During my visit to Google Lunar X PRIZE team Astrobotic at Carnegie Mellon University in Pittsburgh last week, I got team member and CMU mechanical engineering student Charlie Muñoz to explain how the team is solving a major technical challenge.
The lunar night lasts 14 Earth days, during which surface temperature drops below the temperature of liquid nitrogen, to around -233 degrees Celsius, or -387 degrees Fahrenheit. Any moon robot, such as the one team Astrobotic is building, had better not have water or even water vapor in its onboard batteries if it wants to get through those 14 days in deep freeze and have any hope of reviving when the sun again warms its solar panels.
The Soviet Lunokhod rovers of the 1970s solved the problem by keeping warm with radioactive isotopes. That’s not going to be option for a private university-based team since the appropriate isotopes are tightly controlled.
And when the sun does come out again, the temperature on the lunar surface rises well past the boiling point of water, to about 253 degrees Fahrenheit or 123 degrees Celsius. Staying cool enough to prevent electronic circuits from being cooked to death then becomes the major challenge.
What’s a poor lunar robot to do? Watch my video interview with Muñoz for Atrobotic’s solution.
Hi Mr Belfiore,
Thanks for posting the interview!
You are correct on your reported temperature for the moon. At the bottom of the darkest crater on the south pole, the moon does approach -233C. We are designing for an equatorial mission, and don’t plan on going to any greatly shadowed regions, so our night temperatures will be in the -160’s or so. -173C what we generally tell people. We tested our cells to -180C just to be sure.
Thanks for the clarification!
Very cool video! Thanks for sharing that. How long did you get to meet with the team? What did you think was the most interesting part of the rover?
Hi Derek. Glad you like the video! I spend a couple of days with the team, including some time out in the field at Robot City, where CMU test drives all its robots. I found the rover’s ability to track its distance traveled (to comply with the X PRIZE 500-meter-traveled requirement) very interesting. Since there will be a lot of “slippage” in the lunar dust, or regolith, counting wheel turns is not a reliable method of tracking distance traveled. Instead the rover will use a system of “visual odometry,” using its binocular vision to calculate distance traveled as it moves along and its visual field changes.