Learning From The Challenger and Columbia Disasters

Friday, the 28th of January is the 25th anniversary of the Space Shuttle Challenger disaster. Hard to believe it was that long ago. As I’ve been watching the recent developments with the shuttle Discovery (STS-133), with the series of delays due to faulty valves early on and then the discovery of numerous cracked stringers in the external fuel tank, it’s got me wondering if we are seeing a repeat of the same mentality that caused the disasters with Challenger in 1986 and Columbia in 2003.

The O-ring problem on the solid rocket boosters that doomed Challenger first occurred on STS-2, the second flight of the shuttle Columbia that occurred on November 12, 1981. The problem was looked at by Thiokol, the company that designed the boosters, and they did some testing at elevated stress levels that turned up nothing, so it was written off as an anomaly. But, for the 15 shuttle launches that occurred between 1984 and the Challenger accident, all but three showed O-ring damage. It had not caused a problem up to that point and this deviation was normalized as routine—until January 28, 1986. The Challenger crew paid the cost of that behavior with their lives.

The same normalization of deviations applied to the foam and ice coming off the large external fuel tank that frequently pelted the shuttles, damaging their delicate ceramic tiles that form the heat shield for the vehicle. Foam falls off all the time, but it never caused a problem, so it must be okay to keep launching. February 1, 2003 proved that to be wrong when Columbia (STS-107) reentered the atmosphere with a hole in a leading edge carbon-carbon panel of the left wing, which allowed super-hot gases to destroy the structural integrity of the wing and the break up of the shuttle. Another crew paid the ultimate price for NASA accepting the abnormal as normal.

Today we are looking at the final launch of Discovery sometime towards the end of February 2011, postponed from the initial launch date back in November 2010. Did we get lucky this time? Could these cracked stringers in the main fuel tank have caused a failure of the tank as the shuttle raced into orbit? Equally important; is this a problem that has been there all along and it’s been accepted as the norm? I don’t know. I do know that I’m glad they found it and that repairs are under way to fix the problem. Hopefully we will see another successful mission for Discovery at the end of February. With the end of the shuttle program looming ever closer, NASA needs to be even more vigilant to ensure that the final missions launch and land without any problems.

If you want a nitty-gritty view of NASA from the inside, check out Mike Mullane’s book Riding Rockets. It gives you a peak behind the golden curtain NASA puts up for the general public. Very interesting.

Till next time,

RC Davison

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