HOUSTON -- Atlantis was cleared yesterday to return to earth this week after the space shuttle's heat shield was judged capable of surviving the intense heat of reentry, and US astronaut Sunita Williams reached a milestone with the longest spaceflight by any woman.
Atlantis is set to land at Cape Canaveral, Fla., on Thursday, although NASA officials were still deciding whether to keep the shuttle at the international space station for an extra day because of a failure of computers that control the station's orientation and oxygen production.
"That's great news," Atlantis commander Rick Sturckow said of the landing plan.
The shuttle's 11-day space station construction mission had been extended to 13 days so a thermal protection blanket could be fixed during an unscheduled spacewalk. NASA has been particularly sensitive about the space shuttles' heat shields since the Columbia accident killed seven astronauts in 2003.
Williams, a former Massachusetts resident known as "Suni," has lived at the space station since December. She surpassed the record of 188 days set by astronaut Shannon Lucid at the Mir space station in 1996.
"It's just that I'm in the right place at the right time," Williams, 41, said when Mission Control in Houston congratulated her on the record. "Even when the station has little problems, it's just a beautiful, wonderful place to live."
Those "little problems" had been considerable in recent days with the computer system failure on the Russian side of the station. Cosmonauts Fyodor Yurchikhin and Oleg Kotov got four of six processors on two computers working again on Friday, and yesterday they got the remaining two on line.
Engineers in Moscow and Houston had not conclusively determined what caused the failure, although the leading theory was changes to the electrical system from the space station's growth.
The cosmonauts started turning on systems -- such as an oxygen machine, a water processor, and a carbon dioxide remover -- that had been turned off while the computers were down. Today, they plan to test the station's orientation system, which will be the final benchmark for deciding whether the computers work properly and whether the shuttle needs to stay an extra day.
"The bottom line is it appears that the command and control type computers are functioning just fine," said Mike Suffredini, NASA's space station program manager.
In preparation for Tuesday's scheduled undocking of the shuttle, astronauts and cosmonauts spent yesterday moving supplies and trash between the shuttle and station .
Friday's tasks had included spacewalks to repair the torn thermal blanket on Atlantis and to retract a 115-foot solar energy wing that will be moved to a different location on the space station.
Williams's former crew mate at the space station, astronaut Michael Lopez-Alegria, holds the US record for longest continuous stay in space with 215 days. The longest stay in space was 437 days by Russian Valeri Polyakov.
In February, Williams set another record for the most time spent spacewalking by a woman, kicking off a year of achievements by women in space.
In October, US astronaut Peggy Whitson will become the first woman to command the space station. Later that month, Air Force Colonel Pam Melroy will become the second woman to command a space shuttle mission; Eileen Collins was the first, in 1999.