Lunar Pioneer

Brightest impact recorded by NASA lunar monitoring program, March 17

noreply@blogger.com (Joel Raupe) — Fri, 17 May 2013 12:57:00 +0000

Impact with kinetic energy equivalent to 5 tons of TNT, March 17, 2013. Still from NASA ScienceCast released May 17. The event was the brightest of recorded over eight year span of NASA lunar impact monitoring program. Video still shows the nearside's earthshine-lit western hemisphere at the moment of impact, in the southern tier of Mare Imbrium, north by northwest of Copernicus [NASA/Science].

Dr. Tony Phillips
Science@NASA

For the past 8 years, NASA astronomers have been monitoring the Moon for signs of explosions caused by meteoroids hitting the lunar surface. "Lunar meteor showers" have turned out to be more common than anyone expected, with hundreds of detectable impacts occurring every year.

They've just seen the biggest explosion in the history of the program.

"On March 17, 2013, an object about the size of a small boulder hit the lunar surface in Mare Imbrium," says Bill Cooke of NASA's Meteoroid Environment Office. "It exploded in a flash nearly 10 times as bright as anything we've ever seen before."

Anyone looking at the Moon at the moment of impact could have seen the explosion--no telescope required. For about one second, the impact site was glowing like a 4th magnitude star.

Ron Suggs, an analyst at the Marshall Space Flight Center, was the first to notice the impact in a digital video recorded by one of the monitoring program's 14-inch telescopes. "It jumped right out at me, it was so bright," he recalls.

The 40 kg meteoroid measuring 0.3 to 0.4 meters wide hit the Moon traveling 56,000 mph. The resulting explosion1 packed as much punch as 5 tons of TNT.

NASA's lunar monitoring program has detected hundreds of meteoroid impacts over the eight year formal history of the program. The brightest, detected March 17, in Mare Imbrium, is marked by the red square [NASA/Science].

An impact on the trailing eastern limb of the Moon monitored January 8, 2008.

Cooke believes the lunar impact might have been part of a much larger event.

"On the night of March 17, NASA and University of Western Ontario all-sky cameras picked up an unusual number of deep-penetrating meteors right here on Earth," he says. "These fireballs were traveling along nearly identical orbits between Earth and the asteroid belt."

This means Earth and the Moon were pelted by meteoroids at about the same time.

“My working hypothesis is that the two events are related, and that this constitutes a short duration cluster of material encountered by the Earth-Moon system," says Cooke.

One of the goals of the lunar monitoring program is to identify new streams of space debris that pose a potential threat to the Earth-Moon system. The March 17th event seems to be a good candidate.

Controllers of NASA's Lunar Reconnaissance Orbiter have been notified of the strike. The crater could be as wide as 20 meters, which would make it an easy target for LRO the next time the spacecraft passes over the impact site. Comparing the size of the crater to the brightness of the flash would give researchers a valuable "ground truth" measurement to validate lunar impact models.

Unlike Earth, which has an atmosphere to protect it, the Moon is airless and exposed. "Lunar meteors" crash into the ground with fair frequency. Since the monitoring program began in 2005, NASA’s lunar impact team has detected more than 300 strikes, most orders of magnitude fainter than the March 17th event. Statistically speaking, more than half of all lunar meteors come from known meteoroid streams such as the Perseids and Leonids. The rest are sporadic meteors--random bits of comet and asteroid debris of unknown parentage.

U.S. Space Exploration Policy eventually calls for extended astronaut stays on the lunar surface. Identifying the sources of lunar meteors and measuring their impact rates gives future lunar explorers an idea of what to expect. Is it safe to go on a moonwalk, or not? The middle of March might be a good time to stay inside.

"We'll be keeping an eye out for signs of a repeat performance next year when the Earth-Moon system passes through the same region of space," says Cooke. “Meanwhile, our analysis of the March 17th event continues.”

A few related posts:
LROC team identifies a new lunar crater (July 28, 2010)
Lunar meteor impact observations and the flux of kilogram-sized meteoroids (July 25, 2010)
The Lunar Geminids (December 10, 2009)
Impact Gap in Moon's Southern Highlands? (May 22, 2008)

Dynamic Textures in the Farside Highland Terrain

noreply@blogger.com (Joel Raupe) — Thu, 16 May 2013 21:41:00 +0000

Northeastern portion of unnamed crater ejecta, above 77°N latitude, in the farside north. LROC Narrow Angle Camera (NAC) M138600267R, LRO orbit 5559, September 8, 2010; sunlight angle of incidence 80.3° over a field of view 1080 meters across, resolution 1.08 meters per pixel, from 51.96 km. Image center 77.086°N, 200.336°E, incidence angle is 80.3° [NASA/GSFC/Arizona State University].

Hiroyuki Sato
LROC News System

This far side high latitude (just above 77°N) fresh crater (roughly 1.1 kilometers in diameter) presents striking linear patterns in its ejecta.

Due to the high latitudes, the incidence angle is always very high in this area (including in this image), which enhances subtle topographic features.

The ejecta source crater is toward bottom left (outside the image field of view), thus the ejecta landed with the velocity component in upper right (northeast) direction, consistent with linear stripes dominating this whole area of this Featured Image.

LROC Wide Angle Camera (WAC) observation shows the whole crater of interest, at the center of this 46.2 km-wide field of view captured at 79.7 meters per pixel. North a smaller fresh crater almost immediately to the south-southeast. Both these crater's fresh, bright and optically immature ejecta fields are visible in the HDTV stills from Japan's SELENE-1 orbiter Kaguya, below. LROC WAC M173944659C (643 nm), spacecraft orbit 10768, October 22, 2011 [NASA/GSFC/Arizona State University].

Context for the LROC NAC frame outlined in this crop from LROC WAC monochrome mosaic (100 meters per pixel) of the unnamed crater and surrounding vicinity, centered near 77.46°N, 200.83°E, image width is about 142 km. NAC footprint (blue box) and the location of today's Featured Image (white arrow) are indicated here [NASA/GSFC/Arizona State University].

Interestingly, the lower left (closest to the rim) and upper left corners of this image show a craggy, rough surface, while the right portion shows only the striped pattern. What causes such texture differences within the same ejecta blanket?

Demonstration of just how far north the crater of interest resides in this three-HDTV frame animation, showing an Earthrise over Plaskett crater in the Moon's far north as captured from Japan's lunar orbiter SELENE-1 ('Kaguya') in 2007. The crater later photographed from overhead from LRO is designated with an arrow in the final frame. A large reproduction of the final still can be viewed HERE [JAXA/NHK/SELENE].

One possibility is the impact melt content was enriched near the rim, increasing the cohesion among the rock fragments and decelerating the flow inducing multiple pressure ridges perpendicular to the flow direction. Perhaps variations in roughness of the pre-existing surface controlled the final look of the ejecta. What else?

Explore this fascinating ejecta morphology in full NAC frame (HERE), and find your own hypothesis and answers!

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Action Shot
Polka-dot Ejecta
Smooth Ejecta
In the Wake of Giordano Bruno
Scours and Ejecta Near Jules Verne Y
Lassell D Ejecta
Swept Surface
Ejecta Patterns

Small Pond in Fecunditatis

noreply@blogger.com (Joel Raupe) — Wed, 15 May 2013 21:31:00 +0000

Unnamed crater floor at the western edge of Mare Fecunditatis. LROC Narrow Angle Camera (NAC) M167919653R, LRO orbit 9880, August 14, 2011. Image center 6.422°S, 43.747°E, field of view 561 meters across, angle of incidence 42.28° at 56 cm per pixel resolution, from 26.95 km [NASA/GSFC/Arizona State University].

Hiroyuki Sato
LROC News System

Today's Featured Image highlights an unnamed small crater (roughly 600 meters in diameter) observed at western edge of Mare Fecunditatis.

As seen in images further down, the higher reflectance (optically) immature ejecta blanket of this crater suggests a young age relative to the adjacent craters.

The crater walls are mostly covered by collapsed materials but the bottom still shows the original floor. The most remarkable feature is the central pit filled with impact melt (~100 m in diameter) with wrinkles on its surface. What are wrinkles telling us?

Full 56 cm per pixel resolution view of the crater of interest in Mare Fecunditatis, from LROC NAC M167919653R [NASA/GSFC/Arizona State University].

Most of the ejecta blanket from a mosaic of both the left and right frames (M167919653LR) of the LROC NAC observation, a field of view 2.06 km-wide [NASA/GSFC/Arizona State University].

Probably this is a quenched surface of melt flows that coalesced from multiple directions, and each wrinkle corresponds to the contact boundary of different flow units. The mushroom shape extending from south toward the center could have been the last flow unit that squeezed through the earlier arriving melt. Post surface cracking may also contribute resulting in these complicated patterns. Impact melts exhibit large variety in their final shapes due to their complicated rheology changing with time. It must be interesting to see how different or similar they are to the volcanic surfaces of active Hawaiian volcanoes.

LROC WAC monochrome mosaic (100 m/pix) of the western portion of Mare Fecunditatis, centered at 6.67°S, 43.73°E shows the NAC footprint (blue box) and location of the area shown at high resolution in the Featured Image above (yellow arrow) [NASA/GSFC/Arizona State University].

Explore the wrinkles on this tiny melt pond in full NAC frame for yourself, HERE.

Related Posts:
Channels And Fractures
Farside impact!
Crater in 3D!
Young Highlands Crater
Rippled Pond
Messy Crater

Swarm of Secondaries on the floor of Crüger

noreply@blogger.com (Joel Raupe) — Tue, 14 May 2013 19:44:00 +0000

Western portion of Crüger crater floor. LROC Narrow Angle Camera (NAC) mosaic (M1108725909R and M1108725909L), LRO orbit 15669, November 28, 2012, centered near 16.759°S, 292.627°E, field of view 1670 meters, sunlight from the west, angle of incidence 72.32° at 1.67 meters per pixel resolution, from 79.83 km [NASA/GSFC/Arizona State University].

Hiroyuki Sato

LROC News Center

Crüger is a 45 km diameter crater located between Oceanus Procellarum and Orientale basin. The floor is completely covered in basaltic lava deposits, and is very flat. The western portion of the floor shows slightly high reflectance spots with clustered craters and disturbed surfaces, likely a field of secondary craters.

A unique feature of this grouping is the sharp topographic relief delimiting its southern boundary.

The upper half of the opening image, the relatively disturbed and hummocky part, corresponds to the cluster area. Note that the sunlight is from the right side, and the cluster area is topographically lower than the southern relatively smooth area along the delimiting boundary.

LROC NAC context mosaic M1108725909L R showing the Crüger crater floor, a 7.3 km-wide field of view, image centered on 16.736°S, 292.645°E [NASA/GSFC/Arizona State University].

Roughly 20 km-wide field of view from a 62 meter per pixel resolution LROC Wide Angle Camera (WAC) frame shows the 'chevron' of encapsulated secondary craters on the west central floor of 45 km Crüger. LROC WAC observation M129729786C (689 nm), spacecraft orbit 4251, May 28, 2010; angle of incidence 62.36° from 44.57 km [NASA/GSFC/Arizona State University].

WAC monochrome mosaic (100 m/pix) of Crüger crater and surrounding area. Image center is 17.15°S, 293.05°E. Two NAC footprints (blue boxes) and the location of today's Featured Image are indicated here [NASA/GSFC/Arizona State University].

As seen in the NAC context view, the southern end of this secondary cluster is surrounded by this sharp boundary. Likely a densely packed group of ejecta landed with a low angle, resulting in this unique deposition pattern.

Explore this unique secondary crater cluster patterns in full NAC frame yourself, HERE.

Related Posts:
Cluster of farside secondary craters
Stream of Secondary Craters
Chain of secondary craters in Mare Orientale
Regolith on Basalt
Clusters
Tres Amicis
Crater Chain near Rima T Mayer

Earth-Moon: A Watery "Double-Planet"

noreply@blogger.com (Joel Raupe) — Tue, 14 May 2013 16:34:00 +0000

A watery double-planet: Luna and Terra. Viewed along a narrow line-of-sight from the Jovian probe Galileo, December 16, 1992. Having re-encountered Earth and Moon eight days earlier, for additional gravimetric acceleration toward its mission at Jupiter, Galileo was 6.2 million kilometers away [NASA/JPL].

Paul D. Spudis
The Once and Future Moon
Smithsonian Air & Space

Science Magazine recently published a paper that reports that minute quantities of water contained in lunar volcanic glass appear to be identical in isotopic composition to terrestrial water. According to subsequent press reports, this finding revolutionizes our understanding of the origin of Earth and Moon. But does it?

Water is a simple molecule, made up of two hydrogen atoms and one oxygen atom. However, these atoms are not all made the same – they always contain the same number of protons and electrons but the number of neutrons they contain varies. In particular, some naturally occurring hydrogen contains an extra neutron and hence has twice the mass of normal hydrogen. This “heavy hydrogen” (called deuterium, for its atomic weight of two) is much less abundant than its lighter version. Planetary scientists use the amounts of deuterium, relative to normal hydrogen, as a measure of the provenance of the material, i.e., where it formed relative to the Sun.

Ultimately, substances that have identical deuterium/hydrogen ratios are presumed to have come from the same source. We have reason to believe this ratio increases systematically outward from the Sun, depending upon where in the early “solar nebula” the material condensed and its subsequent geological processing. Oxygen (the other element in water) also has an isotopic variation; normal oxygen has 16 protons in its nucleus, but the other isotopes of oxygen can have an additional neutron or two. As with hydrogen, the variation in the ratios of normal to “heavy” oxygen is thought to be indicative of where the material comes from.

Of course nothing is ever quite so simple and straightforward. Subsequent processing, such as interaction with cosmic rays, can sometimes alter the composition of samples but if these effects can be accounted for and eliminated, isotopic composition can be used as a tool to map the ultimate sources of Solar System debris. This has been done with many different elements and compounds, but oxygen and hydrogen are very volatile and thus, sensitive indicators of the thermal environment in which they formed.

When the isotopic composition of an element like oxygen is plotted for the various groups of Solar System materials – meteorites, lunar, martian and terrestrial samples – they all form distinct groups, indicating that the source reservoirs of these materials formed in different locations of the nebula. The most primitive type of meteorite – carbonaceous chondrite – appears to have formed at the farthest distance from the Sun. These rocks are thought to have originated within once icy bodies, the cores of objects known as comets. Comets form in the outer Solar System where low temperature substances are abundant and are occasionally perturbed by gravity to enter the inner Solar System, i.e., inside the orbit of Jupiter. Once there, they are heated by the Sun and their most volatile components are sublimed away; after multiple passes through the inner planet zone, only a small fraction of this primitive material remains.

Called the Genesis Rock, Apollo 15 sample of unbrecciated anorthosite was thought to be a piece of the Moon's primordial crust. In a paper published online, February 17, traces of water were reported found by a University of Michigan researcher and colleagues [NASA/JSC].

The new findings indicate that the isotopic composition of the hydrogen in water in the mantle (deep interior) of the Moon is nearly identical to that in the water of Earth’s mantle, and both appear to have come from carbonaceous chondrite (most primitive) meteorites. When compared to a variety of data from other Solar System objects (including the giant planets, icy outer planet satellites and meteorite groups) the Earth-Moon system is compositionally distinct and identical, indicating that, whatever our origins, the description of Earth and Moon as a double-planet is even more appropriate than we had thought.

As early as late 1969, preliminary analysis of the first lunar sample returned to Earth were announced to be totally devoid of water, and the Moon, as a whole, therefore completely dry. Forty years later, superior equipment allowed finer measurements of trapped gasses, including water molecules, demonstrating definitive policy-making statements released decades earlier were simply wrong. The Genesis Rock presented in situ on top of a persistent pedestal, "as though it had been waiting for someone to retrieve it." Apollo 15 commander David Scott and lunar module pilot Jim Irwin, aware of the sample's potential value, were careful to photograph the find both before and after retrieval. AS15-68-11670 [NASA/JSC/ALSJ].

What does this mean for lunar origin and what does it say about the water at the Moon’s poles? The bulk composition of the Moon has long been recognized as a key constraint on models of lunar origin. A basic question is whether the Moon is made of the same material as the Earth or not. The new results indicate that it is and as such, is another contributory piece of evidence that the materials of the Earth and Moon were brewed in the same pot. Interestingly, this pot of material is distinct from virtually every other Solar System object (as near as we can tell based on limited information from the other planets). Whatever process formed the Moon, it involved objects that were created more or less in this neighborhood of the Solar System. The new results also suggest that both Earth and Moon had a significant component of water early in its history. Earlier studies had suggested that the terrestrial hydrosphere was a late addition, a veneer of cometary debris from deep space that was added to the Earth late in its history. We now know that this water was incorporated into the Earth very early, possibly from the beginning of accretion. The Moon shares this trait – and the same source of water.

So is the giant impact model of lunar origin still viable? The existence of water in the lunar interior is not a prediction of the giant impact model but as has happened previously, the model will probably be modified to accommodate the new findings. We have a tendency to imagine (and desire) simple systems in chemical and thermal equilibrium, in which materials and energy behave in a straightforward, predictable manner. But this event (if it occurred) was a singular one, possibly involving complex, chaotic behavior. Thus, some of the difficulties created by the new data will probably be explained away. A hypothesis elastic enough to be stretched to fit any new discordant observation isn’t particularly useful and certainly isn’t scientific.

How does this affect our thinking about the water ice trapped at the Moon’s poles? As we continue to find that the interior of the early Moon was more water rich than previously thought, we must add lunar water to the long list of possible sources for polar-trapped water. (As a reminder, the previous idea was that polar water was derived from external sources – the Sun via the solar wind hydrogen, water-bearing meteorites and comets). Could at least some of the water at the poles be of lunar origin? One problem that we still don’t understand is the geological age of the polar cold traps – they exist because the spin axis of the Moon is normal to the ecliptic plane. How long has the Moon been in this orientation? We suspect that the Moon has been stable for at least the last 2 billion years but water is being found in volcanic glass over 3 billion years old and thus, released before the current polar cold traps existed. So at least for now, it seems that the Moon’s own water is an unlikely contributor to the ice at its poles. But that story could change too.

The Moon’s surprisingly complex and interesting history continues to confound the experts. We may have already “been there” but we still don’t fully understand the Moon’s story and true potential.

Originally published May 14, 2013 at his Smithsonian Air & Space blog The Once and Future Moon, Dr. Spudis is a senior staff scientist at the Lunar and Planetary Institute. The opinions expressed are those of the author but are better informed than average.

"An Awesome Annular Eclipse!"

noreply@blogger.com (Joel Raupe) — Fri, 10 May 2013 23:26:00 +0000

A rising annular eclipse as witnessed by Geoff Sims (@Beyond_Beneath) from the Plutonic Gold Mine in Western Australia [Geoff Sims/Universe Today].

Images and Videos from Earth and Space

David Dickinson
Universe Today

A spectacular annular eclipse of the Sun was witnessed across Australia and the southern Pacific region early today. Morning dawned mostly clear across the Australian continent, and those who journeyed out to meet the antumbra of the Moon as the Sun rose across the Great Sandy Desert and the Cape York Peninsula were not disappointed. The rest of us watched worldwide on as Slooh and a scattering of other ad-hoc broadcasts delivered the celestial event to us via the web.

This was a challenging one. Although partial phases of the eclipse was visible across the entirety of Australia, Hawaii, and as far north as the Philippines and as far south as New Zealand, the track of annularity passed over some very remote locales. Stable Internet connections were scarce, and many photos and videos are still trickling in as die-hard eclipse chasers return “from the Bush.”

Read the full article, HERE.

Small Bouldery Crater

noreply@blogger.com (Joel Raupe) — Fri, 10 May 2013 21:20:00 +0000

A small crater, sporting a healthy population of boulders and a persistent higher reflectance surrounding ejecta blanket, on the rim of Planck W crater in the farside highland terrain. LROC Narrow Angle Camera (NAC) frame M1120363462L, field of view 500 meters across, resolution 0.5 meters, LRO orbit 17306, April 11, 2013 [NASA/GSFC/Arizona State University].

Drew Enns
LROC News System

The small crater featured today is a bit atypical. The crater's ejecta blanket has a higher reflectance than its surrounding, its interior is peppered with a number of boulders, and it has a poorly developed rim. Bright ejecta normally implies a fresh crater, but with the poorly developed rim it does not appear to be 'fresh'. So it could be either a secondary crater formed from a nearby cratering event, or it could be a fresh crater with an anomalously degraded morphology.

A better idea of the local geology might help with our interpretation.

The small crater of interest (upper right) in context with the rim and wall of Planck W (lower left), and a larger and likely younger crater further up the slope (upper left), with a more reflective ejecta blanket. An approximately 2.8 km wide field of view from a mosaic of the right and left frames of LROC NAC observation M172067030, spacecraft orbit 10491, October 1, 2011; angle of incidence 54.39° at 0.64 meters resolution from 61.39 km [NASA/GSFC/Arizona State University].

The small crater apparently sits on the rim of the larger crater Planck W. (the) ejecta blanket (of an adjacent small crater) is highly reflective - (it's) all you can see of the crater in the WAC context image!

Context for the LROC Featured Image, a high-resolution NAC view of the small crater barely visible at upper right in the field of view outlined above (shown in an earlier NAC observation, immediately preceding. The area of interest is on the slope of Planck W (55.44°S, 131.28°E). View cropped from LROC Wide Angle Camera (WAC) observation M110751697C (643 nm), orbit 1455, October 21, 2009; resolution 82.1 meters per pixel, angle of incidence 58.35° - spacecraft altitude 58.6 km [NASA/GSFC/Arizona State University].

In this case it appears that the crater is young since its ejecta blanket is still around. But then why does the crater not look morphologically fresh? It could be a form of physical mass wasting. Diffusion models of the lunar surface indicate that small craters are quickly degraded in terms of their morphology, but the ejecta blanket is not affected. Resulting craters might look very similar to today's Featured Image.

Look for more fresh craters in the full LROC NAC, HERE.

Related Posts:
Symmetric Ejecta
Beautiful Ejecta Patterns
Clusters

Earth and Moon share primal water source, raising problems for Giant Impact origin hypothesis

noreply@blogger.com (Joel Raupe) — Fri, 10 May 2013 18:48:00 +0000

Backscatter electron image of a lunar melt inclusion from Apollo 17 sample 74220, enclosed within an olivine crystal. The inclusion is 30 µm in diameter. Skeletal crystals within the melt inclusion are a fine mixture of olivine and ilmenite. Dark area in the lower-left is an ion microprobe sputter crater [John Armstrong, Geophysical Laboratory, Carnegie Institution of Washington].

PhysOrg

The water found on the moon, like that on Earth, came from small meteorites called carbonaceous chondrites in the first 100 million years or so after the solar system formed, researchers from Brown and Case Western Reserve universities and Carnegie Institution of Washington have found.

Evidence discovered within samples of moon dust returned by lunar crews of Apollo 15 and 17 dispels the theory that comets delivered the molecules.

The research is published online in Science Express today.*

The discovery's telltale sign is found in the ratio of an isotopic form of hydrogen, called deuterium, to standard hydrogen. The ratio in the Earth's water and in water from specks of volcanic glass trapped in crystals within moon dust match the ratio found in the chondrites. The proportions are far different from those in comet water.

The moon is thought to have formed from a disc of debris left when a giant object hit the Earth 4.5 billion years ago, very early in Earth's history.

Scientists have long assumed that the heat from an impact of that size would cause hydrogen and other volatile elements to boil off into space, meaning the moon must have started off completely dry.

But recently, NASA spacecraft and new research on samples from the Apollo missions have shown that the moon actually has water, both on and beneath its surface.

By showing that water on the moon and Earth came from the same source, this new study offers yet more evidence that the moon's water has been there all along, or nearly so.

"The simplest explanation for what we found is that there was water on the proto-Earth at the time of the giant impact," said Alberto Saal, a geochemist at Brown University and the study's lead author. "Some of that water survived the impact, and that's what we see in the moon."

Recent research, Saal said, has found that as much as 98 percent of the water on Earth also comes from primitive meteorites, suggesting a common source for water on Earth and the moon. The easiest way to explain that, Saal said, is that the water was already present on the early Earth and was transferred to the moon.

The finding is not necessarily inconsistent with the idea that the moon was formed by a giant impact with the early Earth, but presents a problem. If the moon is made from material that came from the Earth, it makes sense that the water in both would share a common source, Saal said. However, there's still the question of how that water was able to survive such a violent collision.

"Our work suggests that even highly volatile elements may not be lost completely during a giant impact," said Van Orman. "We need to go back to the drawing board and discover more about what giant impacts do, and we also need a better handle on volatile inventories in the moon."

Read the full article, HERE.

*Hydrogen Isotopes in Lunar Volcanic Glasses and Melt Inclusions Reveal a Carbonaceous Chondrite Heritage, A.E. Saal, et al. Science Express, 2013.

Northrop Grumman Completes Golden Spike Lunar Lander Study

noreply@blogger.com (Joel Raupe) — Thu, 09 May 2013 21:21:00 +0000

Northrop Grumman preliminary schematic shows a 'minimalist' ascent pod with surface habitat concept packaged in a 5-meter payload fairing. The pressurized compartments and propellant tanks easily fit in available space. Ascent thrusters are mounted on outriggers that are folded up to fit in the payload fairing and the landing gear is folded inward. Also shown are initial side and top views of the ascent pod “Pumpkin” and the surface habitat with crew members in pressure suits [Northrop Grumman].

Ben Evans
AmericaSpace

More than four decades since its last human-piloted craft touched down on the Moon, Northrop Grumman has concluded a feasibility study of a new commercial landing vehicle for the Golden Spike Company. It includes a novel, low-mass ascent stage concept, dubbed “Pumpkin”, and centers on the need to be packaged within a 5-meter payload fairing envelope, as well as offering insights into the kind of propellants necessary to accomplish Golden Spike’s goal of bootprints on the lunar surface by 2020.

Unveiled to the world last December, after several months of excited speculation, Golden Spike was founded by Alan Stern, associate administrator for NASA’s Science Mission Directorate in 2007-2008 and principal investigator for the agency’s New Horizons voyage to Pluto, and includes former Apollo flight director Gerry Griffin as chair of the board. It seeks to develop a capability to send astronauts from U.S. and foreign space agencies, corporations, governments and even private individuals on two-person expeditions to the Moon, at a cost of $1.5 billion. Within weeks, in January 2013, Golden Spike announced that it had contracted with Northrop Grumman to begin lunar lander design studies.

It was a notable move, for the Falls Church, Virginia-based aerospace and defense contractor is the only organization in the world to have successfully developed and flown a piloted craft to the surface of the Moon. Its Apollo lunar module ferried six pairs of astronauts to the dusty surface of our closest celestial neighbor between July 1969 and December 1972.

Read the full article, HERE.

Golden Spike, no longer 'Waiting for Godot' (April 16, 2013)

Golden Spike taps Northrup Grumman to design manned lunar lander (January 8, 2013)

Turning science fiction to science fact: Golden Spike

makes plans for human lunar missions (December 11, 2012)

Golden Spike Company formal announcement,
plans privately-funded commercial exploration of the Moon (December 6, 2012)

Chang'e-3 undergoing thermal vacuum testing

noreply@blogger.com (Joel Raupe) — Thu, 09 May 2013 20:54:00 +0000

Chang'E-3 begins thermal and hard vacuum testing at the AIT Hall facility of the China Aerospace Science and Technology Corporation in Beijing [CNSA/CLEP/CSA].

Emily Lakdawalla

The Planetary Society

A member of the NASASpaceflight.com forum has posted a large set of photos taken during Chang'E 3 thermal vacuum testing. They are all watermarked "China Space News" which is, as near as I can tell, a Chinese magazine -- I am hoping that the gigantic watermarks make it okay for me to post them.

I'm posting them here in the spirit of asking forgiveness rather than permission, because I haven't been able to figure out a way to ask for permission. (EDIT: Here's where the photos were originally posted online.)

Thermal vacuum testing is one of the last major testing programs that a spacecraft has to endure before it is cleared for launch. It is a test that must be performed on the actual spacecraft that is headed for space -- not on an engineering model -- and it has to be done with the spacecraft essentially completely assembled.

Read the full article, links, and more images, HERE.

Chang'e-3: The Chinese Rover Mission (May 4, 2013)

Chang'E-3 lander and rover expected in 2013 (January 10, 2013)
'China's grand plan for lunar exploration' (October 11, 2012)
ILOA to study deep space from Chang'E-3 (September 11, 2012)
Will China deploys first lunar rover since 1976? (April 29, 2012)
China's Long March to the Moon (January 14, 2012)
China plans lunar research base (May 11, 2011)
PRC continues methodical program (March 8, 2011)
Chang'E-2 arrives in mission orbit (October 9, 2010)
Dispatch from Chang'E-2: Sinus Iridum (October 4, 2010)
Chang'E-2 takes direct approach (October 1, 2010)
Chang'E-2 sets stage for future lunar missions (September 3, 2010)
Chang-E-1 research reported published (July 22, 2010)

Messy Crater in Mare Australe

noreply@blogger.com (Joel Raupe) — Thu, 09 May 2013 19:42:00 +0000

Fresh impact crater morphology can be messy! Deep interior of relatively small, unnamed fresh impact crater in Mare Australe. 708 meter wide field of view cropped from LROC Narrow Angle Camera (NAC) mosaic M189978900L R, LRO orbit 13045, April 25, 2012; resolution 60 cm per pixel, angle of incidence 57.76° from 58 km [NASA/GSFC/Arizona State University].

Lillian Ostrach
LROC News System

Cartoons illustrating the three stages of impact cratering (contact/compression, excavation, and post-impact modification) usually show the formation of a beautiful, bowl-shaped simple crater.

LROC NAC images reveal that while there are many bowl-shaped craters, there are also many craters that are not bowl-shaped or even very circular.

Today's Featured Image is an approximately 1 kilometer in diameter crater (45.661°S, 93.016°E) with a very irregular interior morphology. This crater exhibits a defined rim for all but a small portion of the crater (shown in the opening image). In this region, the crater wall is a jumbled mass of material that looks more similar to wall collapse than crater cavity excavation. The surrounding crater walls are covered with jagged blocks and impact melt veneer, and a 100 m wide melt pond with polygonal fracturing is located on the crater floor.

Near same width view of the 7.8 km wide LROC NAC mosaic M189978900LR [NASA/GSFC/Arizona State University].

Irregular crater morphology can be attributed to several factors. The impact process involves vast amounts of kinetic energy that may not be uniformly distributed throughout the target during impact. For example, a non-uniform energy distribution may be the result of an oblique impact, a steeply sloped target surface, or perhaps a low velocity secondary impact. Similarly, target properties, such as re-existing weakness or strength variations in the target rocks, may influence crater shape. Because the impact process is complex, it is often difficult to determine which factors dominate when studying craters with irregular morphologies. However, for today's crater, it is likely that some of the crater morphology irregularity is associated with the target slope; the impact occurred on the outer wall/rim slope of a degraded crater.

LROC Wide Angle Camera monochrome mosaic centered on the recent impact highlighted in the opening image [NASA/GSFC/Arizona State University].

Take a look at the full LROC NAC image, HERE, and explore the morphology of the young crater for yourself.

Related Posts:
Ejecta Starburst
Farside impact!
Komarov

Hemispheric view over the southern east limb of the Moon, centered on the location of the small impact crater on the 93rd meridian east. LROC WAC 100 meter Global Mosaic, LROC PDS image search tool [NASA/GSFC/Arizona State University].

Boulder Origin?

noreply@blogger.com (Joel Raupe) — Wed, 08 May 2013 17:10:00 +0000

Blocks litter the interior floor of an impact crater in the north farside highlands terrain. LROC Narrow Angle Camera (NAC) frame M187357438L R, LRO orbit 12679, March 25, 2012; angle of incidence 52.19° - resolution 1.76 meters per pixel, field of view 1.81 kilometers from 180.37 km [NASA/GSFC/Arizona State University].

Lillian Ostrach
LROC News System

Blocks littering the floors of impact craters are evidence that erosive processes continue to act on the Moon. Blocks are distributed along the boundary between the crater walls and the floor of von Bekesy F (52.8°N, 137.04°E, 20 km diameter) and also surrounding mounds located on the crater floor.

Today's Featured Image highlights boulders approximately 1 meter across eroding out of a floor mound and boulders that fell from somewhere along the crater wall or rim (52.86°N, 137.094°E). Observations of geologic relations between features are integral to developing a geologic story for an area, so it is important to make careful study of the different features. If we were to tell a story about the different boulders observed in the opening image, where should we start?

Interior view of von Bekesey F from 180 km, cropped from the full LROC NAC mosaic image [NASA/GSFC/Arizona State University].

There are clusters of blocky, fragmented material located on and surrounding the mound in the lower left of the opening image, and the boulders range from around 10 to 15 meters across. Observations of partially covered blocks on the mound support a mound origin.

Similarly, the distribution of roughly 10 meters wide boulders at the contact between crater wall and floor suggests that these boulders probably fell from higher up on the crater wall. But what about the boulders in between the mound and the floor-wall contact? At least one boulder is located at the terminus of a trail that can be traced back to the crater wall, but there are no other apparent relationships linking boulder to their origin.

LROC WAC monochrome mosaic centered on von Bekesy F crater, and asterisk notes location of opening image [NASA/GSFC/Arizona State University].

However, it may be possible that most of the boulders located in between the "boulder-rich" zones of the opening image originate from the crater wall side, simply because boulders falling from higher elevation will have a higher velocity component and will probably continue moving until the velocity and inertia components are lost (after the boulders hit the crater floor and begin to roll).

What do you think? Can you find evidence for boulder origin elsewhere in von Bekesy F in the full LROC NAC image, HERE?

Related Posts:
Perched boulders
Melt Boundary
Physics is Fun!

Boulder Tails

noreply@blogger.com (Joel Raupe) — Tue, 07 May 2013 17:56:00 +0000

Boulders greater than 1 meter across, and a few trails, surround the base of a mountain in the Schrödinger central peak ring. Boulder in lower left is around 55 meters across; mountain base is beyond the frame to the lower left. LROC Narrow Angle Camera (NAC) observation M187340587L R, image field of view 732 meters, resolution 0.77 meters per pixel, angle of incidence 79.15° from 36.56 km [NASA/GSFC/Arizona State University].

Lillian Ostrach
LROC News System

The Schrödinger impact basin is a geologically fascinating location, especially because of the variety of geologic features available for future exploration and it is the second youngest large basin on the Moon (just behind Orientale).

Discussed at length in several other Featured Image posts, blocky material, including boulders greater than 1 meter in diameter, can be used to help unravel geologic stories for an area.

In the case of boulders in Schrödinger, often the boulders originate from regions not easily accessible by robotic equipment or humans. Today's Featured Image highlights a distribution of boulders near the base of a part of the central peak ring (77.196°S, 133.178°E).

Context for the LROC Featured Image released May 8, 2013 - LROC Wide Angle Camera (WAC) monochrome (604nm) mosaic from 15 orbital passes, just after LRO completed its 10,000th orbit, September 3, 2011. Field of view (see section from mosaic below) roughly 50 km across [NASA/GSFC/Arizona State University].

LROC WAC mosaic covering a quarter of Schrödinger basin, show the 1400 meter high mountains rising over the mare-flooded interior contiguous with the greater peak ring structure [NASA/GSFC/Arizona State University].

Displaced fragmented blocks, such as those observed in the opening image, represent the movement of material from higher elevation to lower elevation. Most of the boulders range in size from ~15 to 25 m across, although the boulder in the lower left of the opening image is about 55 m across.

Today's boulders are derived from the higher elevations of a massif that is part of the Schrödinger central peak ring. Why is this fact geologically interesting? Because central peak rings form during the impact process; as the target is deformed and displaced during impact, material from depth is pushed toward the surface. Central peaks are usually formed in complex craters with diameters ranging from roughly 15 km to 200 km, but when the impact crater is larger than 200 km, central peak rings begin to form.

So, boulders originating from a central peak or central peak ring sample rocks from far beneath the lunar surface. How far? Scientists are not exactly certain, but there are several hypotheses and models undergoing testing with the help of LROC data.

HDTV still image captured from Japan's lunar orbiter SELENE-1 (Kaguya) in 2008. This oblique view was imaged as the vehicle orbited north, up over the Moon's farside from the far south [JAXA/NHK/SELENE].

Looking carefully, there is a boulder trail present (diagonally from lower left to upper right), and the boulder trail width is ~25 m near the upper right of the image. The irregular shape of the trail suggests that the boulder responsible for the trail was probably irregularly shaped. Additionally, the boulder trail is not discontinuous or "dashed", so it may be that the boulder responsible for the trail had a relatively low velocity. Similarly, there may be local slope variations in this area that promoted boulder rolling as opposed to boulder skipping.

Can you find a boulder that may be responsible for creating the observed boulder trail in the full LROC NAC image, HERE?

Related Posts:
A review of all things Schrödinger
Craters on the Schrödinger pyroclastic cone
New 3D CLSE flyover video: Schrödinger basin
Sampling Schrödinger
Sampling a Central Peak
Perched boulders
Scarps in Schrödinger
LOLA: Schrödinger Basin

Morpheus Unit B first fully integrated hot fire test

noreply@blogger.com (Joel Raupe) — Mon, 06 May 2013 19:57:00 +0000

Project Morpheus Hot Fire Test #8: On May 1, the Morpheus concept lander "Bravo Unit" was tested in a "hot fire" configuration, the first fully-integrated test of this second Unit. Built by Armadillo Aerospace, with the aim of developing a cutting edge vehicle for soft-landing 500 kg. payloads on the Moon, Unit A was lost following the failure of a real-time inertia measurement unit in August 2012.

Related Posts:
Morpheus and ALHAT teams, still hard at work (February 11, 2013)
Morpheus employs ALHAT in teather test #16 (June 13, 2012)
Project Morpheus lander - Soft Abort Test (May 11, 2012)
Morpheus Tether Test #10 (April 9, 2012)
Morpheus Tether Test #8 (March 14, 2012)
Project Morpheus methane Hot Fire Test #5 (February 29, 2012)
Morpheus lander in tethered flight tests (May 7, 2011)

Chang'e-3: The Chinese Rover Mission

noreply@blogger.com (Joel Raupe) — Sat, 04 May 2013 15:24:00 +0000

The Automatic Lunar Surface Exploring Vehicle, China's planned Chang'e-3 lunar rover, "a solar powered vehicle designed and built by the China Academy of Space Technology (CAST). The six-wheeled rover has a designed life of 90 days to explore three square kilometers, a total mass of 120 kg (with a 20kg payload capacity) designed to travel up to 10 kilometers." Illustration from "Will China deploy the first lunar rover since 1976?" - April 30, 2012.

Steve Nerlich
AmericaSpace.com

Currently scheduled for launch in December 2013, from the Xichang Satellite Launch Center in Sichuan province, the Chang’e 3 mission aims to land a Chinese rover on the Moon. If the mission is successful, it will be the first soft landing on the Moon since the Russian Luna 24 mission in 1976. Overseen by the China National Space Administration, the Chang’e program is following a step-wise approach to lunar exploration that could lead to the first taikonaut stepping onto the Moon by 2025.

The previous Chang’e 1 and 2 lunar orbiting missions, launched in 2007 and 2010, represented the first phase of the Chang’e program. Chang’e 3, to be followed by Chang’e 4, represent the second phase of the program, both involving rovers. The third phase, with Chang’e 5, will be sample-return mission and is currently scheduled for 2017. After that, it is anticipated that a new program will commence, which might culminate in a manned landing.

Chang’e is the name of a Chinese goddess who ascended to the Moon after consuming an immortality pill and there befriended a jade rabbit who was already a lunar resident. The elements of this legend were relayed by NASA to the Apollo 11 crew ahead of the first Moon landing in 1969. Michael Collins famously responded “Okay. We’ll keep a close eye out for the bunny girl”.

Read the full article, HERE.

Some Related Posts:

Chang'E-3 lander and rover expected in 2013 (January 10, 2013)
'China's grand plan for lunar exploration' (October 11, 2012)
ILOA to study deep space from Chang'E-3 (September 11, 2012)
Will China deploys first lunar rover since 1976? (April 29, 2012)
China's Long March to the Moon (January 14, 2012)
China plans lunar research base (May 11, 2011)
PRC continues methodical program (March 8, 2011)
Chang'E-2 arrives in mission orbit (October 9, 2010) Dispatch from Chang'E-2: Sinus Iridum (October 4, 2010)
Chang'E-2 takes direct approach (October 1, 2010)
Chang'E-2 sets stage for future lunar missions (September 3, 2010)
Chang-E-1 research reported published (July 22, 2010)

Dating Impacts

noreply@blogger.com (Joel Raupe) — Thu, 02 May 2013 20:06:00 +0000

Some boulders are exposed in an impact melt sheet. How can these boulders help geologists understand more about the timing of impacts? LROC Narrow Angle Camera (NAC) observation M1120322807L, LRO orbit 17301, April 11, 2013; field of view 1600 meters across [NASA/GSFC/Arizona State University].

Drew Enns

LROC News System

The impact process produces unimaginable amounts of energy! Some of this energy goes into melting rock, resulting is spectacular landforms. But not all of the rocks melt, and some are just heated up! Such is probably the case for the boulders we see in today's Featured Image. But how can these rocks be of use for geologists? On Earth, some enterprising geologists use boulders like these to date impact structures!

Geochronologists are a brand of geologists who study the ages of rocks. One way to get at a rock's absolute age is to measure its gas content. This method is particularly useful for igneous (and impact) settings. Rocks will accumulate gas over time as a result of radioactive decay of different elements, but these gases don't want to be there. If a rock is later warmed up past a specific temperature (which we term the closure temperature) the gases will start to escape. So if an impact event has heated some material above the closure temperature, the gas content of the rock will be 'reset.'

Closer look at the 'double' outcrop, at 0.65 meters per pixel, cropped from LROC NAC frame M154311644R, spacecraft orbit 7875, March 9, 2011; angle of incidence 45.27° - from 62.06 km [NASA/GSFC/Arizona State University].

Context image of the LROC Featured Image, May 2, 2013 - for boulders located on a terrace within Bridgman F (44.053° E, 141.825° E). Image width is 100 km [NASA/GSFC/Arizona State University].

Several gas systems are currently in use to obtain absolute dates for rocks, but there are two important ones for impact cratering. One measures the ratio of Argon 40 to Argon 39 (40Ar/39Ar dating). The other uses the Uranium, Thorium, Helium system ((U-Th)/He)). However, both utilize separate materials. 40Ar/39Ar dating benefits from having impact melt to sample. This is one of the methods used in the 1970's that dated Apollo samples and helped scientists understand lunar geologic time. But what if you have no impact melt? On Earth that might be more of a concern since impact melt might not last as long as boulders, and the (U-Th)/He might be the answer.

ASU graduate student Kelsey Young stands next to a boulder in Mistastin crater in Newfoundland. The red box outlines an impact melt zone between two boulders, which we can imagine are contextually very similar to the boulders in our Featured Image [Image credit Kelsey Young].

So Kelsey Young (and her colleagues) at ASU have come up with a new way to date a crater. They date boulders at impact sites using the (U-Th)/He method because the system has a lower closure temperature. This method has a few advantages. One is that boulders are easier to find than melt on Earth's surface. The other is that the system's lower closure temperature means that it is easier to reset the ages of these boulders.

The canonical age for Mistastin crater is 36 +/- 4 Ma, and the (U-Th)/He system came up with 32.7 +/- 1.2 which is within the error of previous estimates. So far this technique shows promise in matching the dates found using 40Ar/39Ar and adds another tool to those of us trying to understand impact cratering!

Landsat image of Mistastin crater in Canada (55.83° N, 66.3° W). The impact structure is about 28 km wide, shown here by the red ellipse [NASA/USGS].

Now that we have a better idea of how best to date impact craters, how might you find the absolute age of Bridgeman E crater in today's Featured Image? Of course, you'll have to get there first!

Look for more boulders and melt in the full LROC NAC, HERE.

Related Posts:
River of Rock
Absolute Time
Schiaparelli E

From ISS, "the Moon ushers in the dawn"

noreply@blogger.com (Joel Raupe) — Thu, 02 May 2013 00:52:00 +0000

"Moon ushers in the dawn," tweeted by ISS commander Chris Hadfield. The full field of view can be seen HERE.

Debris on the slopes of Benedict crater

noreply@blogger.com (Joel Raupe) — Wed, 01 May 2013 21:57:00 +0000

Debris flows on the slope of Benedict crater. Note material collected in small depressions, where boulders stand out as bright dots on the landscape. Recent LROC Narrow Angle Camera (NAC) observation M1120314888R, LRO orbit 17300, April 11, 2013; field of view 1200 meters resolved at 1.2 meters per pixel, downslope toward the upper right [NASA/GSFC/Arizona State University].

Drew Enns
LROC News System

Debris flows occur naturally on most sloped surfaces. This type of 'mass wasting' is actually very common on the Moon. In this case why are small piles of debris accumulating in clumps? This clumping is quite different from other debris flows which are sometimes misidentified as impact melt flows.

Perhaps the debris doesn't have enough energy to make it all the way down, or maybe the surface is not smooth.

Or perhaps the crater wall is not a smooth surface perhaps there are little bumps and depressions. We can see a hint of such undulations from looking at the 'texture' of the surface of the crater wall (and others).

Highly-resampled mosaic of scaled 25000 lines from the center of LROC NAC mosaic M1100280950L R, at a slightly higher resolution and narrower angle of illumination in the original, shows most of Benedict crater with the field of view shown at high resolution in the LROC Featured Image, released May 1, 2013 outlined by the yellow box. Note the asymmetry of the crater floor, an indication of a collapse, or slumping, of the crater's west wall. Spacecraft orbit 14487, August 22, 2012; scaled from 0.96 meters resolution at 26.77° angle of incidence, from 116.04 km [NASA/GSFC/Arizona State University].

LROC Wide Angle Camera (WAC) context view of 14 km diameter Benedict, well inside the interior of 210 km Mendeleev crater, at 4.345° N, 141.544° E. Field of view 58 km. [NASA/GSFC/Arizona State University].

Smaller scale LROC WAC context image shows Benedict, near center, and its place within 210 km Mendeleev [NASA/GSFC/Arizona State University].

Labeled oblique HDTV view of Mendeleev from the south, captured from Japan's lunar orbiter SELENE-1 (Kaguya) in 2007. View a full-size unlabeled, closer SELENE HDTV still HERE [JAXA/NHK/SELENE].

We can also see this uneven wall surface in Digital Terrain Models of young craters. The bumpy surface acts to trap debris in shallow depressions, inhibiting growth of the spectacular debris flows seen elsewhere. Mass wasting is a continuous process and in a few tens of millions of years perhaps the interior of Benedict crater will look more like some other craters we have featured.

Look for more debris along the crater wall of Benedict in the full LROC NAC, HERE.

Related Posts:
Dichotomy
Melt or Rubble
Crater Debris
Inside Catena Mendeleev
Mendeleev in full

April's Pink Moon with a Hat. Thursday's Partial Eclipse

noreply@blogger.com (Joel Raupe) — Fri, 26 Apr 2013 19:55:00 +0000

One of an excellent sequence of images of the Partial Lunar Eclipse, April 25, 2013, approximately seven minutes prior to maximum coverage. The face of the Moon is subdued in the penumbra of Earth's shadow, while the long and pointed umbra intersects the far north [Lupu Victor].

My Old Farmers Almanac (2013) reminds me the Full Moon of 25 April is traditionally called the "Pink Moon," but the transitory moment when the Moon was full, Thursday afternoon, came and went before moonrise, in the middle of the afternoon in North America.

Had I been in Romania, however, I might have been in Baia Mare, Maramures, with Lupu Victor, and the moment of "fullness" would have occurred simultaneous to the Moon's encounter with the edge of Earth's far-reaching shadow.

It appears projections of a dull eclipse made here the day prior might seem a bit of Aesop's "Sour Grapes," because from Lupu's well accomplished sequence published on his website, the Solar System's record cold temperature at Hermite crater may, if possible, have become colder still!

"On the evening of April 25, 2013, I prepared my 8 " telescope, and installed on the balcony at 21:00.

"It was a very beautiful and serene night, so I think I was very lucky as the weather was favorable for observations with, or without a telescope.

"I've photographed the event before, during and after till 11:29 p.m..

"I've replaced a few moments the Nikon camera, with the video camera Sony CX130 and I've filmed the Moon with zoom to see the shaded area and how craters looks in these conditions.

"By 00:30 I was able to put the first DSLR photos of the event. In this article, I've posted the same photos with Nikon D80, Exposure 1/500, but with a lower ISO of only 200, compared to the previous article photos, made with ISO 500.

"It was my choice to photograph all the event by these two ISO settings: 200 and 500.

"The images are in chronological order from 10:35 p.m. to 11:29 p.m."

View the images at Lupu's website, HERE.

The Monadnocks of Sinus Honoris

noreply@blogger.com (Joel Raupe) — Thu, 25 Apr 2013 20:39:00 +0000

A northwest-southwest oriented groove between two inselbergs in Sinus Honoris (12.276°S; 18.712°E), an embayment near the northwest extreme of Mare Tranquillitatis. LROC Narrow Angle Camere (NAC) frame M181944849L, LRO orbit 11796, January 12, 2012. Illumination angle of incidence 67.94°from the west, field of view roughly 5.8 km across, resolution in the original 1.21 meters per pixel from 122.13 km [NASA/GSFC/Arizona State University].

James Ashley
LROC News System

Most of the physical sciences are instructive in the art of piecing together observations made at vastly different scales. Note, for example, how climatologists look at pollen in soil samples to assess climate change through time on a global scale. Geologists use microscopes to examine mm-scale crystals in order to understand magma chambers many cubic miles in volume.

Astronomers attempt to make sense of subatomic particles in the context of the entire visible Universe. With this in mind, try to explain the sculpted mountains in today's Featured Image, located at the northwestern margin of Mare Tranquillitatis.

Field of view shown at high-resolution in the LROC Featured Image released April 25, 2013 is outlined in yellow in this Wide Angle Camera (WAC) monochrome (566 nm) observation M165726769C, swept up in orbit 9557, July 19, 2011. Field of view 45.8 km, resolution 58 meters per pixel from 40.97 km [NASA/GSFC/Arizona State University].

You may find that adjusting the scale is necessary. Indeed; we will have to zoom out until we can see a good deal of the lunar nearside before the features have the context they need to be understood. (Examine the image above and below to pull back for increasingly smaller-scale, wider-field of view LROC WAC context images.)

A mosaic of the LROC WAC image immediately above, stitched together to observations of the same latitude from one orbit prior and after, July 19, 2011. Field of view roughly 145 km [NASA/GSFC/Arizona State University].

The WAC mosaic context image released with the LROC NAC Featured Image covers a more familiar 1,500 km wide field of view (one that happens also to include four of six successful Apollo landing sites; Apollo 11, 15, 16 and 17) [NASA/GSFC/Arizona State University].

These mountains are members of a group of mare-surrounded highland structures nestled between Mare Tranquillitatis and Mare Serenitatis. Examination of the region will quickly reveal a strong northwest to southeast trending orientation to most of the upland features that points directly back to the Apennine Mountains, which form the southeastern rim of the Imbrium basin. Now we can see that this whole region was sculpted by ground-hugging forces unleashed in the terrible cataclysm that formed that basin. Imagine witnessing this awesome event from the Earth over 3 billion years ago; it would have been clearly visible to the unaided eye!

Isolated mountains like these, which rise from a surrounding plain, are often referred to by geologists as monadnocks or inselbergs ("island mountains," or "sky islands"). On Earth such features might be erosional remnants, but here in the Bay of Honor (Sinus Honoris) we know them to be isolated by surrounding mare deposits.

Click HERE to see the full NAC frame. Additional examples of large-scale features on the Moon can be explored with Four of a Kind in Catena Davy, Nearside Spectacular!, and A Scar in the Highlands.

A Very Partial Eclipse, 25 April 20:08:36 UT

noreply@blogger.com (Joel Raupe) — Thu, 25 Apr 2013 01:45:00 +0000

Apparitions like the Partial Lunar Eclipse April 25, 2013 demonstrate the miraculous improbability of lunar and solar eclipses on Earth actually are, because an exceptionally sensitive light meter will be needed to detect any apparition at all [NASA/GSFC].

They don't come more partial. In line of sight from Earth the Partial Lunar Eclipse of April 25 may serve to demonstrate the ephemeral depth of the umbra of Earth's long shadow.

As carefully mapped out in Espenak's schematic from Goddard Space Flight Center (PDF and HERE) The penumbral phase first contact (P1) occurs at 18:03:38 UT and terminates (P4) at 22:11:26 UT, totalling 4 hours, 7 minutes and 47 seconds.

The Umbral first contact (U1) occurs at 19:54:08 UT and ends (U4) at 20:21:02 UT, darkening the Moon's far north 26 minutes, 55 seconds. Maximum occurs at 20:08:36 UT.

The capstone of the International Year of Astronomy 2009, the Blue Moon Partial Eclipse New Years Eve, 31 December 2009 captured by Jean Paul Roux and featured as NASA's Astronomy Picture of the Day, 2 January 2011.

Getting Cracked at Weiner F

noreply@blogger.com (Joel Raupe) — Wed, 24 Apr 2013 20:07:00 +0000

An impact crater is caught in the process of disintegration, barely visible today on the complex terrace of Weiner F crater (40.881°N; 150.608°E). LROC Narrow Angle Camera (NAC) frame M169574198L, spacecraft orbit 10124, September 2, 2011. Illumination angle of incidence 46.95° from the southwest, resolution reduced from the original 43 cm per pixel from 30.02 km [NASA/GSFC/Arizona State University].

James Ashley
LROC News System

This small impact crater happened to form just a little too close to the widening edge of the Wiener F crater. Fault-slumping of the upper wall of Wiener F has cracked it along a series of linear, subparallel fractures, and the whole area appears to be in the process of down-slope migration. Eventually, if the process were to continue, the disintegration would be complete and the small superposed crater would no longer be recognizable.

The context images above and below show the location of this feature -- nestled within the slumping and fault-bounded eastern crater wall that has produced an irregular protrusion into the surrounding highland terrain. The occurrence of Wiener F within a former, older and larger crater is a coincidence of nature. Who says impacts cannot occur in the same place twice? Here we see three nested craters!

Context image from NAC frame, 1.3 km across; downslope to lower left [NASA/GSFC/Arizona State University].

The WAC global mosaic context image field of view approximately 48 km from west to east [NASA/GSFC/Arizona State University].

Click HERE to examine the full NAC frame. Other examples of fault-terraced crater walls can be found with Top of the Landslide, Aristarchus Spectacular!, and Post-impact Modification of Klute W.

Center crop from HDTV still centered on Weiner F, view toward the south over the farside anorthositic highland terrain from an estimated 100 km altitude in 2007. From Japan's lunar orbiter SELENE-1 (Kaguya) [JAXA/NHK/SELENE].

Other related posts:
Impact melt outside Weiner F (October 27, 2012)
Secondary melt on the rim of Weiner F (October 2, 2012)

Thin Crust Moon

noreply@blogger.com (Joel Raupe) — Wed, 24 Apr 2013 17:54:00 +0000

Map of the thickness of the Moon's crust from GRAIL mission gravity data. Mean thickness are estimated to be 34-43 km.

Paul D. Spudis
The Once and Future Moon
Smithsonian Air & Space

Imagine a system of molten silicate material, where low-density minerals float and higher density minerals sink. Minerals rich in iron and magnesium (such as olivine and pyroxene) will settle toward the bottom of the magma body while those rich in the elements aluminum and calcium (such as plagioclase feldspar) will float. Just such a scenario – on a global basis – is thought to have created the crust of the Moon.

Before Apollo, many believed that the Moon was a primitive, undifferentiated lump of cosmic debris. By studying the samples returned by Apollo 11, scientists identified small fragments of white, plagioclase-rich rocks (anorthosite). There are no known magma compositions corresponding to this rock type – anorthosite is created by removing low-density plagioclase from a crystallizing system and concentrating it by floatation. From the evidence of fragments in the lunar soil, large amounts of anorthosite were inferred to be present in the nearby highlands of the Moon. As the highlands make up more than 85% of the surface of the Moon, it was postulated that the crust of the Moon formed early in its history by global melting, an episode termed the “magma ocean.”

Expecting only minor volcanic activity and perhaps a local igneous intrusion, the concept of a global ocean of magma was surprising to most scientists. Given its small size and consequent paucity of radioactive heat-producing elements, the idea that most of the Moon might have melted and differentiated was astounding. The existence of an early magma ocean, which implied high-energy processes, provided us with clues to lunar origin. Once it was recognized that the Moon had a crust, it was important to gain an understanding of its composition and physical nature.

On subsequent missions, Apollo astronauts were tasked with laying out a series of seismic stations across the near side. These stations allowed us to measure “moonquakes” – both natural events as well as those created artificially by slamming spent rocket stages and satellites into the Moon. Seismic recording allowed us to infer the speed at which seismic waves traveled through the lunar interior. These estimated speeds indicated densities that implied composition, allowing us to deduce the probable chemical and mineral composition of the lunar interior.

The Apollo seismic network indicated that the crust of the Moon was about 50-60 km thick in the central near side, a surprisingly large value, especially compared to the thickness of the crust of the Earth (which varies from as thin as 5-10 km under the ocean basins to over 30 km in continental areas). Such a thick crust for the Moon led to the postulation of a global magma ocean, as so much anorthosite could only be produced under the conditions of near global melting. Subsequent studies incorporating gravity data from Lunar Orbiter and other missions suggested that the lunar crust is variable in thickness, with values exceeding 100 km in some regions of the far side highlands.

Re-analysis of the Apollo seismic data gave the first indication that those values might be overestimated. Using modern techniques on these old data, new analysis revealed that the crust might be thinner than we had originally thought, on the order of 40-50 km thick. This lower value of crustal thickness had some implications for estimating the bulk chemical composition of the Moon, but because it was considered to be a relatively minor adjustment, it caused no major difficulties for the rest of lunar science.

However, the recent GRAIL mission to the Moon (using high precision gravity mapping) ascertained the thickness of its crust to be 34-43 km. Why should this new value worry some scientists? Because we are now entering realms in which the new estimates of crustal thickness create consistency problems for other aspects of lunar science. A crust as thin as 35 km on the near side of the Moon implies that the largest impacts – the multi-ring basins – should have excavated considerable amounts of material from the layer below the crust, the mantle of the Moon. One might object that, as this region of the interior is inaccessible, we don’t know what the mantle would look like. But in fact, the density constraints imposed by the seismic and gravity data dictate that it must be a rock type rich in iron and magnesium, made up mostly of the minerals olivine and pyroxene. Such rocks are not unknown in the lunar collections, but they possess chemical and mineralogical characteristics indicating their origins at much shallower (crustal) depths. In other words, there does not appear to be any material from the lunar mantle in the Apollo collections. Given our obviously incomplete sampling of the Moon, should this be a problem?

Close view of a section of the central peak of Hausen crater (65.11°S, 271.5°E), among the few craters thought by some to have excavated more than 27 km and candidate for sampling below one of the thinner areas of the lunar crust. If the Moon's crust is as thin as GRAIL data indicate, however, why did basin-forming-impacts like Imbrium not appear to have excavated material from far deeper? LROC Narrow Angle Camera (NAC) mosaic M105100555L R, LRO orbit 643, August 16, 2009; angle of incidence 72.47° and 48 cm per pixel resolution, from 41.38 km [NASA/GSFC/Arizona State University].

Several Apollo landing sites (e.g., Apollo 14 and 15) were specifically chosen to maximize the chances of sampling ejecta from the enormous 1100 km diameter Imbrium basin (one of the biggest impact features on the Moon). Virtually any reconstruction of the dimensions of the excavation cavity of this basin indicates that it should have dug up material from tens of kilometers depth, much deeper than the new value of crustal thickness implied by the GRAIL data. So where is this debris from the mantle of the Moon? True enough, it is possible that it may have been missed during the limited exploration time available to the Apollo crews, but the astronauts were trained to recognize such rocks and none were found. Additionally, because we can map rock types by remote sensing (both from spacecraft and from Earth), we have an understanding of the regional distribution of rocks around these large impact features. Despite a 30-year, exhaustively detailed search of the Imbrium impact basin (an area larger than Texas), we have found no convincing evidence for mantle material on the surface of the Moon.

So where does this leave us? In science, new data can solve some problems but at the same time, it may also create new ones. Modern analyses of the old seismic data and new information on the Moon’s gravity field both suggest a relatively thin crust, with mantle material being very close to the surface (a few km) in some areas. On the other hand, none of the ubiquitous impact basins and large craters of the Moon show evidence for mantle material in their ejecta, either in the Apollo collections or in remote sensing data. Could our understanding of impact mechanics be completely wrong? How could an event that formed an impact crater thousands of kilometers across excavate only a few kilometers deep? Or are we misunderstanding the new gravity data?

Originally published April 24, 2013 at his Smithsonian Air & Space blog The Once and Future Moon, Dr. Spudis is a senior staff scientist at the Lunar and Planetary Institute. The opinions expressed are those of the author but are better informed than average.

The peculiar domes of Stevinus

noreply@blogger.com (Joel Raupe) — Tue, 23 Apr 2013 19:27:00 +0000

A distinctive positive-relief feature on the floor of Stevinus crater (32.760°S; 53.739°E). LROC Narrow Angle Camera (NAC) frame M113603383L, spacecraft orbit 1875, illumination is from the east, angle of incidence 57.67° field of view 1.9 km at 58 cm resolution from 55.68 km [NASA/GSFC/Arizona State University].

James Ashley
LROC News System

Today's image explores a portion of the Stevinus crater floor (southern hemisphere, nearside highlands). Here we see a topographic feature that can be found by the dozens throughout the area in many shapes and sizes. These mounded forms show positive relief upon a flat surface of ponded impact melt deposits (now solid).

Some are circular, while others show more irregular outlines. Some occur in clusters that appear to have coalesced, and others superpose one another. Some have smooth upper surfaces and others appear deflated with depressed central portions. The featured dome likely superposes an extension crack, indicating that it occurred after the crack formed.

What caused these peculiar mounds on the floor of Stevinus crater?

Some perspective on the peculiar dome of interest near center of this LROC Wide Angle Camera (WAC) monochrome (643nm) mosaic of three observations gathered in sequential orbits, November 20, 2011. Field of view roughly 40 km across. Angle of incidence 69.83° at 70 meters resolution from 50.66 km [NASA/GSFC/Arizona State University].

While not entirely clear without a better understanding of melt pond dynamics for still-molten deposits, we note that moderately viscous materials can behave in odd ways. The isolated occurrence of individual domes suggests molten behavior with each dome forming in-situ from a local source just beneath its position. Since the phenomenon is occurring in impact melt, we would be wrong to call this behavior volcanic. But something similar to volcanism in the sense that molten rock is locally "erupting" from an accumulated, still-hot deposit, might be appropriate for conceptual purposes. Perhaps isostatic readjustment of the crater floor "squeezes up" these blobs through holes or cracks in crust as the melt mass cools and thickens. This mechanism might explain why today's mound is centered over a fracture.

Reduced view of the LROC WAC mosaic from which the image immediately above it was taken shows the entirety of 71 km-wide Stevinus [NAXA/GSFC/Arizona State University].

Perhaps experiments with analog melts would be a good way to study impact melt behavior. Of course collecting samples is always recommended for any geologic study. What kinds of samples would be helpful for determining the solution to this mystery? Where should they be collected from and why?

Click HERE to see the full NAC frame. Other examples of odd features in impact melt deposits can be found with the Melt Fractures in Jackson Crater, Rippled Pond, and Anomalous Mounds on the King Crater Floor LROC Featured Image posts.

New views of the lava terraces of Bowditch

noreply@blogger.com (Joel Raupe) — Thu, 18 Apr 2013 18:56:00 +0000

A lava terrace rings the floor of farside crater Bowditch. LROC Narrow Angle Camera (NAC) observation M180493674L, LRO orbit 11718, January 12, 2012; a roughly 4 km-wide field of view at 1.74 meters per pixel resolution, angle of incidence 75.91° from 85.27 km [NASA/GSFC/Arizona State University].

Sarah Braden

LROC News System

Bowditch is a highly irregularly shaped farside crater partially filled with a mare basalt (25.0°S, 103.2°E).

Today's Featured Image is located along the inner wall of the crater, where the mare deposit meets the wall (24.935°S, 102.705°E). A section of the crater wall is visible in the upper left hand corner of the image, there is a step down in topography from left to right.

All along the inner wall of Bowditch there is a higher elevation ring, or terrace.

LROC WAC context image of mare-filled Bowditch crater. The yellow box outlines the field of view captured at high resolution in the LROC Featured Image released April 18, 2013. Field of view above roughly 38.3 km-wide. The LROC WAC context image accompanying the Featured Image released shows greater topographic relief at smaller scale HERE [NASA/GSFC/Arizona State University].

It is thought that this terrace is a marker of the highest level of liquid lava within the crater. As the lava cooled and solidified within the Bowditch depression it subsided into the center of the depression, causing a lower final elevation of mare basalt towards the center of the crater. Lava terraces such as this one provide important clues about the thickness, viscosity, composition, and cooling rate of lunar lavas and will help us better understand volcanism on the Moon.

View the entire LROC NAC frame to explore more of the Bowditch mare basalt deposit, HERE.

Related Images:
Bowditch Lava Terraces
A Lunar Dichotomy
The Mare-highlands Boundary in Tsiolkovskiy!