Astronauts from the U.S. space shuttle Discovery have completed their second spacewalk outside of the International Space Station orbiting the Earth.
Sunday's seven-and-a-half hour spacewalk was partially successful, as Clayton Anderson and Rick Mastracchio installed a new ammonia tank used to cool the space station.
However, a troublesome bolt led to the astronauts falling behind schedule, leaving them unable to complete other assigned tasks, such as installing fluid connections to the ammonia tank and retrieving two debris shields.
This was the second of three spacewalks to be completed during their two weeks in space.
The Discovery crew's other tasks while at the space station are to retrieve a Japanese experiment from the station's exterior and replace a gyroscope.
The U.S. space agency NASA earlier extended Discovery's mission in space by a day to allow time to review a routine inspection of the shuttle's heat shields.
Discovery is now scheduled to land April 19 at Kennedy Space Center in the southeastern U.S. state of Florida.
Some information for this report was provided by AP, AFP and Reuters.