alb@alice.UUCP (Adam L. Buchsbaum) (04/12/84)
OK, this is an all encompassing answer to all the fuel questions. 1) Nelson's MMU did ''red-line'' on fuel. That is why he broke off the SMM stabilization attempt and flew back to the shuttle. 2) There was another, fully-fueled MMU on board. 3) The MMU's can be refueled in orbit in about 20 minutes. 4) The shuttle itself ran low on maneuvering fuel, due to numerous attempts to grab SMM with the RMS while the satellite was wobbling and tumbling. The fuel reserves for the front steering jets dropped to about 21 percent. This is why no further MMU-propelled EVA was executed; there may not have been enough shuttle fuel left to pick up the astronaut if his MMU failed. 5) There was no danger to reentry due to the low fuel reserve on the shuttle. 6) It was decided that there was enough shuttle maneuvering fuel (nitrogen tetroxide and monomethyl hydrazine, for those who are wondering) to attempt another grab at the SMM once it was stabilized (but still spinning). As an aside, the additional maneuvers performed Tuesday in which the snare was successful burned up only half the fuel that ground controllers thought they would. That should answer any and all questions. If I missed any, let me know.
ralph@inuxc.UUCP (Ralph Keyser) (04/13/84)
A couple of additional points: 1) The "red-line" on the MMU was pretty high. Nelson had just under 50% of his fuel remaining when he returned to the shuttle. 2) The shuttle is the second backup in the event of an MMU failure. If an astronaut has an MMU failure, then either the shuttle itself or another crew member in the second MMU would go for the rescue. Because the shuttle was low on fuel (down to 21% in the forward RCS) [See Adam's article for more details], the second MMU was tested inside the cargo bay only. Ox did the flying on that one. CNN provides much better coverage of inflight events than the networks. They were very clear about the entire fuel issue and what it meant to the mission. Ralph Keyser ihnp4!inuxc!ralph