The Atlantis crew's most important job is to nudge the space station back to the correct altitude.
One of the most spectacular liftoffs in the history of NASA's space shuttle program provided an optimistic sendoff for a mission already known for headaches.
As the shuttle Atlantis climbed into the still-dark sky at 6:11 a.m. Friday, the spacecraft and its billowing plume of smoke were suddenly bathed in light from the sun rising over the eastern horizon.
It was an unexpected moment of beauty, and a chorus of approving murmurs rose from observers at the Kennedy Space Center.
So much for cosmetics. NASA and the seven-member crew of Atlantis went quickly to the task at hand: jump-starting the assembly of the frustrating, costly and behind-schedule International Space Station.
Atlantis will deliver more than a ton of supplies and parts to the station, including four big electricity-generating batteries to replace those already failing. A new cargo boom will be attached and a smaller one that had come loose will be tightened.
But perhaps the most important thing the crew will do is nudge the station back to the correct altitude. Increased solar wind has increased the "drag" the station experiences as it orbits Earth, so much so that it has been falling at the rate of almost 2 miles per week.
After docking and unloading supplies, Atlantis will fire its rocket motors to lift the station about 26 miles, back into the proper, slightly elliptical orbit about 229 miles above Earth.
But the need for this orbital boost highlights NASA's long-simmering problems with the Russian Space Agency.
The International Space Station should be able to make this kind of altitude adjustment on its own. And when it is complete, a Russian-built "service module," called Zvezda, will give the station this capability. Zvezda also will provide crew quarters.
Zvezda, however, is more than two years late getting into space. It is now scheduled for launch from the Russian Baikonur launch site in mid-July. Friday's mission was supposed to follow Zvezda into space, but had to be moved up to adjust the station's deteriorating orbit.
NASA spokesmen say they are confident the Russians will launch in July. Problems with Proton booster rockets have been resolved, said James Hartsfield of NASA headquarters, "and we think they are ready to go."
Thus far, the Russians have been problem partners. A struggling economy has left their space program strapped for cash and behind schedule. They agreed to launch the service module in mid-July only after NASA administrator Dan Goldin, under increasing pressure from Congress, said he was preparing to launch an American-built replacement.
Earlier this year Goldin said he was "frustrated and disappointed" by the delays, and said the United States and other nations involved in the construction could no longer afford to wait.
"We're at the moment of truth," he said. "It is up to the Russians to demonstrate . . . their commitment."
And there have been problems with what the Russians have contributed thus far.
During the current mission, the Atlantis crew will have to wear earplugs while working inside the Russian half of the station because of the racket from whirring equipment. _ Times researcher Caryn Baird contributed to this report. Information from the Associated Press was used.