October 4th, 2008
Using space robots to fix ailing satellites?
According to Canadian engineers at Queen’s University, there are now more than 8,000 satellites in orbit around the Earth. Of course, if they stop to work correctly, these satellites will not be able to be repaired from the ground and will become space junk. So these researchers have developed a robotic repair system to fix ailing satellites. Right now, they’re writing software to track these satellites. Their tracking software would then be used by an Autonomous Space Servicing Vehicle (ASSV) ‘to grasp the ailing satellite from its orbit and draw it into the repair vehicle’s bay. Once there, remote control from the ground station can be used for the repair.’ I’m somewhat skeptical about the idea, considering that the satellites in orbit have been launched by various countries and companies using very different technologies. But read more…
You can see above a computer-generated image of our planet showing debris objects in orbit currently tracked by NASA. These debris are shown as white dots. (Credit: NASA Orbital Debris Program) For more information, please read the FAQs and browse this Photo Gallery. The space map shown above has been picked from this page and here is a link to a larger version of this image.
This research work has been led by Electrical and Computer Engineering professor Michael Greenspan and other graduate students of his Robotics Computer Vision Lab, Michael Belshaw, Limin Shang and Babak Taati.
Here is a quote from Greenspan. “‘These are mechanical systems, which means that eventually they will fail.’ But because they are many thousands of kilometres away, the satellites are beyond the reach of an expensive, manned spaced flight, while Earth-based telerobotic repair isn’t possible in real time. Dr. Greenspan’s solution to this problem is the development of tracking software that will enable an Autonomous Space Servicing Vehicle (ASSV) to grasp the ailing satellite from its orbit and draw it into the repair vehicle’s bay. Once there, remote control from the ground station can be used for the repair, he explains. ‘The repair itself doesn’t have to be done in real time, since everything is in a fixed position and a human can interact with it telerobotically to do whatever is required.’”
The Queen’s team is now working to develop the ASSV with the aerospace company MDA Space Missions which is a subsidiary of the McDonald-Detweiller Associates Corporation and which earlier built the Canadarm and has been responsible for all Canadian systems in the International Space Station.
I guess this space robotic system will not be in the air before a while. Even finding — then grasping — a satellite is a serious challenge. “Computer vision is the main technical challenge of grasping the satellites, Dr. Greenspan continues. Since these objects circle the globe in ‘geosynchronous’ orbit, their speed is synchronized with the Earth’s rotation. The robotic system must recognize the satellite first, then determine its motion and match that motion before grabbing it.”
For more technical information, you can read “Satellite Pose Acquisition and Tracking with Variable Dimensional Local Shape Descriptors (PDF format, 6 pages, 340 KB). This paper was presented during the IEEE/RSJ IROS Workshop on Robot Vision for Space Applications held in August 2005 at Edmonton, Canada.
If you’re less skeptical than I am, please drop me a note.
Sources: Queen’s University news release, October 2, 2008; and various websites
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