By Jeremy Manier
HOUSTON - The space shuttle Discovery rolled to the launch pad on Wednesday, bringing NASA one step closer to its planned launch next month.
If Discovery takes off into space then, it will be the first launch since seven astronauts were killed when the shuttle Columbia disintegrated on Feb. 1, 2003, as it returned to earth.
NASA planners opted to move the shuttle despite a small crack in insulating foam on the external fuel tank, saying the crack posed no risk to the shuttle. Foam that came loose from Columbia’s tank during launch damaged that shuttle, leading to its break-up as it re-entered the Earth’s atmosphere.
The Discovery crew, finishing up pre-flight training at Houston’s Johnson Space Center, was cautiously upbeat about the approaching mission, though the astronauts said the last disaster forever changed such flights.
It’s also an emotional milestone for ground personnel such as flight director LeRoy Cain, who led mission control during Columbia’s ill-fated re-entry and will be doing the same job for the return flight. Cain said the earlier tragedy will be on his mind - but only to a point.
Is it going to cross my mind? I think I wouldn't be human if it didn't,'' Cain said. At the same time, he said, I don’t look at this as closure. I see it as a new beginning.’’
Before the launch, the shuttle still has to clear final evaluation by an independent oversight board. NASA’s sensitivity about foam damage was evident Wednesday when the agency delayed roll-out of Discovery for about two hours while they checked out the newly discovered small crack in the external tank foam.
NASA officials said the crack was about one-eighth of an inch wide and two inches long. Because of its small size and placement on the side of the tank facing away from the shuttle, mission planners decided it was unlikely to pose a risk to the spacecraft.
Astronauts on Discovery will bring carbon patches that could repair damage from falling foam or other debris. They’ll also have two different kinds of caulking material they could use to seal small holes or minor damage in case the thermal tiles were damaged during launch.
On Wednesday Cain guided the shuttle crew through three computer simulations of re-entry and landing, drilling the same crucial parts of the mission that caused Columbia’s destruction.
In the mock-up shuttle cockpit were pilot Jim Kelly and the mission commander, Eileen Collins, who in 1999 became the first woman to command a shuttle flight.
Collins and Kelly responded to a constant stream of mock malfunctions, including failures of computers controlling the shuttle’s wing flaps, a global positioning unit and vents that keep the payload bay from collapsing as the shuttle leaves the vacuum of space.
They will throw anything and everything at us,'' said Ronnie Montgomery, a data processing flight controller. One glitch Thursday was unintentional. A software error made the computer think the shuttle's external tank, which is ejected during the ascent to space, was still attached during re-entry. In that simulation the computer also gave readings suggesting the shuttle had landed about 1,000 feet underground - a problem that Collins laughed off. This is obviously not something you would see on a flight,’’
Collins said.
One of the main objectives of the mission is to replace parts on the International Space Station, including a gyroscope that keeps the outpost stable.
The astronauts also will be testing methods of repairing damage to the shuttle’s heat-resistant tiles and carbon panels on the leading edge of the wings. Investigators concluded that a hole on the leading edge of Columbia’s left wing let in hot plasma during re-entry, melting the wing and breaking the vehicle apart.
Stephen Robinson, one of the astronauts, said engineers still are testing a patching goo to see how it would work in the vacuum of space.
We view this as an experiment,'' Robinson said. We’ll learn more about it between now and the flight.’’
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Crew members said they have confidence in the safety changes NASA has carried out in the last two years, many of them geared toward avoiding - or at least detecting - the sort of damage that doomed Columbia.
NASA has installed new cameras to track the shuttle during flight, a laser scanner to look for damage during flight, and has overhauled the way workers install foam on the external tank.
It's inconceivable to me that we would miss damage to the vehicle, after all the work we're going to do,'' Discovery crew member Andy Thomas said. I think the issue for our flight and for subsequent flights is that there hasn’t been a vehicle processed down at (Cape Canaveral) in two and a half years. Prior to that, they had a rhythm. …
You just wonder is there some detail that someone has forgotten about, that someone has overlooked, that could have consequences,'' Thomas said. That, I think, is the more serious and more likely scenario.’’