A spacewalk, and a mentality shift
For NASA, first-ever spacewalk beneath a shuttle represents a more aggressive approach to problems.
As astronaut Steve Robinson dangled from the spindly limb of the space station's robot arm 220 miles above the pale blue crescent of Earth, many Americans watched with utter fixation as the nation's spaceflight program took one giant step toward returning to its legendary past.
It was but a single hour, and the removal of two pieces of gap filler protruding from beneath the shuttle Discovery turned out to be as routine as a spacewalk could be. But the event had a significance beyond the safety of the shuttle.
To some space experts, the mission symbolized the spirit of derring-do forged by NASA a generation ago. The shuttle Columbia was lost in large part because NASA's "can do" attitude had waned amid the frustrations of tight budgets and a temperamental vehicle.
The same problems still exist. But Wednesday's spacewalk suggests that NASA will not let itself be defined by them but hopes to return in part to the ethic of old, even if it means delays on the launch pad or sending astronauts under the shuttle with pliers and a lug wrench.
Throughout most of the shuttle era, "the approach was to ask if anybody could sit up and prove there was a danger," says Howard McCurdy, a NASA historian.
"Now the question is: Can anybody prove that this is not a danger? It is a shift. NASA is going back to the approach it had during the 1960s."
It was this mentality that brought Mr. Robinson almost to within kissing distance of the shuttle's sensitive tiles Wednesday.
While NASA had made provision to send astronauts under the shuttle in the case of tile damage, no one had foreseen the problem that engineers spotted when Discovery arrived in space. Two of the thin fabric fillers wedged between shuttle tiles had come loose and were peeking above the smooth skin of Discovery's belly.
The first reaction was to do nothing. The fillers might cause extra heating on reentry by disrupting the airflow across the shuttle's underside, but there was no proof that this would have dire consequences. Then, over the weekend, the thinking changed.
"They had a hard time showing that there was no risk," says James Oberg, a former shuttle engineer. "And if you can't prove it's safe, you have to do something about it."
As they became more concerned about the fillers, however, they became less concerned about the potential remedy. True, no astronaut had ever gone beneath the shuttle on a spacewalk, but when engineers got down to calculating space-station arm angles and backup plans, it didn't seem as daunting as some had suspected.
"When people first looked at it, it looked risky," says Dr. Oberg. "All the managers went through this stage, but the more they went though the hazards, the more they were satisfied."
In the end, Robinson needed none of the tools in his spacewalker's tool kit. He simply pinched the two pieces of filler between his thumb and forefinger and eased them out of the slot between tiles. Though the fillers do serve a function, they are more important during liftoff than landing, and engineers believed that the protrusion made them more of a risk than a benefit.
For the astronauts, it was almost everyday work - not nearly as difficult as the spacewalk in 1992 when an astronaut had to grab a floating satellite with his hands. Whether it becomes a regular part of space-station detail, however, is anyone's guess.
Certainly, engineers are seeing more pictures of the shuttle than they ever have before, so they may be seeing things for the first time that in fact occurred on many missions. But NASA scientists don't think so. "[They're] still thinking this is a coincidence - that this is the biggest the gap fillers have ever gotten," says Oberg.
The next shuttle mission will begin to answer the question, and engineers will be looking for clues. Indeed, the spacewalk suggests that NASA has fundamentally changed the way it looks at the shuttle, seeing it as a truly experimental vehicle.
For years, NASA managers were loath to make this concession. It amounted to an admission of defeat. The shuttle was intended to be an operational vehicle - something that made going into space almost routine.
The loss of Columbia, however, forced NASA to accept that its orbiters require the vigilant eye of engineers who prepare for the worst. The lesson from Wednesday is that this preparation pays off.
The mission has swung from the euphoria of a seemingly clean liftoff to the despair of the grounding of future shuttle flights until engineers can solve the problem of foam breaking off the fuel tank - the same problem that downed Columbia. But the foam problem seems to be only in an area that was not redesigned after Columbia, raising hopes for a quick fix. And to some degree, this is what is expected of an experimental flight.
This is a "mission to find out what works and what doesn't," says John Logsdon of the Columbia Accident Investigation Board. "And it has been a very successful mission."
To him, the spacewalk is further proof that NASA now has the mind-set to put things right. "The NASA that was flying Columbia was rejecting information," he adds. "This NASA is accepting information ... and acting on it in a very judicious and prudent way."