'We're back, baby': astronaut after final spacewalk

The assessment of the current space shuttle mission to the International Space Station came from NASA astronaut Scott Kelly. His brother, Mark Kelly is now in orbit, serving as the pilot for Space Shuttle Discovery during the two-week mission.

Wrapping-up what the U.S. space agency considers the first trouble-free shuttle mission since the Columbia disaster, Discovery astronauts Piers Sellers and Mike Fossum conducted their third and final spacewalk Wednesday afternoon, which ended at 2:31 p.m. ET.

The astronauts tested sealant used to fix cracks on the tiles that make up the shuttle's heat-shield, which must withstand extreme temperatures during the return trip back through Earth's atmosphere.

The test was to prevent the shuttle from suffering the same fate of Columbia in 2003, when a piece of foam came off the shuttle's fuel tank and struck a wing panel. Columbia broke apart on its return to Earth, killing all seven astronauts aboard.

While on the final spacewalk of this mission, Sellers and Fossum also demonstrated an infrared camera, used to detect invisible damage on the shuttle.

According to the astronauts, the Discovery mission's two main priorities have now been met: to avoid bigger shuttle-related problems, and to get the International Space Station ready for more construction.

Earlier in the day, the astronauts took a few spare minutes to receive a call from U.S. President George W. Bush, congratulating them on the mission.

The shuttle is now cleared to come home. Its return date is scheduled for July 17.

Photography: NASA

Source: Discovery Channel Reports, July 12 edition