The U.S. space agency NASA has postponed the scheduled launch of a private cargo supply ship because the crew at the International Space Station needs to repair a faulty pump.
Astronauts Rick Mastracchio and Mike Hopkins are scheduled to work outside the space station December 21, 23 and 25. NASA said Wednesday that each of the spacewalks will last six and a half hours.
The malfunctioning part in one of the two cooling units is located outside the station, so the mission will involve a series of spacewalks.
Meanwhile, the station will be using the backup system for cooling both internal and external equipment.
Orbital Sciences' Antares rocket, with cargo spacecraft Cygnus sitting on top of it, is now rescheduled for launch in mid-January.