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Americium: How a small element could power the next century of space exploration
(interestingengineering.com)
this post was submitted on 17 Nov 2025
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Technology
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Using it seems way more preferable to just letting it sit in casks.
That seems a little ridiculous though. All that friction requires a lube that'll last "generations." In space, without gravity, and at incredibly low temperatures.
Yeah, but there are many good options. Magnetic alignment can keep things from touching most of the time, maintaining very good movement without friction. Graphite is a great lubricant and works even in very cold environments, not to mention it will not be all that cold given the heat passing through the system. Redundancy is also a big part of the design, making failures much less impactful. And using sterling engines for the highest draw part of the lifetime of a probe with peltier style generators there for later would allow a failover to a solid state system at lower efficiency.
Sterling Engines are usually piston driven, no? I’ll admit, I’m not up to snuff on alternative designs of the Sterling engine.
Magnetically aligned or not, you still have to seal the piston to the chamber to stop blow-by. Friction and lubrication would still come into play, wouldn’t it?
And Stirling engines run on gases, so the contraption would have to be sealed. Not insurmountable, and I love me some Stirling engine... IANAE but it seems a challenging choice for a device which hopes up run for decades or a century.
Not necessarily. You don't actually need the fluid to be perfectly sealed out, just slowed down a lot. This means that you could run it open but with very close tolerances and there would be almost no leakage. You just need to make the gap small enough for the leakage to be trivial.
As for magnetic alignment, that is all about maintaining smooth operation without losing efficiency to friction. Instead of a guide with friction you could use magnetic attraction to keep things aligned.
Good point on the lubricants, but given the potential profits, it's already being worked on. https://www.nyelubricants.com/space
Well, not at low temperatures, stirling engines still need heat.
My understanding of space engineering is that getting rid of heat is a bigger problem. Makes me wonder how much of efficiency of Stirling engines are lost due to extra weight and complexity for heat exchangers and radiators.
You think thermoelectric generators are going to struggle with low temperatures?
If there's one thing we can practically guarantee, it's the heat output lol
I'm not an engineer in this space, so i'll leave it to more knowledgeable people to poke holes in my argument.
I see what you did there.
Not thermoelectrics, but sterling engines. But fair point about the heat.
Voyager I and II are 48 years old running on thermoelectric generators. that’s amazing. They are winding down because the half life of plutonium means there is much less power than when new.
I can see future probes lasting even longer with americium as a fuel source
But introducing moving parts for a sterling engine? In space? And expect it to last like that? Seems unlikely