NASA underestimated Shuttle dangers

Discussion in 'Science and Technology' started by American Horse, Mar 7, 2011.

  1. American Horse

    American Horse AKA "Mustang"

    Jan 23, 2009
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    Now that we are down to the last trip for each for our Shuttles, with Discovery about to return from ISS, and only Endeavor (April 19) and Atlantis (June 28) each with one mission each left to fly, it would be worth considering the risks we took with the shuttle. NASA says they seriously underestimated the dangers astronauts faced when the shuttle fleet began flying in the early 1980s.

    A new internal safety study shows ... At the time, managers thought there was only a 1-in-100,000 chance of losing a shuttle and its crew. Engineers thought the probability was closer to 1 in 100. But in reality, the odds of a disaster were much higher.

    On each of the shuttle's first nine missions, there was a 1 in 9 chance of a catastrophic accident, according to the new risk analysis. On the next 16 flights that led up to and included the January 1986 Challenger disaster, the odds were 1 in 10. ...

    Consider this: There was only a 6 percent chance that NASA would fly its first 25 shuttle missions without losing an astronaut crew, the assessment shows.

    Moreover, on the 88 shuttle missions flown between the Challenger and Columbia accidents, there was only a 7 percent chance disaster would be averted. ...

    "It's useful for upcoming programs to understand that maybe their risk is higher than what they think it is," said Teri Hamlin, the NASA safety expert who led the study. ...

    "Obviously, ascent debris was one of those. It was a much-underappreciated risk," Hamlin said.

    Risk can increase if managers trade safety margin for increased vehicle performance, or as a result of external events.

    Case in point: an Environmental Protection Agency ban on freon
    NASA for years used CFC-11 freon as a blowing agent during the application of foam insulation on the shuttle's external tank. The ban forced NASA to develop and use an alternative.
    But initially, foam applied with the new environmentally friendly agent did not adhere well to the tank. The amount of foam shed in flight -- and resulting damage to the shuttle's vulnerable heat shield -- increased significantly.

    Consequently, the odds of disaster on nine flights in the late 1990s after the new agent went into use jumped from 1 in 38 to 1 in 21, the analysis shows.

    'We were lucky': NASA | FLORIDA TODAY |
    Last edited: Mar 7, 2011

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