This article details a number of ongoing safety issues surrounding the space shuttle. It’s long and ugly. Among them are
Entire banks of the orbiter’s 44 jet thrusters, needed for precise maneuvers in space, must be shut off because of various malfunctions during most flights. In 1995, damaged thrusters aboard Discovery spewed hazardous fuel as it approached the Mir space station, much to the alarm of the Russians inside.
Electric arcing from damaged wire caused a shutdown of computers that controlled two of three main engines aboard Columbia in 1999. A backup system took over. But despite subsequent studies suggesting damage and deterioration of aging wiring, not all of it has been replaced.
NASA has been unable to prevent episodes of highly explosive hydrogen gas — which leaks from the external tank, shuttle and ground systems — accumulating beneath the shuttle as it sits on the launchpad. High concentrations of the gas have prompted several scrubbed launches.
I’d think that the last of these should be relatively easy (compared to the others) because it is a launchpad issue that can be dealt with on the ground as it’s happening. But no luck so far.
NASA says that the thruster failures have happened 117 times on 84 flights. Excuse me, but isn’t that a significant percentage? Another problem, this one surrounding the auxiliary power units, has occurred 170 times on 75 missions. On one Columbia mission, two of the APUs caught fire
resulting in internal “detonation” and “minor shrapnel damage.”
Huh? “Minor”? “Shrapnel damage”? On a space shuttle?
Maybe I’m just overly critical of a system that I’m not overly fond of. Maybe I’m just bitter because all the things I hoped for as a kid haven’t materialized. I do realize how complex and inherently dangerous space flight is. But I think NASA has used up all of it’s benefit of the doubt when it comes to safety issues on the space shuttle.
The link has more details of these issues and more.