[AR] Re: DARPA responsive launch challenge
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Sun, 22 Apr 2018 23:32:00 -0400 (EDT)
On Sun, 22 Apr 2018, Henry Vanderbilt wrote:
...stabilized atomic hydrogen (just how it's stabilized is, of course,
never explained)...
Mind, given the stabilization is SFnal handwaving, you could assume it's
*stable*. IE, not prone to detonating if looked at cross-eyed, and
comes out of the reactor still monatomic.
I fear I don't believe it, at least not unless we do some cross-genre
borrowing and get Harry Potter involved. :-) No conceivable molecular
bonding is going to stay 100% intact under NTR conditions, and with this
stuff, 99% is not good enough. I think it would take new physics, not
just new chemistry, and the new physics would probably be good for enough
other things that atomic hydrogen would take a back seat quickly.
(Without that, I don't say it's definitely impossible, but that's the way
I'd bet.)
But if we're going for SFnal high-energy monoprops, I'd prefer metallic
hydrogen to monatomic. The storage density on single-H must be truly
abysmally low...
Very probably. I don't think anybody's ever had enough of it all together
for long enough to get an idea of what its liquid density would be, but
pretty low seems like a good guess.
There was a brief surge of interest in this and other "free radical"
propellants at one point in the 50s, and that may be where Heinlein got
the idea. Toward the end of that, as reality started to set in, the
concepts were things like modest percentages of H frozen in solid
hydrogen, perhaps in a slurry in liquid helium, perhaps in a strong
magnetic field. Which might make it a bit less impossible to preserve the
stuff, but would also reduce performance to the point that it's quite
likely not worth it.
Metallic hydrogen (or Bob Forward's metastable helium), if it's stable at
reasonable pressures once made, does seem more appealing.
Henry
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