[AR] Re: [AR] Re: [AR] Re: [AR] Re: “Transitioning space propulsion to a nitrous-based industry standard”
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Tue, 4 Apr 2023 19:46:16 -0400 (EDT)
On Tue, 4 Apr 2023, Matthew JL wrote:
Why not hydrogen peroxide in monoprop...
For one thing, like most monopropellants, monoprop peroxide gets you into
the various hassles of catalyst packs. (Silver screens work well for 85%
peroxide, but go much above that concentration and they'll melt; catalysts
for 100% peroxide aren't a fully solved problem.)
For long-term in-space use, e.g. in spacecraft orbit control, there is a
bigger headache: peroxide does decompose slowly in storage. Careful
choice of materials and thorough cleaning can get the rate down low enough
that the loss of strength in the peroxide is not a serious issue -- there
have been satellites with peroxide propulsion systems. Trouble is, that
slow decomposition releases oxygen gas, and that causes pressure buildup
in the tanks, and *that's* still serious enough that you can't just live
with it. So the tanks have to be vented occasionally, and in microgravity
it's rather difficult to separate gas and liquid well enough to vent just
the gas. (Unless the satellite is spin-stabilized, in which case careful
design can have centrifugal force do the separation for you. The earliest
Syncom satellites -- the first spin-stabilized GSO comsats -- had peroxide
propulsion.)
And there is considerable superstition about peroxide, partly based on
early German and US difficulties with (in hindsight) impure peroxide.
Which leads to distrust and suspicion of it, and that can be an obstacle
for (e.g.) convincing launcher operators that your peroxide-propelled
satellite should be allowed on their precious rocket.
Henry
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