calius@SU-STAR.ARPA (Emilio Calius) (12/02/85)
I think that most everybody agrees that the effort required to carry
the ET to LEO is fairly trivial. Why hasn't it been done? I don't know, but I
can't help thinking that somebody in NASA made a political decision.
However, once you've got it in orbit, there are several issues to be
resolved:
1) How much does the Shuttle orbit change from one mission to the next?
That will determine how much delta V is required to assemble several tanks in
to a space station, a tank farm, a scrap yard, or whatever you have in mind.
Would 1 or 2 dedicated missions be sufficient for this purpose or do we have to
wait for the OMV?.
Note that big Coke can is a navigational hazard and also should have a limited
lifetime in the low orbits where it's likely to end up. How do we avoid a repeat
of the Skylab circus?
2) Once you've got them where you want them, there remains the question
of adapting them for whatever purpose you have in mind. This is likely to
require a fair amount of 0g shop work in which the US seems to be lagging behind
the USSR. For example, if you want to convert the tank into workshop/hangar
space, you will have to add a lot of local strengthening to the basic pressure
vessel structure, as well as adding all the services you require (electricity,
air, fluids, thermal control, etc.), airlocks (if you are making a hangar, you
have to figure out how to make one end into a door), and installing and checking
out your equipment. Contrast this with sending up space station modules pre-
configured and checked out on the ground. Even if you just want to use the tank
as a tank you will have to figure out how to modify it so that you can fill &
empty it in 0g (remember that its present plumbing is designed to be used once,
at longitudinal accelerations >= 1g).
3) If you're going to have humans routinely working inside in a "shirt-
sleeve" environment for longer than a few days, I am not sure wether the single
skin design of the ET is acceptable without some sort of escape mechanism. I
would feel much more confortable with a second skin and a self-sealing medium
in between. So maybe you have to coat the tank with some kind of foam and add
a shield or "bumper".
Maybe all of the above issues have already been resolved. If that is so
I would like to hear about it. Anyway, I still think that throwing away the ET
and its residual fuel is still a waste of a potentially very useful resource.
Just think of the residual contents of the tanks and refuelling the orbit
control systems of satellites as well as the OMV.
Emilio P. Calius
Dept. of Aero/Astro
Stanford Univ.
------henry@utzoo.UUCP (Henry Spencer) (12/03/85)
> ...[fitting out a tank as a space station means] installing and checking > out your equipment. Contrast this with sending up space station modules pre- > configured and checked out on the ground. Don't forget that checking things out on the ground means major expenses in "system integration" to make sure that things will stay in that state throughout launch. I believe the "Leasecraft" commercial platform project concluded that it was simpler and cheaper, overall, to plug the thing together in orbit, rather than doing it on the ground and then having to make very, very sure that it would stay plugged together through a rough and noisy launch. -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,linus,decvax}!utzoo!henry
peterb@pbear.UUCP (12/06/85)
[cannonfodder for the line eater] Actually I think many people are missing the point... IF construction is to occur in space, then some raw materials have to be present. I think it would not cost that much MORE to take the tanks all the way to orbit, and LEAVE them there. Then bring up the parts that have wiring, ventalation, etc, and live in the shuttle while transforming an external tank into a larger quarters. Hook the LS/CR (Life Support/Comminications & Research) section onto the external tank at one end and pump the free O2 in that tank to a container tank. Then crank up the LS unit and ramble inside. It should handle the stress of a low pressure atmosphere without much modification. Then with each launch, haul and adapt another external tank for more space. Peter Barada ihnp4!ima!pbear!peterb
john@frog.UUCP (John Woods, Software) (12/10/85)
> IF construction is to occur in space, then some raw materials have to > be present. I think it would not cost that much MORE to take the tanks all > the way to orbit, and LEAVE them there. The way I understand it (from L5 people who suggested it to NASA), the NASA engineers who looked at the idea said it cost but a pittance extra to boost them to orbit, and was overall a tremendous idea -- which they couldn't possibly justify to the bean counters. Advance science -- kill an accountant today! -- John Woods, Charles River Data Systems, Framingham MA, (617) 626-1101 ...!decvax!frog!john, ...!mit-eddie!jfw, jfw%mit-ccc@MIT-XX.ARPA Out of my way, I'm a scientist! War of the Worlds