[AR] Re: Mars Rover Power source
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Tue, 9 Mar 2021 12:37:22 -0500 (EST)
On Tue, 9 Mar 2021, John Stoffel wrote:
Since the Stirling cycle power systems have passed 14+ years of
continuous operation, and seem to give more power per kg of mass, why
wasn't this used on Perseverance? Or is it planned for any future
rovers? Or other orbital missions?
The big-budget "flagship" missions are severely averse to new technology,
where "new" means "anything that hasn't flown before", no matter how long
people have been testing it on the ground. Better to have a mission
that's half-crippled by design, using old tech that everyone agrees is
credible, than to take the slightest chance that something new might
malfunction (and then *you* would get the blame).
For all his sins, one thing that Dan Goldin got right was the need for an
organized program of flight demonstrations of important "new" technology,
to establish once and for all that it would work in space. After decades
of sitting on the ground waiting for a chance, ion propulsion suddenly
became acceptable for science missions when Deep Space 1 flew it. Alas,
political support for the Deep Space program didn't last.
(Even if it had, anything to do with RTGs is expensive, and their Pu-238
fuel is in short supply, so doing a flight-demo mission for Stirling RTGs
would face unusual obstacles.)
It would seem that having a bigger power budget would be a good thing
for any rover or orbiter, if only so you can push higher power
transmissions back to earth more easily.
Except in the far reaches of the outer solar system, orbiters generally
are better off with solar arrays, which produce *much* more power per
kilogram. RTGs make sense only when there's some problem with solar
power: inadequate sunlight due to distance, long cold nights with no
sunlight, or problems with dust accumulation on solar arrays. (The big
thing that's missing from current Mars landers/rovers is an organized
attempt to test dust-removal technologies; removal by natural winds is
helpful but not entirely reliable.) But yes, if you need isotope power,
then *better* isotope power would definitely be a good thing.
Henry
Other related posts:
