Mission in vain

When the wheels of the space shuttle Discovery at last rolled to a safe stop at the end of a dusty runway before dawn in the California desert, the rest of America's human-spaceflight programme began to accelerate into an unknown future.

After more than two years of research and repair, the primary problem that downed Columbia remains. Foam continues to fall from the fuel tank during liftoff and the shuttle fleet will not fly again until the situation is corrected.

Before Discovery was launched, shuttle managers had all but promised that no foam chunks the size of the one that smashed a hole in Columbia's left wing would break free of the tank this time. Yet one of the new cameras mounted beneath Columbia clearly showed a large piece falling from an area near the fuel tank's liquid-hydrogen pipe an area called the protuberance air load (PAL) ramp.

Significantly, this is an area of the fuel tank that Nasa did not redesign after Columbia. Engineers felt other areas needed more urgent attention, pushing the PAL ramp off the priority list.

Administrator Michael Griffin has since acknowledged that this was a mistake. But shuttle engineers note that the areas of the tank that were redesigned performed well, with little foam shedding. And they are optimistic that similar changes will resolve the problem with the PAL ramp and allow a quick return to space.

Foam loss

In a press conference on Tuesday morning, Nasa officials were hesitant to guess when the shuttle would return to flight, but some engineers have insisted that the foam loss during the launch was not as devastating to the programme as has been suggested.

Aside from tending to the International Space Station, getting the "real data" on how the shuttle redesigns worked was the primary function of this mission.

Now mission managers know they can get highly detailed images of the shuttle. They know that astronauts can tinker under the shuttle without damaging the heat-resistant tiles.

And they know how the space station can lend its long arm to help. To some, the tinkering could become a common occurrence as new images show mission managers more of the shuttle's nicks and dings than they have ever seen before.

Critics see this as further proof of the shuttle's flaws both the machine and the mission. While space exploration is worth a degree of risk, they say, the shuttle and space station are more about politics and international prestige than science.

If anything, though, Discovery has bound the fates of the shuttle and the space station even more closely together. The shuttle programme exists only to complete construction of the unfinished space station.

Yet this mission suggests that one of the space station's most valuable functions might be as an orbital garage something that was in the first plans for the station but was eventually scrapped as costs spiralled.

"It is being pushed in the direction of its original vision," says Howard McCurdy, a Nasa historian. "It is an inadvertent turning point arising as a result of the Columbia accident."

- The Christian Science Monitor