Posted: Thu, Jul 19, 2001, 11:24 AM ET (1524 GMT)

Shuttle and station astronauts replaced a leaky air circulation valve in the new Quest airlock module of the International Space Station Wednesday night. The leak was first noticed on Sunday, after the airlock was attached to the station, and could not be immediately isolated and fixed. Astronauts replaced the faulty valve with a spare one from the Destiny module that will not be needed until a new node module is attached to it in 2003. However, Thursday morning station officials said they found several minor air leaks that the shuttle and station crews are currently investigating. The shuttle also used its thrusters to reboost the station's orbit overnight; combined with previous thruster firings, Atlantis has increased the altitude of the station by 16 kilometers. The STS-104 crew is also preparing for one final spacewalk on Friday night by astronauts Mike Gernhardt and Jim Reilly to complete the installation of air tanks on the exterior of Quest. That spacewalk will be the first to use the new airlock module.