Discovery Shuttle undocks from station & heads home

Seven astronauts aboard the U.S. shuttle Discovery undocked from the International Space Station on Tuesday and set their sights on a Thursday landing in Florida. Shuttle pilot Kevin Ford backed the craft away from the station as it orbited 223 miles above western China, near the Mongolian border.

Later, Ford backflipped the shuttle around the station so astronauts aboard the outpost could take pictures of Discovery's heat shield. Discovery's crew will spend the rest of the day on inspections that are part of post-Columbia safety procedures to assure the shuttle was not damaged by debris during its climb to orbit.

In 2003, Columbia was hit by a suitcase-size chunk of foam that fell off its fuel tank during liftoff. The shuttle broke apart, killing the seven astronauts aboard, as it flew through the atmosphere for landing. So far, NASA has found no damage that would keep Discovery from its scheduled landing at the Kennedy Space Center in Florida on September 10 at 7:05 p.m. EDT (2305 GMT).

During its nearly 9-day stay, Discovery delivered more than 7 tons of food, supplies, equipment and spare parts to the $100 billion orbital outpost, a project of 16 nations that is nearing completion after more than a decade of construction.

Deliveries included science experiments, crew sleeping quarters, and a $5 million treadmill named after Comedy Central television host Stephen Colbert, who won naming rights to the station's final module after fans swarmed a NASA publicity campaign.

During three spacewalks, astronauts laid power cables that will be used to connect the outpost's last connecting node - named Tranquility -- to the station when it arrives in February. They also replaced a tank full of ammonia used to cool the station, installed an external cargo platform, and repaired a gyroscope used to steer the station.

NASA hopes to complete the station by the end of next year after six more shuttle flights. Construction began in December 1998. The station now weighs about 327 tons and is 84 percent complete