After a careful analysis of the risks, NASA is betting that the chances of catastrophe when the damaged space shuttle Endeavour returns to Earth on Aug. 22 are zero. If this were the NASA of old — the one that disastrously miscalculated the dangers of a leaky O-ring and a punctured heat shield to the Challenger and Columbia shuttles, respectively — you would surely have heard a round of protest from at least a few highly qualified aerospace engineers.
But in making the decision Thursday night to fly Endeavour home as-is, skipping an untested-in-space repair job to the gouge on the shuttle's belly, NASA seems to have won the confidence of the whole shuttle engineering community. John Shannon, chairman of the Endeavour mission management team and the man who assessed the risk, made the call based on an abundance of testing and analysis over the past week, rather than from any rocket jockey arrogance, which was largely blamed for the last two shuttle losses. Among the 30 organizations from which scientists were called in for independent analyses: Ames Research Center; Langley Research Center; the White Sands Test Facility; and the Johnson, Kennedy and Marshall space centers. And, of course, there was input from NASA headquarters.
Why the exhaustive deliberations? Because the stakes are high — the potential loss of life above all — for the future of the space shuttle program, which impacts, among other things, the maintenance of the Hubble Telescope and the International Space Station, which can't survive without a space truck capable of delivering heavy construction loads. The investigation's thoroughness is also a direct result of an overhaul of NASA policies following the 2003 Columbia disaster. Asked whether the agency may have gone too far this time in information overload, Shannon, who never broke a sweat making his announcement in a press briefing, said no: "I love it. It's outstanding."
Shannon spent five hours with a team of about 200 engineers and mission management folks going over the data on Endeavour's gouge, caused by the seemingly unstoppable shedding of foam insulation off the external fuel tank during launch. The gouge was determined to be of a size and in a location that would not create danger to the crew or ship. Shannon says the vote was not unanimous but "pretty overwhelming" for Endeavour to return home without repair.
The lone holdout was the Johnson Space Center engineering group, which, according to Shannon, agreed that flying as-is was acceptable but considered it "prudent" to try to patch the hole to increase safety margins and decrease the risk of further damage to the shuttle on re-entry. But Shannon says he's more comfortable with the known risks associated with the gouge than with the unknown risks of an untried repair job, which would have required the astronauts to coat damaged tiles with heat-resistant paint and fill the hole with a caulk-like goo. The next shuttle mission, Shannon said, will likely include an in-space test of repair options, so mission managers can better understand what they're facing.
With the gouge issue off the radar for now, NASA turned its attention to the next blip on the screen: Hurricane Dean, now pounding the islands of the Caribbean and drag-racing Endeavour toward the Gulf — right under the shuttle's landing-day flight path.