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Because of the very high surface temperatures on Venus (~450 oC) conventional semiconductor electronics will not work. Discussion of surface probes to Venus talk about using vacuum electronics, diamond semiconductors, and even clockwork mechanisms. But I haven't seen anything about simply refigerating the electronics with power from an RTG.

RTG technology is well understood, extremely reliable, and is long-lived (44 years so far in Voyager-1). The challenge, would be to redesign the RTG for the very high sink temperature. The plutonium source decays with 5.6 MeV of energy, so the temperature of the driving source is effectively infinite and presumably metallic thermocouples still work at elevated temperatures. Admittedly, the RTG it will likely be quite inefficient in terms of electrical output, but could this not be used to refrigerate a small amount of carefully insulated electronics for critical sensors and communications?

Maybe we could have the excess heat from the RTG drive a Stirling engine for locomotion?

Wouldn't it be wonderful to have a 'Perseverance' or a 'Curiosity' wandering around on the surface of Venus for a few years!

Does NASA have studies along these lines with an RTG and refrigerated electronics?

Cornelis
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Roger Wood
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    A few months? More like a few days. Which is better than we have done so far. – ikrase Feb 22 '21 at 02:00
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    Refrigeration may take an awful lot of power. I'm not sure. – ikrase Feb 22 '21 at 02:01
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    The surface temperature of Venus is actually lower than the cold side temperature of some thermocouple designs (I think mostly intended for use with reactors, with high power output for the radiator area), and the dense atmosphere would make an excellent heat sink. You wouldn't want to add a Stirling engine in the path though, you'd just be increasing the cold side temperature further. It might be useful in parallel as a more efficient way of providing mechanical power though. – Christopher James Huff Feb 22 '21 at 02:17
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    For example, https://www.osti.gov/servlets/purl/5335393 has a reactor-based system design that rejects heat at 800 K, the ambient temperature on Venus being 737 K. – Christopher James Huff Feb 22 '21 at 02:24
  • @ChristopherJamesHuff Yes!!! With 100 kW of electrical power from that reactor, we could do some real off-roading! – Roger Wood Feb 22 '21 at 02:39
  • @RogerWood gonna be a problem for a heat engine to deliver its rated output when the temperature differential between its radiators and its environment is greatly reduced, right? – Starfish Prime Feb 22 '21 at 08:55
  • @StarfishPrime mmmh... usually you want small temperature differences between the environments and the corresponding radiator or absorber at either end. So the thick Venusian atmosphere is an advantage in that respect. But it does take a lot of work to pump heat from say, 400K to 750K, between the two ends. So you won't be able to cool very much electronics and it will have to be well insulated from the Venusian atmosphere. That reference in 'SpaceDisgrace" answer is very good. – Roger Wood Feb 22 '21 at 18:36

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Here's an interesting paper that touches on this from the John Glenn Research Center. It appears that it is possible to use RTG technology to move, power, and cool the electronics but it's not efficient. The electronics would still be operating at their maximum rated temperatures.

SpaceDisgrace
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