CAPE CANAVERAL, Fla. - NASA has put off a major repair job at the International Space Station until Friday.

NASA says it needs more time to prepare before sending two astronauts on a spacewalk to replace a broken pump on the station's cooling system. The pump failed over the weekend and knocked out half of the space station's cooling system, which keeps electronic equipment from overheating.

Managers had been hoping to do the first spacewalk on Thursday but decided workers on the ground needed more time to work on the repair plan. A second spacewalk will be conducted a few days later to complete the repairs.

NASA officials say the six astronauts at the space station are safe and the outpost is stable.