Atlantis made the final docking of the 30-year space shuttle program on Sunday, hooking up with the International Space Station for a final resupply rendezvous.

Aboard the station, NASA astronaut Ron Garan rang a bell to mark the shuttle's arrival in traditional naval fashion.

"Atlantis arriving," he declared. "Welcome to the International Space Station for the last time."

"And it's great to be here," Atlantis commander Chris Ferguson replied.

During this 135th and final space shuttle mission, Atlantis is delivering more than four tons of food, clothes, spare parts, experiments and other space station supplies to keep the complex going in the post-shuttle era. NASA figures that this shipment will help keep the space station provisioned through the end of next year.
Computer glitch and potential space junk
The mission's lead flight director, Kwatsi Alibaruho, said Atlantis' crew encountered a "slight problem" well before the docking sequence when one of the shuttle's computers failed during the morning power-up. He explained that the computers' on-off switches "can be a little bit temperamental from time to time." If they're not flipped on decisively, that could create a glitch — which is apparently what happened on Sunday.

The shuttle uses three computers simultaneously to provide redundancy, and the glitchy computer was "voted out" and taken offline. Alibaruho expected that a Monday-morning reset would put the system right again. He also noted that the shuttle has two spare computers, just in case there's a hard failure.

Later in the day, mission management team leader LeRoy Cain said a piece of space junk might come close to the docked shuttle and station on Tuesday, the same day that the sole spacewalk of Atlantis' mission is scheduled to take place.

Cain didn't yet have details about the trajectory or precise nature of the debris, but he said that if the orbital path came too close, the shuttle could fire its thrusters to move the station out of the way.

'Powerful moment'
Alibaruho said Sunday was a "big game day" because of the last shuttle docking, and the gravity of the occasion sank in among members of the flight team at Johnson Space Center in Texas.

"It was a powerful moment for me. ... I was not feeling sadness, but that understandable and common and sober anticipation of what's coming next," Alibaruho told journalists.

This was the 46th docking by a space shuttle to a space station. Nine of those were to Russia's Mir station back in the mid-1990s. The U.S. and Russia built on that sometimes-precarious experience to create, along with a dozen other nations, the world's largest spacecraft ever: the permanently inhabited, finally completed, 12-year-old International Space Station.

Ferguson was at the controls as Atlantis closed in, leading the smallest astronaut crew since 1983.

Only four are flying aboard Atlantis, as NASA kept the crew to a minimum in case of an emergency. In the unlikely event that Atlantis was seriously damaged, the shuttle astronauts would need to move into the space station for months and rely on Russian Soyuz capsules to get back home. Since the 2003 Columbia tragedy, a shuttle had always been kept on standby for a possible rescue, but that's no longer feasible with Discovery and Endeavour officially retired now.

A video view captured from the shuttle Atlantis shows the International Space Station during the approach for Sunday's docking.

NASA said Atlantis seemed free of significant damage. But as a safeguard, the shuttle performed a final backflip for the space station cameras, an hour before the 230-mile-high (370-kilometer-high) linkup. The station astronauts captured high-resolution photos of the shuttle's protective tiles during the maneuver.

The orbital ballet move was executed without a hitch. "Poetry in motion," NASA mission commentator Rob Navias said. Over the next couple of days, experts on the ground will scrutinize the digital images for any signs of damage that might have come from fuel tank foam, ice or other launch debris.

Two hours after the docking, Atlantis' crew of four floated into the space station for a round of hugs and picture-taking with the space station's six-member crew. Because of the shuttle fleet's retirement, it could well be years before so many people are in space together again.
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