High-Temp Electronics For Venus Exploration, recent advances Options

[dtolman]

(MOD NOTE: Started a new topic for this discussion to continue. Please remember the 'no sci-fi engineering' provision of rule 1.9. Have fun!)


Also, since I'm thinking about surface operations on Venus, the state-of-the-art in high temperature electronics has advanced quite far in the past decade.
Its now possible to buy off the shelf chips from vendors designed to operate at the 250-300 C range.

Meanwhile basic functionality has been tested at and beyond the temperatures needed for long-term surface operations on Venus:
http://www.grc.nasa.gov/WWW/SiC/
http://www.gizmag.com/extreme-silicon-carb...ctronics/16410/
http://www.grc.nasa.gov/WWW/SiC/publicatio...Contact2010.pdf

Another decade or so and a long-term Venus lander could be possible with (practically) off the shelf electronics!

[SpaceListener]

If the chamber where it is stored electrical instruments has a static insulation and the air is emptied, the internal temperature would be lower than outside? I think the heat sink in Venus is not useful because the atmosphere is warmer outside than the inside of chamber.

[dtolman]

If you can get electronics running at ambient, just leave them exposed* and cool them off with a fan. After all - thats what we do with PCs here when they run hotter than the atmospheric temp

On a more realistic note, if memory serves, the latest surface proposals were nuclear powered and cooled with a Stirling Cycle heat engine. Of course those missions anticipated a 200 C interior and 500 C exterior - a 300 C differential. I imagine the power requirements for running the heat engines would be lower if you can get the electronics closer to 400 C and a 100 C - or smaller - differential, and more than make up for the hotter electronics.

*Now we just need high temperature, acid rain resistant electronics

[Robotbeat]

If you can get electronics running at ambient, just leave them exposed* and cool them off with a fan. After all - thats what we do with PCs here when they run hotter than the atmospheric temp

On a more realistic note, if memory serves, the latest surface proposals were nuclear powered and cooled with a Stirling Cycle heat engine. Of course those missions anticipated a 200 C interior and 500 C exterior - a 300 C differential. I imagine the power requirements for running the heat engines would be lower if you can get the electronics closer to 400 C and a 100 C - or smaller - differential, and more than make up for the hotter electronics.

*Now we just need high temperature, acid rain resistant electronics

Indeed, those actively cooled mission proposals are what my mentor has been working on. But the power requirements are pretty big for active cooling, since your heat dump is so hot. That means completely custom high-power radioisotope... Flagship class funding requirement, but at best a Discovery-class risk level, so unlikely to fly before I retire.

But one good thing about Venus's atmosphere is that because it's so dense, it should carry /extra/ heat away rather well, better than on Earth. Of course, the problem is that you have to start out at ~450C or so....

Also, although there is no acid rain droplets on the surface, you do have the products of dissociated sulfuric acid, so corrosion is still a problem. But a better problem to have than the incredibly high temperatures.

[dtolman]

Thinking about it, perhaps if the goal is electronics that work in near-ambient temperatures, then the cooling schemes where they need to refrigerate the electronics is all wrong. If the goal is to get to 400+C rated electronics, than a totally different cooling system will be needed. Once you get to the point where the electronics are hotter than the outside air, which at 400 C rated electronics might be true for highland landings, you can switch to less exotic methods - passive radiators, or some kind of liquid cooling (sodium?).

I don't know much about more passive cooling techniques, but I imagine that a sodium (or some other high temperature liquid) cooled electronics bay would be a lot cheaper, lighter, and require less power than a Stirling Engine.

[Robotbeat]

Thinking about it, perhaps if the goal is electronics that work in near-ambient temperatures, then the cooling schemes where they need to refrigerate the electronics is all wrong. If the goal is to get to 400+C rated electronics, than a totally different cooling system will be needed. Once you get to the point where the electronics are hotter than the outside air, which at 400 C rated electronics might be true for highland landings, you can switch to less exotic methods - passive radiators, or some kind of liquid cooling (sodium?).

I don't know much about more passive cooling techniques, but I imagine that a sodium (or some other high temperature liquid) cooled electronics bay would be a lot cheaper, lighter, and require less power than a Stirling Engine.

If you can get the electronics to work at just above ambient /reliably for a long time/, then cooling isn't much of a problem in Venus's dense atmosphere. But that's a pretty big if. And the Raytheon stuff isn't "rated" for 400C, it's been operated there for some (presumably quite limited) finite period of time. A problem with the highlands, though, is that it's not really a good place to land something like a seismometer because it looks much rockier than most of the Venera landing sites.

[Xcalibrator]

A RFI http://go.usa.gov/jtdJ has been issued in FEDERAL BUSINESS OPPORTUNTIES for a new prize competition being considered by NASA. As currently envisioned the Extreme Environments Challenge would focus on finding innovative solutions to the problems surrounding the survival and operations of scientific probes in extreme environments, such as on the surface of Venus where temperatures approach 500° C, the atmospheric pressure is about 90 times that at the Earth’s surface, and the atmosphere is corrosive. The approach being considered would entail a series of competitions that would focus on 1) electronics and mechanisms, and 2) thermal management, and 3) power with a culminating systems integration competition.

Sorry for the very late notice (RFI responses are due tomorrow); it took a couple weeks to get validated to post here after I registered.