This answer to Has NASA “gone south”? Why are astronauts needed to explore the Moon's south pole? and the question What would happen if an Apollo astronaut landed on Pluto? both touch on issues of walking and or driving on an extremely cold surface which might contain ice (water or other compounds) that can liquify and refreeze, and raise issues of getting stuck.

Is there any way to estimate how much heating power (Watts total, or Watts/m^2) would flow out from a rover's wheel versus an astronaut's boot?

Would one be significantly more likely to have problems with refreezing, or even slipping on "wet regolith" while trying to climb in or out of a crater?

There may not be a lot of data on the astronaut boots of the future, but considering that NASA's "new mission" is to walk on the Moon's south pole, boot design is probably going to be looked at. In the mean time there may be information about the Apollo boots for the Moon, or newer "ISS space walking-only boots" from the perspective of heat loss.

  • $\begingroup$ No fluid water may exist in the vacuum on the Moon, the heating power will increase the sublimation rate of the ice. $\endgroup$
    – Uwe
    Mar 28, 2019 at 14:17
  • 1
    $\begingroup$ @Uwe you're talking about equilibrium physics. When you melt water in a vacuum it can certainly form a very thin wet layer (some people believe ice skates melt a very thin layer due to increased pressure rather than temperature). In a vacuum, liquid water will boil rapidly, but you can't just say "it won't exist". It can certainly exist for a short time. Liquid waste vents from spacecraft into space certainly pass through a droplet form; this is known and well documented, right? $\endgroup$
    – uhoh
    Mar 28, 2019 at 14:23


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