Also at the pad is the payload canister containing the Harmony module that the STS-120 crew will deliver to the International Space Station. Harmony will be installed in Discovery's payload bay as launch preparations continue at the pad. Discovery and its seven astronaut crew are targeted to launch October 23 on the STS-120 mission to the International Space Station.

NASA needs to fly at least 11 more mission to the station to finish assembly before the shuttle fleet is retired in 2010. The agency also plans two station resupply missions and a final servicing call to the Hubble Space Telescope

STS-120 will be the twenty-third mission to the International Space Station and will deliver the U.S. Node 2 Harmony module expanding the space station's capability for future international laboratories.

Air Force Col. Pamela A. Melroy will command the STS-120 mission to take the Node 2 connecting module to the station. Melroy is the second woman to command a shuttle.

“STS-120 is such a cool mission,” says Commander Pam Melroy. “Node 2 is the expansion of the space station’s capability to bring international laboratories up. It’s the expansion of our capability to carry additional people. "It has additional life support equipment that will allow us to expand out beyond a three-person crew. It’s this big boost in the capability which is really exciting,” she said.

Built in Italy for the United States, Harmony is a high-tech hallway and Tinkertoy-like hub. It is a 23- by 14-foot passageway that will connect the U.S. segment of the station to the European and Japanese modules, to be installed later this year and early next year, respectively.

Harmony will be the first new U.S. pressurized component to be added to the station since the Quest Airlock was attached to one of Unity's six berthing ports in 2001.

Expedition 15/16 Flight Engineer Clayton Anderson will return to Earth from the space station aboard shuttle mission STS-120. That flight will carry his replacement, Daniel Tani, to the station. Tani will return on shuttle mission STS-122.

NASA officials plan a full schedule of five spacewalks for the next mission of US space shuttle Discovery.

During the fifth spacewalk the astronauts will test a tile patch repair equipment that could be used to fix heat-shield damage that can happen to shuttles during launch.

The so-called T-RAD was due to only be tested next year, but the trial was moved up in light of tile damage discovered during last month's Endeavour shuttle mission to the ISS.

On August 8, one minute after Endeavour’s launch, the debris, which likely had some SLA or ice attached, ricocheted off a metal strut to carve a gouge on space shuttle’s heat shield.

After Endeavour’s astronauts conducted a video inspection it was revealed that the gouge, located near the ship's right wheel well, was 30.5 x 25.5 millimeters (1.2 x 1.0 inches) large (smaller than initially reported) and 28.5 millimeters (1.12 inches) deep.

Though, NASA mission managers in Houston decided not to repair the space shuttle Endeavour’s heat shield. NASA said the damage was not enough to risk a catastrophic failure of the shuttle's heat shield, like the one that destroyed the shuttle Columbia on re-entry in February 2002, but the process of underside repairs during a spacewalk would have entailed risks for the astronauts.

On August 21, after twelve days spend in space, the space shuttle Endeavour landed safely at the Kennedy Space Centre in Florida, a day earlier than planned because of the hurricane Dean.