NASA Starts Space Shuttle Endeavour Countdown Aug. 4

During the 11-day mission to the International Space Station, Endeavour's crew will add another truss segment to the expanding station, install a new gyroscope and add an external spare parts platform.

The flight will have at least three spacewalks. It also will debut a new system that enables docked shuttles to draw electrical power from the station to extend visits to the outpost. If this system functions as expected, three additional days will be added to the STS-118 mission.

This mission is the 119th space shuttle flight, the 20th flight for Endeavour and the 22nd U.S. flight to the International Space Station. The mission will be Endeavour's first flight in more than four years. The shuttle has undergone extensive modifications, including the addition of safety upgrades already added to shuttles Discovery and Atlantis.

Source: NASA