[AR] Re: practical electric thruster propellant and power?
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Tue, 9 Feb 2016 17:36:53 -0500 (EST)
On Sat, 6 Feb 2016, Ed LeBouthillier wrote:
My larger point is that there are other kinds of electrical propulsion
worth considering.
Quite true. For example, anyone who's thinking electric propulsion but
hasn't looked at electrothermal systems is missing what might easily be
the best answer for near-term missions. Ion thrusters get a lot of the
press coverage because they've got Really High Isp, but as noted earlier,
that isn't necessarily what you want.
Dave W. might start by looking at surveys of different types of
propulsion available before settling on a particular one. Each has
different strengths and weaknesses.
To which I would add that you want to look very carefully at just what
"available" means. There is a lot of hype in electric propulsion, and in
recent years it has been particularly visible in electric propulsion for
small spacecraft. *Many* of those systems are nowhere near ready for
flight, despite the gushing hype surrounding a lot of them.
One good question to ask is, what's the working life of the thruster?
And then you listen hard for words like "predicted" and "extrapolated" and
"target", as opposed to "tested" and "demonstrated".
Another is, what's the mass of the thruster *including* power electronics
and feed system? And then listen for phrases like "when we get around to
building flight-weight ones, we hope they'll weigh no more than...".
Henry
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