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Space Exploration

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    $\begingroup$ Bear in mind that the asteroid is revolving, with its surface in direct sunlight for half of its 4.3 hour rotation period. Depending on latitude, the collected surface sample may have already cycled many times between -100 and +100 degrees C. $\endgroup$
    – Russell Borogove
    Commented Sep 8, 2016 at 23:25
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    $\begingroup$ @RussellBorogove yep, thus the cautious wording "If it gets hotter than it does while on Bennu, the science may be compromised." Ballparking: $T^4 = TSI_{max} / \sigma \epsilon$ where $TSI_{max} = 1368/ 0.9AU^2 \ W/m^2 $, $\epsilon \approx 0.96$ and $\sigma \approx 5.67x10^{-8} \ W/m^2K^4$ gives about 420K or 150C, but material down a few cm may never get nearly that hot since the packing will be very loose in low gravity making thermal conductivity quite low. Since temperatures associated with reentry are of order 3000K for say 100 sec, the capsule is quite a feat of engineering! $\endgroup$
    – uhoh
    Commented Sep 9, 2016 at 1:20