One of the big problems in the vacuum of space is getting heat away. RTG that rely on a temperature differential from the hot to the "cold" side to produce electricity will probably suffer a lot from bad cooling. And it seems, the "cold" side of those RTG can get quite hot accodring to anwers to this question: How hot was the surface of RTG radiator which powered ALSEP on Apollo-12?

There are plans to send probes to the icy moons in our solar systems.

Would potential RTGs on probes that land on the surface of those icy moons or even use the heat to melt through the ice benefit from the advantages of water-cooling? If yes, how much more efficient (and therefore smaller/lighter) could they be?

  • $\begingroup$ It just dawned on me, that an RTG melting the ice on a moon without (or with a very thin) atmosphere would immediately sublimate it, so no liquid cooling but sublimation. Now I'm trying to wrap my head around how this would affect the whole system... $\endgroup$
    – TrySCE2AUX
    Jul 18 at 12:20
  • $\begingroup$ In such conditions the primary focus for an RTG is not electricity but to keep things warm. $\endgroup$ Jul 18 at 12:29
  • $\begingroup$ @user3528438 The "T" in RTG usually stands for "Thermoelectric" so if the primary focus for a radioisotope device is keeping warm then one is not talking about an RTG proper, but a radioisotope thermal generators which unfortunately would have the same acronym. Hmm... $\endgroup$
    – uhoh
    Jul 18 at 21:16


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