If a rover on Mercury "roves" only at night when the surface is freezing cold, and before dawn unfolds a Sun shield of a few square meters above itself, under which it stays put all day. Would the surface under the shield still get hot by horizontal thermal conductivity in the surface materials?
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7$\begingroup$ Have you looked up the length of a day on Mercury? $\endgroup$– HobbesCommented Mar 28, 2017 at 18:08
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$\begingroup$ @Hobbes How does the length of day matter, mysteriously rhetorical Hobbes? $\endgroup$– LocalFluffCommented Mar 28, 2017 at 19:18
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2$\begingroup$ A day length of 58 Earth days gives rather more time for thermal conductivity to warm up your patch of shade than would a 12-hour day. $\endgroup$– HobbesCommented Mar 28, 2017 at 19:27
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$\begingroup$ What about a heat shield below the rover and thermally isolating legs to lift the wheels of the rover from the ground? But the heat shields should have multiple layers. Transport of heat by the atmosphere is neglible, its pressure is lower than the best laboratory vacuum. But the very long duration of a day will be a problem. Is the available light at night sufficient for roving? The electronics of the rover should be kept warm for regular operation. $\endgroup$– UweCommented Mar 28, 2017 at 19:29
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As Hobbes pointed out, the ground under the rover will eventually warm up. Any thermal barrier only slows down the heat transfer. It would eventually cook from below.
The only thing that I can think of would be to put the rover up on stilts and have heat shields both above and below with radiators pointing outward between the two shields. The radiators are to dissipate the heat coming up the stilts and the heat absorbed by the heat shields.
Aside from the mechanical issue of lifting the rover a few meters off the ground every "day," the rover would have to cart all of that around. I just don't see that happening.
If we need a ground mission, I think we will need to drop the rover after "dusk" as soon as the ground is cool enough, run it away from the sun as much as you can and then play taps in a month when it gets cooked.
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$\begingroup$ Mercury's equatorial rotation speed is 85 kph. Outrunning the dawn would only work near the poles, where there are some eternally shadowed craters around anyway. Without shields, rover Icarus could make 26 Earth days long excursions between Sols, and longer still by driving west and using long shadows. $\endgroup$ Commented Mar 29, 2017 at 10:06
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$\begingroup$ I had not thought of outrunning the dawn, just in extending the mission a few hours longer before the rover fried. $\endgroup$– ShadoCatCommented Mar 29, 2017 at 16:27