Posted on 02/06/2003 9:45:33 AM PST by Zavien Doombringer
NASA investigators want to know if adjustments made to the position of the space shuttle Columbia during its last minutes by the vehicle's onboard control computers could have played a role in its breakup during re-entry Feb. 1. In a revised timeline of events released Feb. 3, Ron Dittemore, NASA's space shuttle program manager, said that at 8:59 a.m. EST, Columbia's five onboard computer systems began to detect a significant increase in drag on the vehicle's left wing and ordered two of the shuttle's four yaw jets to fire for 1.5 seconds to compensate for the change.
Investigators aren't sure yet whether the adjustments ordered by the computer played a role in the shuttle's breakup. "It was well within the flight control system's capability to handle the [maneuver]," said Dittemore. "But what is becoming interesting to us now is the rate of change."
While Dittemore acknowledged that NASA may never be able to determine the exact root cause of the crash, he said investigators are now studying all of the data from the launch process as well as the shuttle's flight control systems.
The focus on Columbia's flight control systems could be significant. On Feb. 3, Computerworld reported that Columbia and other space shuttles have a history of computer glitches that have been linked to control systems, including left-wing steering controls (see story).
Although officials said it's too early in the investigation to pin the blame for the crash on the control computers, William Readdy, deputy administrator of NASA, said officials are actively searching for any of the shuttle's five onboard computer systems. Although it's unlikely they survived the crash, he said, the computers have "memory resident in them" that could shed light on the status of the shuttle after communications were lost with ground control.
Each computer's memory stores "telemetry of thousands of parameters that affect the flight of the shuttle," Readdy said.
Columbia and other space shuttles have experienced a series of control computer failures during the past two decades, including one that had a direct link to the spacecraft's left-wing control systems. During a March 1996 return flight, NASA officials discovered a computer circuit problem that controlled steering hardware on Columbia's left wing. The computer circuit was responsible for controlling the spacecraft's left rudder, flaps and other critical landing functions.
Speaking at a news conference prior to Columbia's landing in March 1996, NASA spokesman Rob Navius downplayed the seriousness of the computer problem.
"There are three additional paths of data that are up and running in perfect shape, and there's multiple redundancy that would permit a safe landing," he said. Although Columbia landed without incident that time, NASA officials said the failure was significant enough that had it happened earlier in the flight, the agency would likely have ordered the shuttle home early.
The General Accounting Office, the investigative arm of Congress, has also criticized NASA in the past for relying on the same commercial contractors to develop, test and validate the space shuttle software (see story).
However, Donna Shirley, the former manager of NASA's Mars Exploration Program and the team that built the Sojourner Microrover, said there is no evidence yet that flaws in NASA's software-validation program had anything to do with the disaster.
Remember the shuttle is also going 1500 mph. It is the delta velocity between the debris and shuttle that is important. Delta velocity is pretty low that is why NASA discounted this as a problem.
BUMP
It's been many, many moons since I had control systems class, but any professional control system would be damped enough to prevent it from overshooting the target (ie. overcompensating and causing a spin to the right). I think that what he's hinting at here is that the rate of change to the left couldn't be handled by the control system and that the shuttle spun to the left. Probably because the controls on the left were comprimised.
Yes, and the larger the object, the slower it would have accelerated.
1500 mph!?! Back that up with a shred of evidence. Maybe you're someone who never took a basic physics course in 8th grade, or if you did you weren't listening.
The debris (whatever it was) fell off the top of the main fuel tank. That fuel tank may have been travelling at 1500 mph, but so was the debris, and so was the shuttle strapped to the tank.
Upon impacting the wing, the debris would have had a relative velocity equal to how much it slowed since falling, plus however much the shuttle itself accellerated in the time it took the debris to go from the top of the fuel tank to the wing.
You are suggesting that the debris decellerated to 0 mph so the shuttle wing could hit it at a full 1500 mph? Or perhaps you suggest that in that fraction of a second, the orbiter and the attached fuel tank accellerated an extra, say 1000 mph, to meet the decelerating debris at 1500mph?
http://www.computerworld.com/securitytopics/security/recovery/story/0,10801,78201,00.html
Link to the related article mentioned:
I have been out of the loop, so to speak, on processor control since my days with Allen Bradley and Honeywell.
I am sure the new stuff is much better than the old days.
Also, the after shot with the low res cam did not show any damage at all. If it were major damage the white exposed tiles would have shown on the image.
okay, i wasn't imagining things yesterday... i was time traveling :o)
Rest in peace for the crew of STS-107
Time to start implementing a new space delivery system other than the shuttle which is coined in NASA as the "Flying Brick".
Phase out the old and bring in the new.
The truth is somewhere in between. The chunk fell off because it has been grabbed by the tremendous drag pressure of that 1500 mph slip stream. By the time it hits the wing, it hasn't gained the full relative velocity to the spacecraft that the slipstream has, but it's got about 500 mph worth. That's still a fair energy even for a chunk of foam.
Didn't see this before I posted. You got it.
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