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Shuttle Launch Delayed Again, Possibly Until December
An anonymous reader writes "NASA engineers worked overnight trying to fix the electrical problem that forced the launch of space shuttle Discovery to be delayed again. Mission managers will meet later Wednesday to figure out if a launch on Thursday is even possible. The tentative plan is to have Discovery lift off Thursday at 3:29pm. If that does not happen it would be rescheduled for Sunday. If it cannot launch Sunday then it will have to wait until December. NASA engineers have a lot of work on their hands Wednesday morning. Discovery has an electrical issue that forced officials to postpone its liftoff, which had been rescheduled for Wednesday afternoon."
Did they check if it's plugged in?
Have they tried turning it off and on?
This article contains some more specifics regarding the problem. Apparently one of the main engine controller computers (the computers that regulate main engine gimbaling and throttle control) failed to power up properly. There was a short time period where a low-voltage occurred which flagged a boot-up sequence issue. Engineers are trying to figure out what caused the voltage drop and, thus, triggered the error in the processor initialization. More information regarding the SSME controllers can be found here.
Apparently the breaker that controls the processor was cycled five times over night. Engineers are guessing that the cycling caused some funny transient anomalies in the circuit which caused the fault. Despite the fault, the main events controller for the shuttle system was brought to full power and is operating nominally, so it's not like the whole computer is crap. NASA just wants to be sure that, a) the fault was actually caused by the breaker cycling and b) the fault won't cause further glitches in any of the other controller systems on the shuttle.
Interesting stuff indeed. It's probably a good thing that NASA is demanding certainty from it's engineers before clearing Discovery for launch.
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To be fair, if the Buran design is superior it's likely because they started with the shuttle design and improved on it, whereas the shuttle was designed from the ground up. The Russians were (and are) clearly very good at designing space vehicles, but it's a lot easier to come up with a better design if you start with the design your opponent already came up with.