SoylentNews is people
SoylentNews
On Wednesday, April 19th, in a seminar titled "An Air-Breathing Metal-Combustion Power Plant for Venus in situ Exploration", NASA engineer Michael Paul presented a novel idea where existing technology could be used to make longer-duration missions to Venus.
To recap the history of Venus exploration, very few probes have ever been able to explore its atmosphere or surface for long. Not surprising, considering that the atmospheric pressure on Venus is 92 times what it is here on Earth at sea level. Not to mention the fact that Venus is also the hottest planet in the solar system – with average surface temperatures of 737 K (462 °C; 863.6 °F).
Hence why those few probes that actually explored the atmosphere and surface in detail – like the Soviet-era Venera probes and landers and NASA's Pioneer Venus multiprobe – were only able to return data for a matter of hours. All other missions to Venus have either taken the form of orbiters or consisted of spacecraft conducting flybys while en route to other destinations.
[...] "What can you do with other power systems in places where the Sun just doesn't shine? Okay, so you want to get to the surface of Venus and last more than a couple of hours. And I think that in the last 10 or 15 years, all the missions that [were proposed] to the surface of Venus pretty much had a two-hour timeline. And those were all proposed, none of those missions were actually flown. And that's in line with the 2 hours that the Russian landers survived when they got there, to the surface of Venus."
The solution to this problem, as Paul sees it, is to employ a Stored-Chemical Energy and Power System (SCEPS), also known as a Sterling[sic] engine. This proven technology relies on stored chemical energy to generate electricity, and is typically used in underwater systems. But repurposed for Venus, it could provide a lander mission with a considerable amount of time (compared to previous Venus missions) with which to conduct surface studies.
For the power system Paul and his colleagues are envisioning, the Sterling[sic] engine would take solid-metal lithium (or possibly solid iodine), and then liquefy it with a pyrotechnic charge. This resulting liquid would then be fed into another chamber where it would combined with an oxidant. This would produce heat and combustion, which would then be used to boil water, spin turbines, and generate electricity.
Such a system is typically closed and produces no exhaust, which makes it very useful for underwater systems that cannot compromise their buoyancy. On Venus, such a system would allow for electrical production without short-lived batteries, an expensive nuclear fuel cell, and could function in a low solar-energy environment.
Stirling engines could extend the mission durations.
(Score: 2) by frojack on Monday April 24 2017, @06:23PM
How does that help you withstand the pressure and temperature and corrosive gases?
For the durations being talked about, hermetically sealed interiors and inert-ish external mechanisms woul last long enough to accomplish the mission. You make it thick enough to give you the time you need.
But making an electrical generator system, Stirling engine or any other, doesn't get you closer to any working electronics. 462 °C is well above the melting point of any common solder, you'd have to use Au82, and hope you squeek by under its melting point.
Even the simplest connections become a major engineering task. And that says nothing about the circuit components themselves. Most of those are not likely to survive at these temperatures.
It seems to me the research is on the wrong track. Making steam (via combustion no less) isn't the problem there. You've got all the heat you need right outside your shell. Boiling point of water at 90 bar pressure is around 300C, significantly below ambient.
Rather than trying to make electricity they should concentrate on cooling.
They should be finding ways to radiate heat faster than they absorb it, so that the interior of the vehicle could be maintained at a working temperature in keeping wiht the technology at hand. I don't know how you keep something cooler than ambient without some method of collecting and concentrating heat to temperatures significantly above ambient so that simple radiation can be employed.
No, you are mistaken. I've always had this sig.