This new study blows down that assumption:
Steve Poulos, a top shuttle official, acknowledges there is "a debate" inside the agency about the threat posed by space debris. One school of thought is that a fatal debris strike is "probable," Poulos says. But he says others think such an event is likely to be "infrequent."
Let's cut the crap for a moment here. This is all gut instinct from Engineers at NASA. Some think it's a serious issue, others don't. The real problem here ain't the debris - we can never eliminate debris or vibrations for that matter. The real problem is the tiles themselves. Their design is the issue, everything else they're doing is just an attempt to patch up a design flaw.
In February 2003, the shuttle Columbia broke apart when a piece of foam fell from the fuel tank and opened a 6- to 8-inch-wide hole in the front edge of the left wing. As Columbia returned to Earth, hot gases entered the hole, causing the shuttle to disintegrate.
I love how they still talk as if that was the God given truth. The truth is no one can know really what caused the tiles on that left wing to fall off to open that hole. The best guess is ice debris, but then why is NASA spending so much time identifying and eliminating or minizing hundreds of other sources of debris? It's nice spin, but the truth is no one knows jack.
Space debris, including bits of rock, pieces of old satellites and other trash, often ding the shuttle as it circles the Earth but usually causes no serious harm. Before Columbia, NASA estimated the spacecraft stood a 1-in-500 chance of being destroyed by space debris. That's well below the shuttle program's goal of a 1-in-200 chance.
But the preliminary analysis dated April 26 placed the odds that orbital debris could destroy the next shuttle at a range from 1 in 54 to 1 in 113. That risk estimate stems from recent tests showing that the space shuttle's heat shield is more fragile than NASA had realized.
The analysis was obtained by USA TODAY from a NASA staffer who declined to be identified because this person is not authorized to release such documents.
The analysis done by the staffer is based on the assumption that the tiles can't withstand even a pinhole of exposure. That is the main reason for the difference in results. NASA must have serious problems if this staffer/engineer felt ignored enough in his concerns to release this to the press. Poor bugger.
Tests show that the shuttle can survive scrapes up to 0.1 inch inflicted by space debris to the front of the wing, Poulos says. He points out that orbital debris has smacked the front of the wings 42 times and did significant damage once.
The target was a 1 in 200 chance. If the actual chance turns out to be 1 in 42 that is a significant design buster. And hence comes a big problem with NASA: inability to design safely. Produce some pretty numbers that show we're good to go, and nobody questions.
And this story proves it:
Meanwhile, shuttle managers have decided against a third fueling test. The test, which would have added several days to the amount of work necessary at the launch pad, is no longer necessary because NASA believes it has enough information from previous tests to identify and fix the cause of the problematic fuel valve.
The first fueling test failed because the sensors used to detect fuel levels in the tank were misreporting actual levels. If the Shuttle's engines continue to burn as the fuel supply runs out the consequences could be disastrous. The belief was that the problem was caused by the tank they were using. However some were concerned that the new heaters that had been installed to prevent ice build ups on the tank were interfering somehow with the sensors. The idea was hook it up to a new tank and test and see if the problem remains. I bet that satisfied the naysayers.
Apparently the idea got turfed because it would have meant to much extra work. I wouldn't want to be the astronauts on that next flight.
I don't think there will be a next flight. No amount of duct tape will make the shuttle a good design; every fix they attempt turns up more problems. I think the shuttle fleet has flown its last.
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