Astronauts from the space shuttle Discovery have completed the first of two planned spacewalks outside the International Space Station.
Crew members Steve Bowen and Alvin Drew ventured out of the hatch ahead of schedule Monday and ended their spacewalk after less than seven hours. They completed several maintenance jobs, including the installation of an extension to a power cable. They also prepared the space station for a new storage unit called the Permanent Multipurpose Module.
The two astronauts also collected a sample of the vacuum of space for a Japanese space agency experiment - Message in a Bottle. That sample will be brought back to Earth for public display.
Monday's venture outside the space station was Drew's first and Bowen's sixth career spacewalk. Bowen is the first astronaut to make back-to-back shuttle missions. He flew aboard the space shuttle Atlantis last May.
Bowen was added to the Discovery crew in late January as a replacement for astronaut Tim Kopra, who could not make the flight after he was injured in a bicycle accident.
Bowen and Drew are scheduled to make another spacewalk on Wednesday.
The 11-day mission is the last for the space shuttle Discovery.
The shuttle, first launched in 1984, has flown on 38 missions, more than any other shuttle in the NASA fleet. It carried the Hubble Space Telescope into orbit in 1990, and was the first shuttle to travel to Russia's Mir Space Station.
The United States is ending its space shuttle program 30 years after the first launch.
The shuttles Endeavour and Atlantis each have one mission left.
Some information for this report was provided by AFP and AP.