NASA is targeting a possible launch of Space Shuttle Atlantis on Friday, Sept. 8 because of a problem associated with one of the spacecraft's electricity-producing fuel cells. Shuttle program managers at NASA's Kennedy Space Center decided Wednesday afternoon additional time was needed to evaluate fuel cell flight history and potential causes of the malfunction.

Mission managers will hold another meeting Thursday at 1 p.m. EDT to assess the issue. There will be a news conference on NASA Television at the conclusion of that meeting. If the team decides to "go" for launch Friday, lift-off would be at 11:41 a.m. EDT.

Tuesday night as ground teams were preparing for Atlantis' scheduled launch Wednesday, a voltage spike in the motor of Atlantis' fuel cell #1 coolant pump was observed during the activation of the shuttle's three fuel cells. The coolant pump flows Freon through the fuel cell to prevent it from overheating during flights.

During Atlantis' mission, STS-115, astronauts will deliver and install a girder-like structure, known as the P3/P4 truss, aboard the station. The 35,000-pound piece includes a set of giant solar arrays, batteries and associated electronics. The arrays eventually will double the station's power capability.

Atlantis' crew, Commander Brent Jett, Pilot Chris Ferguson and mission specialists Dan Burbank, Heide Stefanyshyn-Piper, Joe Tanner and Steve MacLean, a Canadian Space Agency astronaut, will remain at Kennedy Space Center while the fuel cell evaluation continues.

For the latest information about the STS-115 mission and its crew and more information about space shuttle fuel cells, visit:

http://www.nasa.gov/shuttle