The idea is true, but it would be wrong to let it hang unexamined. One hundred and thirteen times we have sent a shuttle into space. Twice we’ve seen catastrophic failures and the loss of all hands. How do those odds sound?
They sound just about like what you would expect, based on the history of rocketry. As described by Theodore Postol, professor of science, technology and national-defense policy at the Massachusetts Institute of Technology, even the most reliable space vehicle systems (booster rockets) have roughly a 2 percent failure rate. At that rate, if the shuttles continue to fly five missions annually, then we should expect to see a Columbia or Challenger disaster every decade.
NASA’s stated estimates of the risk of failure for any given mission are one in 145, or 0.7 percent, and its engineers and scientists strive constantly and heroically to make it zero. Still, the sheer numbers of shuttle flights work against them. (Columbia alone saw space 28 times.) Assuming that NASA’s 0.7-percent-per-mission risk estimate is correct, then over 113 missions the likelihood that one shuttle will be destroyed reaches about 65 percent.
No one may know with certainty how best to calculate the odds against the shuttles because risk determination can be such a complex and uncertain science. One finds little reason for confidence that the number could have been much lower when reviewing the shuttle program’s history.
For all that the shuttle can be saluted as an engineering marvel, it is also the spacegoing equivalent of a camel--a committee’s attempt to build a horse. When conceived in the late 1960s, the shuttle was to be a modest reusable craft for inexpensively delivering small crews to a space station and returning them. Shuttle and station were supposed to be stepping-stones to Mars. That original space station project was scuttled, but the shuttle survived, with a less defined purpose. New missions were soon found for it, however. Researchers wanted the capability to perform more experiments in orbit, so room for those was added. Using the shuttle to launch commercial satellites looked like a source of revenue. The Pentagon wanted the craft to carry military satellites, and so the cargo bay was enlarged further.
"Mission creep" gradually transfigured the shuttle, enlarging its cargo bay and morphing the coupe into a pickup truck. The engineering consequences were not minor. Building a reusable craft also proved more difficult than anticipated.
None of this history or the estimates of calamity are obscure; if anything, they littered the media back during the early years of the shuttle program and immediately after the Challenger explosion. The Challenger, of course, was felled by faulty O-rings, and physicist Richard Feynman and the Rogers Commission that investigated the crash argued successfully that this flaw was the result of bad planning and inadequate oversight built into the program. Problem identified, fix applied, and the shuttle program was far safer for it. Still, an unintended consequence of the defective O-ring discovery may have been to distract the public from the fact that, beyond problems of error or incompetence, the shuttle’s jack-of-all-trades design and operational profile pose fundamental safety problems that virtually guarantee eventual disasters.
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More in the article should you care to read. - LRK -
he shuttles were to have been museum pieces by now.
