Orbiter Docks With ISS; Power Transfer System Activated

A detailed inspection Friday of the heat shield of the shuttle Endeavour detected a potentially worrisome gouge in the tiles near the orbiter's starboard main landing gear door.

"What does this mean? I don't know at this point," said mission management team chairman John Shannon.

The damage was detected shortly after Endeavour docked with the International Space Station at 1404 EDT Friday. Astronauts will use the orbiter's robotic arm to take a closer look at the suspect area Sunday, using laser sensors to measure the exact size and depth of the scar.

NASA says the damage may have been caused by a chunk of ice falling from the shuttle's external tank during launch. If it was ice -- which is much more dense than the foam insulation that struck the leading edge of a wing on Columbia in 2003, that led to the loss of the orbiter -- engineers believe it may have pierced the tile and broken up, causing the three-inch-square gouge.

The agency says if necessary, astronauts on Endeavour will conduct a spacewalk to patch the damage -- a process devised in the aftermath of the Columbia tragedy.

Images taken during Endeavour's launch Wednesday night show a white object falling away from the shuttle 58 seconds after liftoff, and several streaks were seen near the gouge.

In all, nine pieces of debris, primarily foam, fell from the fuel tank; three are believed to have struck the orbiter. Shannon said further examination could reveal more damage, although such hits are relatively common during launch.

Meanwhile, the STS-118 and Expedition 15 crews are conducting joint operations aboard Space Shuttle Endeavour and the International Space Station.

For the first time ever, the crews also activated the Station-to-Shuttle Power Transfer System (SSPTS) Friday. The SSPTS is designed to reroute power from the station to a visiting shuttle.

If the transfer system works as expected, mission managers could elect to extend STS-118’s mission from 11 to 14 days and increase the number of spacewalks from three to four. A decision on a possible extension could occur Sunday.

The two crews are preparing for STS-118's first spacewalk, which is set to begin at 1231 EDT Saturday. The spacewalkers will assist in the installation and activation of the Starboard 5 (S5) truss. Friday’s preparations included transfer of spacewalk equipment and the review of procedures. Also, the two crews used the shuttle robot arm to lift the S5 out of the payload bay and hand it off to the station robotic arm.

The two spacewalkers, Mission Specialists Rick Mastracchio and Dave Williams, will enter the station’s Quest airlock where they will spend the night. This procedure is performed to help prevent decompression sickness.

FMI: www.nasa.gov