bill@sigma.UUCP (William Swan) (11/29/85)
In article <275@kovacs.UUCP> rivero@kovacs.UUCP (Michael Foster Rivero) writes: >[...] As an aside, if the external shuttle tanks were re-designed > to ride all the way to orbit, they might make great > pressurized bulk storage units that could be attached to a > space station framework. [...] With > shuttles going up on a once a month basis during SDI, you > would have a LOT of pressurized space at the end of every > year. (I just subscribed to this group, apologies if this is old ground...) I worked on the Shuttle project from '72 to '75. I seem to recall that they were planning on carrying the external tank into orbit, the idea being exactly as Mr. Rivero proposed, to create a Space Station out of the expended tanks. Has this changed? Do they drop it before (final) orbit now? -- William Swan {ihnp4,decvax,allegra,...}!uw-beaver!tikal!sigma!bill
dietz@SLB-DOLL.CSNET (Paul Dietz) (12/01/85)
Currently, the shuttle is maneuvered so the ET drops into the Indian Ocean (or the Pacific on some launch paths). As I understand it, detailed studies by NASA have shown that it's not simple to turn an external tank into a space station. A space station is just too complicated (with wiring, electronics, temperature control & ventilation, etc.) to make in orbit at this time (except by simple assembly of prefab modules). A near-term use of ET's is as reaction mass. The simplest way to do this, NASA has found, is to drop the ET on the end of a long tether below (or above) the shuttle, then release it. Unfortunately, any mass saving in OMS fuel is used up by the mass of the cable. This idea could be used, however, to boost a space station into higher orbits, since the cable could be left in orbit and used many times. ET's can't just be left in low orbit without processing, since they have a large cross section and experience considerable drag (as did Skylab). There are designs on the board for solar furnaces for melting ET's, turing each into a twelve foot solid aluminum sphere. If SDI ever comes to pass (which seems doubtful) a major problem will be shielding the electronics against cosmic rays and 14.7 MeV neutrons from thermonuclear weapons. The last are especially nasty; the only way to shield against them is by using lots of mass. Raw ET material would be good for this; one ET can be turned into a solid aluminum sphere twelve feet across.
henry@utzoo.UUCP (Henry Spencer) (12/03/85)
> As I understand it, detailed studies by NASA have shown that it's not > simple to turn an external tank into a space station. A space station > is just too complicated (with wiring, electronics, temperature control & > ventilation, etc.) to make in orbit at this time (except by simple > assembly of prefab modules). One possibility would be to revive the original Skylab "wet workshop" concept. Pre-install as much of the equipment as will stand being soaked in liquid hydrogen for a while. On reaching orbit, vent the tank to space for a while to clear out the hydrogen, and move in. This concept hit some snags during Skylab development, and was eventually abandoned, but Wernher von Braun (for one) thought that the "wet workshop" approach could have been made to work with a little more effort. When it became clear that there were going to be spare Saturn Vs around at the end of Apollo, the "dry workshop" alternative became feasible, and the incentive for solving the "wet workshop"'s problems went away. Some features of Skylab, like the metal-grid floors, were holdovers from the earlier concept. -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,linus,decvax}!utzoo!henry