Updated: Tue, Jul 17, 2001, 3:13 PM ET (1913 GMT)
Originally Posted: Tue, Jul 17, 2001, 11:46 AM ET (1546 GMT)

Two shuttle astronauts are gearing up for a second spacewalk outside the International Space Station tonight despite problems that led shuttle managers Tuesday to extend the mission by one day. Astronauts Mike Gernhardt and Jim Reilly will leave the shuttle at about 10:30 pm EDT Tuesday (0230 GMT Wednesday) for their second spacewalk of the STS-104 mission, a 5.5-hour effort to attach nitrogen and oxygen tanks to the exterior of the new Quest airlock on ISS. Shuttle managers reportedly considered delaying the spacewalk as the shuttle crews fell behind their scheduled timeline Monday tracking down and trying to fix a leaking air valve in the module. The leak was not pinpointed, but a cap was installed that stopped the leak temporarily. That, combined with work to remove air bubbles in a water coolant line, put the crew about a half-day behind schedule. In response, NASA announced Tuesday that it has extended the mission by one day to give astronauts more time to complete their tasks. This will delay the third and final spacewalk of the mission from Thursday to Friday night and push back Atlantis's departure from the station to Saturday.