kcarroll@utzoo.UUCP (Kieran A. Carroll) (12/06/85)
*
While it maight be insuperably difficult to
make a shuttle's external tank into a functioning
space station (requiring all sorts of extra thermal
control, attitude and orbit control, power supply
and conditioning equipment, etc.), I don't believe
that it'd be too difficult (or expensive) to carry
one into orbit to be a >>part<< of a space station.
Provided with (a) an airlock at the top,
(b) a hatch between the oxygen and hydrogen tanks, and
(c) a simple vent, for discarding LH2 and LO2 as they
vaporize, an ET could be attached almost immediately to
the habitable portion of an already-existing
space station. Extra thermal insulation might have to
be sprayed on the outside before launch, in order for the
ET not to become too cold (or hot!) on-orbit; this would
involve a mass penalty, as would the airlock, hatch and vent.
However, for the resulting >>small<< mass penalty
(maybe a total of 1 ton, or two?), a >>vast<< amount
of habitable volume would be added to the station!
While this volume would not initially contain any useful
equipment, I'm sure that uses would soon be found for it,
enormously off-setting the initial investment.
If nothing else, it could be used as a relaxation area by the
crew (who, after all, will be spending 3 months at a time
in a space the size of 5 house-trailers strung together).
It seems to me that the arguments against bringing the ETs
to orbit are based on the assumption that it'll have to
serve many functions at once, and that it'd be too expensive
to make it do that. If you don't make it perform any other function
than providing "attic space" for the station, tho',
it can be provided essentially for free (in fact, bringing it
up to orbit may allow the shuttle to >>increase<< its
to-orbit payload, since the fuel previously used in the
ET-jettison manoeuvre won't have to be expended, and this may
offset the mass penalty of the extra ET-attached hardware).
I think that by requiring too much performance of the ET
as a space station component, its cost can of course be forced
(literally) sky-high; the same is true of >>any<< part of
a spacecraft. Why not just bring up a few tanks empty,
at a very low cost, and find out what they're good for up there,
before adding performance requirements to them and raising their
cost? (These people are not only looking a gift horse in the
mouth, they're sending it back because with a rating of only
1 horsepower, it's makes a lousy sportscar....)
Any comments?
--
Kieran A. Carroll @ U of Toronto Aerospace Institute
{allegra,ihnp4,linus,decvax}!utzoo!kcarrollems@amdahl.UUCP (ems) (12/10/85)
> ... > If nothing else, it could be used as a relaxation area by the > crew (who, after all, will be spending 3 months at a time > in a space the size of 5 house-trailers strung together). Oh boy! 3D raquet ball in space! I actually spent 3.5 months in a space far smaller than 5 house-trailers in a NASA sponsored project. It was about 11 x 17 feet. There were three of us. No windows. No exit. It would be very handy to have a place to go just to be alone. An attic would be a great idea. Another possible use? Why not start a garden? There was a definite trend for dust, hair, etc. to build up in The Box (our name for the project...) The same should happen with the space station. Put a slow centifuge wheel in the tank, add dirt/dust, water, seeds, and electric light. (Maybe even some 'fertilizer'). Might not be much to you to see a flower or two, but there was a time when I would have found it to be a great pleasure to see something living, something from 'outside'... -- E. Michael Smith ...!{hplabs,ihnp4,amd,nsc}!amdahl!ems This is the obligatory disclaimer of everything.
wmartin@brl-tgr.ARPA (Will Martin ) (12/11/85)
I'm sure we can all agree that there may be difficulties in using shuttle External Tanks (ETs) in building a space station. However, I'm also sure that we can all agree that there MAY be a use for them later in the space station construction project. Some possibilities (general storage, air or fuel storage, garden space, privacy areas, etc.) have already been suggested on the net. In any case, right now we are taking them to a certain point, and then discarding them back to burn up in the atmosphere. To stop doing this may cost something in shuttle payloads, or save something in fuel usage (I've seen both views expressed here). I think the problem is that, if the ETs are taken up to LEO, and just left there, their orbits will decay relatively rapidly, and they will burn up and be lost anyway (plus we'll have the old "Skylab-is-falling" bad PR of space debris falling back in random locations). So, what will it cost (in terms of impact on current missions, development and implementation costs, etc.) to arrange for all future ETs to be carried up to LEO and then put into some higher "parking" orbit, where they can orbit eternally out of everyones' way until someone decides they want one? Thus they can be stored for eventual use if and when they are needed. I would think that this would be the best course. It keeps open the greatest possible number of options, and I would think that the incremental cost to do this would be roughly the cost of one PAM or equivalent per shuttle launch, plus some amortized engineering costs. This is trivial in comparison to the costs at some future time to boost into orbit enough raw material or prefab assemblies to create enclosed space equivalent to the volume of an ET. When the future space station operators need an ET-sized space, all they'll have to do is send up the inter-orbit transfer vehicle to the "parking lot" where the ETs are orbiting, and give one a shove in the right direction and time so that it sprials down to the station's orbit at a convenient moment. Minimal cost, no need to bother the groundhogs, etc. After all, mass in orbit is like money in the bank -- if you've got it there, you can always get it out, and it can be left indefinitely for future use, even if now you can't figure out what good it might be. If it is not there, it will cost you to get some in there. Why throw away what we already [almost] have by discarding ETs any longer? Up till now, shuttle flights have really been more like experiments than operations, so I can't fault NASA for not complicating things by trying to do this too. But, as shuttle flights become routine business, lets get this built in as a side benefit, as long as it can be done reasonably. Regards, Will Martin UUCP/USENET: seismo!brl-bmd!wmartin or ARPA/MILNET: wmartin@almsa-1.ARPA
ajs@hpfcla.UUCP (12/16/85)
> ...arrange for all future ETs to be carried up to LEO and then put into > some higher "parking" orbit... I agree, and offer this food for thought. How do you suppose the design work on the space station might be affected if at this moment we already had 20+ external tanks waiting for us in some parking orbit? I've heard rational arguments both for and against additional orbiter vehicles, even against having a space station (e.g. see this month's Scientific American). Given that we're already in the shuttle launching business, and the low incremental cost to save those ETs for future use, maybe the activists among us should focus on that as a safe, NON- CONTROVERSIAL short-term goal for NASA. Used to be a space station fanatic but now I'm not so sure... Alan Silverstein
mike@amdcad.UUCP (Mike Parker) (12/21/85)
In article <22000012@hpfcla.UUCP> ajs@hpfcla.UUCP writes: >I agree, and offer this food for thought. How do you suppose the design >work on the space station might be affected if at this moment we already >had 20+ external tanks waiting for us in some parking orbit? > I don't know how it would affect space station design, but if they went back to painting them white and tied all of them into a big bundle, it'd be a hell of a sight just after sunset. Mike
al@ames.UUCP (Al Globus) (12/31/85)
> * > While it maight be insuperably difficult to > make a shuttle's external tank into a functioning > space station (requiring all sorts of extra thermal > control, attitude and orbit control, power supply > and conditioning equipment, etc.), I don't believe > that it'd be too difficult (or expensive) to carry > one into orbit to be a >>part<< of a space station. > Provided with (a) an airlock at the top, > (b) a hatch between the oxygen and hydrogen tanks, and Taylor and Associates designed a aft compartment that sits at the end of the tank during launch. It is habitable and manned. When you get to orbit, you can work on the tank in a shirt sleeve environment. > (maybe a total of 1 ton, or two?), a >>vast<< amount > of habitable volume would be added to the station! > While this volume would not initially contain any useful > equipment, I'm sure that uses would soon be found for it, One use: televised sports. Another: a place for trash (a major problem on shuttle) Another: a source of raw materials for manufacture Another: a movie set for true 0-g space movies Another: mounting area for space exposure experiments Another: satellite repair hangers (possibly unpressurized
michaelm@3comvax.UUCP (Michael McNeil) (01/03/86)
In article <22000012@hpfcla.UUCP> ajs@hpfcla.UUCP writes: >I've heard rational arguments both for and against additional orbiter >vehicles, even against having a space station (e.g. see this month's >Scientific American). Given that we're already in the shuttle launching >business, and the low incremental cost to save those ETs for future use, >maybe the activists among us should focus on that as a safe, NON- >CONTROVERSIAL short-term goal for NASA. > >Used to be a space station fanatic but now I'm not so sure... >Alan Silverstein I doubt very much that this goal is actually noncontroversial, and I also suspect that if a noncontroversial goal for NASA could be found, that it, whatever it is, would not be worth doing. -- Michael McNeil 3Com Corporation "All disclaimers including this one apply" (415) 960-9367 ..!ucbvax!hplabs!oliveb!3comvax!michaelm But as in all businesses the acting part is most difficult, especially where the work of many agents must concur, so was it found in this. For some of those that should have gone in England fell off and would not go; other merchants and friends that had offered to adventure their moneys withdrew and pretended many excuses; some disliking they went not to Guiana; others again would adventure nothing except they went to Virginia. Some again (and those that were most relied on) fell in utter dislike with Virginia and would do nothing if they went thither. In the midst of these distractions, they of Leyden who had put off their estates and laid out their moneys were brought into a great strait, fearing what issue these things would come to. William Bradford, 1630, *Of Plimouth Plantation*, regarding events of Spring, 1620