[AR] big rockets (was Re: Nothing to do with rockets.)
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Mon, 4 Oct 2021 19:24:34 -0400 (EDT)
On Mon, 4 Oct 2021, John Stoffel wrote:
It might also be a vehicle for large things that people can't launch
even now without major contortions, here's looking at you JWST! Just
imagine how good a telescope you could send up if you didn't have to
pack it into an A5 fairing. Or what about those SAR satellites with
big radar dishes?
Although note, the issue here is not so much that the cargo volumes aren't
big enough, as that in-orbit assembly is not available -- something that
could be corrected without a great big rocket.
Nowadays, even ground observatories invariably build their big telescopes
with multi-segment mirrors.
The absolute poster child for why to avoid compact packages which deploy
themselves in space was the Galileo Jupiter orbiter... but note that it
was designed to deploy its antenna *before* being released from the
Shuttle, when corrective attention (or even "no, it's broken, bring it
back down and we'll fix it") was still possible. Compare to what happened
when Compton had an antenna-deployment problem (of a different kind):
release was delayed, the crew went out and fixed it, back on track,
mission successful. But alas for Galileo, its original upper stage got
canceled, the mission plan had to be changed so that everything would
still fit in one launch, and antenna deployment had to be postponed until
way out in deep space... where there was nothing to be done when the
antenna hung up and didn't deploy.
When you can build bigger things and just throw mass at the problem, it
would seem to help reduce the problem space, or at least change it.
Broadly true, but remember that bigger things don't necessarily have to be
launched in one piece. As you yourself note:
Looking at how they ship those huge ring cranes in standard shipping
container sized pieces...
Trust me, the spacecraft people would be *delighted* to do their final
assembly and checkout after the noisy bouncy part was over -- that would
be a much better approach, strongly preferred. Doesn't really matter
whether bringing the subassemblies up requires multiple loads, so long as
they all end up in the same place, where a couple of guys can plug them
together, check them out, and see them off.
Henry
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