The shuttle landed right on time on NASA's 3-mile-long runway, illuminated by powerful xenon floodlights. "Field in sight on a beautiful night," radioed Commander Scott Altman, moments before the 4:32 a.m. touchdown.
Infrared cameras relayed pictures of the approaching spaceship, a ghostly, grainy image against the dark sky.
"It's great to be back here at Kennedy Space Center after this incredible experience at Hubble," Altman said.
He and his crew spent the past week working on Hubble, installing more powerful solar wings, a better central power controller and an advanced camera capable of peering across the universe almost to the beginning of time. By the time they released the observatory on Saturday, it had received $172 million worth of new gear.
"Welcome back and we'd like to congratulate you all on a very successful mission servicing the Hubble Space Telescope," Mission Control told the astronauts after the shuttle rolled to a stop.
Columbia logged nearly 4 million miles during its 11-day journey. Hubble, meanwhile, was pushing 1.8 billion miles after 12 years in orbit - roughly the distance from Earth to Uranus.
Earlier in the morning, the astronauts reported that a latch holding down one of Hubble's old solar wings had popped out a little in the shuttle payload bay. But Mission Control concluded, after analyzing pictures beamed down from orbit, that the wing was secure and would pose no safety hazard during touchdown.
The flight got off to a shaky start March 1 because of a clogged shuttle cooling line that threatened to bring the crew home early. But the astronauts went on to perform a record-tying five spacewalks over five days.
Besides giving Hubble the most advanced optical camera ever launched to study the cosmos, the astronauts added an experimental refrigeration system that NASA hopes will revive a disabled infrared camera. Scientists won't know if the repair worked for at least another month.
Even with the new camera alone, astronomers hope to look as far back as the first billion years of the universe.
NASA considered this its most challenging service call. Not only were the spacewalks difficult and jammed with work, the telescope had to be completely shut down for the power controller replacement, something that had never been intended. To scientists' relief, all of Hubble's systems came back on when power surged through the new controller.
Astronaut-astrophysicist John Grunsfeld said Hubble easily should make it to 2010, at which time NASA intends to decommission the observatory and bring it back for museum display. One more servicing mission is planned, in 2004.
As for Columbia, NASA plans to crack open the cooling system of its oldest space shuttle to find the debris that got stuck inside, probably from welding during an extensive overhaul.
Next up: a space station assembly flight in just three weeks by shuttle Atlantis. NASA needs to fix a problem with the international space station's construction crane, however, before Atlantis can be launched.
By Marcia Dunn