alb@alice.UUCP (Adam L. Buchsbaum) (07/13/85)
The Challenger's launch attempt was aborted today, just three seconds before SRB ignition. In a near replay of the abort last summer, a valve that regulates the flow of hydrogen into the Number 2 Engine did not respond to its primary control circuit. A backup circuit sent the proper command 40 milliseconds after the failure was detected, but by that time, the ground sequence computer decided to abort the launch -- NASA rules forbid a launch unless all systems, including redundancies, are functioning, so that backups will be available once in flight. At the time of the abort, two engines were at full power, while the Number 2 Engine was near it. A water spray system, installed after last summer's abort and proceeding fire, activated, but there was no fire. NASA said the launch will be delayed at least 7 to 10 days while an assessment of the problem is made.
jg@mit-eddie.UUCP (Jim Gettys) (07/14/85)
I was at JSC for the attempted launch of Spacelab 2 Friday. (I worked on the Infrared Telescope that will fly on it five years ago...). The word was in a meeting to discuss the impact on various experiments on SL2 that another attempt would be no earlier than July 30. This was given as a "first guess" rather than as gospel; meetings yesterday were to firm up the estimate. This would put launch at full moon, which is the least desirable time for two or three experiments on board. Any slip beyond this date will again improve the situation. The concensus of all of the experimenters was to "go" as soon as Challenger is ready, even if it hurts some of the experiments. A good reason for this feeling is the effort required to get every thing ready for flight is large, and the longer the payload sits, the more trouble people will have with their experiments. There are more and more things which must be serviced the longer the payload sits on the ground. This delay should allow the repair of experiment 13 (Super Fluid Helium), which had a vacuum pump failure a couple days before the launch attempt. This failure caused some pump oil to be spilled in the payload bay. This caused KSC to have to turn off the pump, allowing the LHe to go normal, which would have cause at least half of the helium to be lost when reconverted on orbit (if successful...). Jim Gettys Project Athena jg@mit-athena.arpa