NASA will start the launch countdown for Space Shuttle Atlantis' STS-115 mission at 8 a.m. EDT Sunday, Sept. 3, at the T-43 hour point.

During this mission, Atlantis' crew will resume construction of the International Space Station, which is the goal of the remaining space shuttle flights until the spacecraft are retired in 2010.

The first countdown for Atlantis' launch was stopped because of Tropical Storm Ernesto. The countdown includes 33 hours, 24 minutes of built-in hold time leading to a preferred launch time at approximately 12:29 p.m. EDT Wednesday, Sept. 6. The launch window for Wednesday extends an additional five minutes.

A detailed list of launch countdown milestones and times is available at:

http://www.nasa.gov/home/hqnews/2006/sep/HQ_06141_atlantis_countdown.html

This mission is the 116th space shuttle flight, the 27th flight for Atlantis and the 19th U.S. flight to the International Space Station. STS-115 is scheduled to last 11 days with a landing at NASA's Kennedy Space Center, Fla., about 8:03 a.m. EDT Sunday, Sept. 17.

Atlantis' last mission was STS-112 in October 2002. In preparation for STS-115, Atlantis was moved into Kennedy's Vehicle Assembly Building on July 24. Atlantis then was attached to its modified external tank and solid rocket boosters. Space Shuttle Atlantis was rolled out to Launch Pad 39B on Aug. 2. The initial launch date of Aug. 27 was scrubbed to evaluate the shuttle and its systems after a lightning strike at the launch pad. A partial rollback to the Vehicle Assembly Building took place Aug. 29 due to concerns about Tropical Depression Ernesto.

The STS-115 crew is Commander Brent Jett, Pilot Chris Ferguson, and mission specialists Joe Tanner, Dan Burbank, Heide Stefanyshyn-Piper and Canadian astronaut Steve MacLean.

During STS-115, Atlantis' astronauts will deliver and install the 17.5-ton, bus-sized P3/P4 integrated truss segment on the station. The girder-like truss includes a set of giant solar arrays, batteries and associated electronics. The P3/P4 truss segment will provide one-fourth of the total power-generation capability for the completed station.

For information about the STS-115 crew and mission to the pace station, visit:

http://www.nasa.gov/shuttle