With five days of pilfering power from the International Space Station under their belt, mission managers today decided to extend space shuttle Endeavour's flight from 11 to 14 days.

The crew is now scheduled for undocking on Aug. 20 for an Aug. 22 landing. The three extra days are made possible by the new Station-to-Shuttle Power Transfer System, which allows the shuttle to draw power from the station while docked. The crew members will use the extra time to add a fourth spacewalk, during which Mission Specialist Dave Williams and space station Flight Engineer Clay Anderson will install equipment used to stow the Orbiter Boom Sensor System at the station between shuttle flights.

Mission managers decided Sunday to extend the STS-118 mission by three days. The decision came after the successful operation of the new Station-to-Shuttle Power Transfer System (SSPTS).

Endeavour is now scheduled to undock from the International Space Station on Aug. 20 and land Aug. 22. In addition to the extra time at the orbital outpost, managers added a fourth spacewalk that is scheduled to take place Aug. 17.

The SSPTS reroutes power from the space station to the shuttle during docked operations, allowing the orbiter to conserve materials needed to generate power and spend more time in space.

Already the largest human-made object orbiting the Earth, the International Space Station continued its on-orbit growth spurt with the addition of the Starboard 5 (S5) truss segment. The S5 was attached at about 1:35 p.m. EDT during STS-118's first spacewalk.

The S5 will serve as a spacer segment between the Starboard 4 and 6 (S6) segments. The S6 and its solar arrays will be attached during a future shuttle mission. The S5 is the newest piece of the station's backbone, called the Integrated Truss Structure, which will eventually span the length of a football field and contain four sets of solar arrays.

HOUSTON -- Astronauts aboard NASA's space shuttle Endeavour will take a close look at a gouge on the underbelly of their orbiter Sunday while mission managers decide whether to add a few extra days to their flight to the International Space Station (ISS).

"The primary thing that we're going to look for is how deep it is," John Shannon, chairman of Endeavour's STS-118 mission management team, said of the damage during a Saturday briefing here at NASA's Johnson Space Center.

A piece of foam insulation about the size of a grapefruit fell from a bracket on Endeavour's external tank and bounced off a metal strut to damage the belly-mounted tiles during the orbiter's Aug. 8 launch. Radar images caught a spray of debris and possible ice reminiscent of that seen during the debris hit that led to NASA's 2003 Columbia accident, but Shannon said the event was much less severe than that which afflicted Columbia.