HOUSTON (AP) _ A revived set of crucial computers aboard the international space station still need to undergo one more test before they are given a clean bill of health.
That test _ set to be done Monday _ will determine if the two Russian computers are ready to control the station's orientation.
Test results will help determine if space shuttle Atlantis, which has been at the space station since June 10, needs to spend another day at the outpost.
During the computer meltdown last week, Atlantis' thrusters were used to help the station maintain its position. The space station's thrusters haven't been used since the computers failed.
``That's a big step in our checkout of the computers to make sure everything is working correctly,'' flight director Holly Ridings said Monday. ``It's one of those things we want to see before we undock.''
Atlantis is set to undock on Tuesday and land Thursday in Cape Canaveral, Fla.
The Russian computers, which also control oxygen production, crashed last week. All six of the computers' processors were back online Saturday. The two processors that took longer to revive are now on standby mode and can be used if needed.
Except for an oxygen generator, all the space station systems that were powered down when the computers failed are now running.
During Monday's test, the space shuttle's thrusters will take control of the joined craft so it can change positions to dump waste and water, and then the Russian thrusters will take over. During a second part of the test, U.S. computers will send commands to the Russian thrusters.
Also Monday, Atlantis' crew was to finish packing the shuttle for its return trip to Earth. The shuttle and space station crews were set to say their goodbyes before hatches between Atlantis and the outpost are closed in preparation for Tuesday's undocking. They were given some free time Monday morning to enjoy the view on their last full day in space.
On Sunday, shuttle astronauts completed the fourth and final spacewalk of their mission to continue the construction of the space station.
During a nearly 6 1/2-hour spacewalk, astronauts Patrick Forrester and Steven Swanson activated a rotating joint _ their top priority _ on the outpost's newest segment so a new pair of solar wings can track the sun and provide power to the station. The solar arrays were delivered to the space station by Atlantis.
The astronauts also set up a new camera stanchion outside the station's newest segment and a computer network cable between the U.S. and Russian sides of the outpost. They were not able to bolt down a problematic debris shield and instead secured it in place.
Early Monday, flight controllers successfully gave the rotating joint a small test by moving it 5 degrees. During a more thorough test later in the morning, the joint began rotating automatically, allowing the solar arrays to track and sun and provide power to the station.
``The checkout went really well last night,'' Mission Control told the astronauts Monday morning.
While the seven-member crew of Atlantis and the three-man crew of the space station spent Father's Day 220 miles above Earth, the holiday didn't slip the minds of the nine fathers at the outpost, who collectively have 24 children.
``Happy Father's Day to everybody downstairs,'' said U.S. astronaut Clay Anderson.