lots and lots of water. And those other things.

There are two things i think will make the colony flourish, especially once people are there. If you do it well, broadcasting can bring in 2 or 3 billion dollars a year. And you sell permanent residence in the colony for $100 million a pop. I see residence sales working in the early days mostly because it should be an international sponsorship process. You announce to the world that any nation can send permanent residents of their choosing for that price, and you focus on assembling an initial population that is as representative as possible. Those residents are then representatives of their countries, like Olympic athletes, like astronauts are today. Lots of countries would be attracted to the prestige of that - years and years of national pride and inspiration for one relatively low price, all things considered. And you'd get an almost ideal initial population as well. The best and brightest. The diplomats, the figureheads of a way of life, a way of seeing life and our place in the universe.

Yeah - so, water. For those things above to work, they must come to live in a beautiful place, a place just about anyone would be happy to live. People's impression of how worthwhile it is to live in space, how rewarding the experience could be, will be based on what they see in these broadcasts and the feeling they pick up from those residents. There are so many cool things you can do with water to make the colony more inviting, but you need a lot of it. There is, of course, the classic What If? lunar swimming pool scenario. There are water walls and water domes - 5 m of water is pretty good radiation shielding. There are natural ponds that both provide a sense of nature and do some of the work of recycling waste water.

To do those things on a proper scale requires several thousand tons of water. Some of it will therefore wait for the installation of coil guns at both the equator and the pole. Because really, you can't go too far with this idea. Lakes. A lunar lake, if you are putting in an actual town, you've gotta have one. A dome over a whole crater - good ol' Teacup Crater gets that treatment first. That will take 350,000 tons of water. After that you can stand below that dome and see the sky all around, and sort of feel like you are outside, unencumbered by a space suit, for the first time on another planet.

Oh - Aristillus. It is also a KREEP hotspot. Perhaps it can get the second full colony, but i think we are too far along to move the colony again, and actually, i think there is a decent argument against it. The likelihood of an ilmenite deposit is much higher at Lalande, based on Clemintine data of TiO2 on the surface. Concentration of TiO2 is much higher at Lalande than at Aristillus. ilmenite gets water and iron when reacted with hydrogen. Aristillus also looks a lot older and doesn't have the wonderfully clean walls that Lalande has, that look so very much like the digging depth to get to bedrock isn't much. And the equator has a big advantage if you start doing stuff with tethers, whether you go through EML1 or make a lunavator. So Lalande it is. Which is also nice because i've become quite fond of Lalande after looking at it so much.

Things are shaping up nicely :)