How complicated is too complicated? After 30 years of the Shuttle program, many of its flight-critical systems are still only marginally understood:
During the STS mission in November, a hydrogen pressurization control poppet cracked, and released a small fragment of metal into a critical pressurization line. There are several potentially catastrophic scenarios for a failure of this kind, including puncturing the line or failure of LH2 tank pressure control. They’re talking about pieces of metal dinging around in the line at speeds from 200-600 mph. Nobody seems sure whether the breakage occurred due to an existing undetected crack, or the crack occurred during the ascent.
Meanwhile, Discovery’s next flight is off the calendar pending a decision about how to evaluate existing valves, and possibly redesign them to avoid the problem.
[Finding something mean to say about the political situation in the U.S. is like shooting the proverbial fish in a barrel (as thoroughly evaluated by the Myth Busters). I’m just going to have to find someone else to talk about for a while.]