The ISS experienced problems when the steering system on the Russian segment was disabled last Tuesday by computer failure, which experts believe was caused by changes in the ISS configuration after new solar arrays were connected.
During the computer crash, the ISS crew used Atlantis' thrusters to help maintain the station's orientation. The computer glitch was fixed during the weekend, but NASA and Russian mission control officials considered the possibility of keeping the shuttle in orbit for one more day to ensure the station could maneuver in space independently.
A NASA spokesperson said that test results on Monday confirmed that computer systems on the ISS were working sufficiently to allow the Atlantis to depart on schedule, at 6.40 p.m. Moscow time (2.40 p.m. GMT) Tuesday.
The original 11-day mission has already been extended by two days after an inspection revealed slight damage to its thermal blanket.
In 2003 similar heat shield damage led to the disintegration of a Columbia shuttle, which resulted in the death of seven astronauts on re-entry into Earth's atmosphere.
The damage to Atlantis' thermal blanket was repaired during one of four spacewalks conducted by U.S. astronauts during their stay at the orbital station, which is expected to be completed by 2010.
Atlantis is scheduled to land at Cape Canaveral, Florida, on Thursday, at 9.52 p.m. Moscow time (5.52 p.m. GMT).
The shuttle is bringing back U.S. astronaut Sunita Williams, who spent more than six months in space, setting a record for the longest uninterrupted spaceflight by a woman.
