HOUSTON -- All six of the computers that went down aboard the international space station are up and running again.

Engineers in Moscow and Houston have not yet fully figured out what caused the failure on the Russian side of the station.

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. Tomorrow, they plan to test the station's orientation system. That will be the final benchmark for deciding whether the computers work properly and whether the docked space shuttle needs to stay an extra day.

And this historical note: U.S. astronaut Sunita "Suni" Williams Saturday set a record for the longest single spaceflight by any woman. Williams surpassed the record of 188 days set by astronaut Shannon Lucid at the Mir space station in 1996.

Earlier Saturday, NASA mission managers concluded the heat shield on Atlantis is safe enough for the space shuttle to return to Earth.

They've cleared Atlantis to land at the Kennedy Space Center on Thursday. Astronauts stapled down the loose corner of the vehicle thermal blanket during a spacewalk Friday. They'll make another inspection of it before attempting to return.

Friday, astronaut John "Danny" Olivas used his hands, staples from a medical kit and pins to repair a thermal blanket on the back end of space shuttle Atlantis that came loose during liftoff a week ago.

Olivas completed his work as Jim Reilly changed a vent on the outside of the international space station.