Two crew members of the International Space Station have completed a nearly seven-hour spacewalk aimed at determining the cause of electrical problems at the orbiting outpost.

Station commander Peggy Whitson and flight engineer Daniel Tani ventured into open space early Tuesday to search for the cause of a partial loss of electrical power to a mechanism that controls a solar panel on the station. This was the 100th spacewalk devoted to space station assembly and maintenance.

The U.S. space agency, NASA, also says Whitson set a new record for cumulative spacewalk time for a woman, with a total of 32 hours and 36 minutes in five walks. She surpasses the mark set by Sunita Williams, who had a total of 29 hours and 17 minutes during four spacewalks.

Meanwhile, NASA officials are trying to determine what caused fuel sensors to fail in the space shuttle Atlantis, leading to the postponement of the shuttle's launch last week. Another attempt is scheduled for January.

Some information for this report was provided by AFP, AP and Reuters.