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Space shuttle Atlantis is cleared to land next week

Mission managers cleared Atlantis to land next week as the space shuttle's heat shield was safe enough.

"That's great news!" Atlantis commander Rick Sturckow radioed to Mission Control after receiving word that Atlantis is cleared to land at Cape Canaveral, Florida, on Thursday.

The clearance came a day after astronaut Danny Olivas, during a spacewalk, stapled down a loose thermal blanket that covered an engine pod near the shuttle's tail. The blanket peeled back during last week's launch.

NASA has been sensitive about the space shuttles' heat shields ever since the Columbia accident killed seven astronauts in 2003. Foam from the shuttle's external tank came loose during launch, striking Columbia's wing and allowing fiery gases to penetrate it during re-entry.

Also Saturday, Russian cosmonauts began turning back on some crucial systems that had been shut down more than four days ago when a computer system on the Russian side of the international space station crashed.

The first system turned on was a machine that scrubs carbon dioxide from the air inside the space station.

Just a day earlier, Fyodor Yurchikhin and Oleg Kotov were able to get four of six processors on two computers working again by using a cable to bypass a circuit board.

"In the last 24 hours, we've had a lot of successes," flight director Holly Ridings said Saturday morning.

NASA officials said the crew was never in danger of running out of oxygen, power or essentials.

The computers on the Russian side provide oxygen and maintain the space station's correct position in orbit, allowing it to point its solar arrays at the sun for power and shift orientation to avoid occasional large debris that comes flying through space.

The computer problem had raised the possibility the space station's three-person crew might have to abandon the outpost. NASA officials rejected such a scenario.

"We feel like the computers are stable and back to normal," said Mike Suffredini, NASA's manager of the space station program.

The cosmonauts used another jumper cable Saturday to get the last two failed processors on the computers working, Ridings said Saturday morning.

Suffredini, however, said Friday night that engineers do not expect the other two processors to come back online. They will be replaced.

Engineers were still trying to determine what caused the computers to fail, Suffredini said.

Early Saturday, U.S. astronaut Sunita Williams set the record for the longest single spaceflight of any woman, passing astronaut Shannon Lucid's record of 188 days in space.

"It's just that I'm in the right place at the right time," Williams said when Mission Control congratulated her. "It's just an honor to be up here. Even when the station has little problems, it's just a beautiful, wonderful place to live."

The seven astronauts visiting on space shuttle Atlantis and the three space station crew members planned to spend most of Saturday moving supplies and trash back and forth between the vehicles and preparing for the mission's fourth spacewalk on Sunday.

The 11-day space station construction mission had already been extended by two days so the rip in the shuttle's thermal material could be fixed.

The failed computers were the latest technical glitch for the half-built, $100 billion (EUR75.1 billion) outpost. A Russian oxygen machine and gyroscopes, which also control orientation, have previously failed.

The computer problem renewed criticism of the space station, which has been called an ill-conceived venture, as well as criticism of U.S. President George W. Bush's "Vision for Space Exploration," which calls for finishing the space station in three years, grounding the space shuttles in 2010 and building next-generation vehicles to go to the moon and Mars.

"We're learning a great deal from the space station, and one of things we may be learning is we shouldn't have built this particular one," said Howard McCurdy, a space public policy expert at American University.