Spacewalk ends early

HOUSTON, May 20 (UPI) -- U.S. spacewalkers at the International Space Station completed the first step to repair a slow leak in a thermal control system cooling loop, NASA said Friday.

Endeavour mission specialists Drew Feustel and Greg Chamitoff installed an ammonia jumper cable that will connect cooling loops of the ISS's port 3 and 4 segments, the U.S. space agency said on its Web site.

NASA said the walk would end early because of the failure of a carbon dioxide sensor on Chamitoff's suit. The astronauts were told to delay removing a debris shield on the lab, Florida Today reported.

NASA said it is conservative in its estimates of time in space, and Chamitoff was in no danger.

During a second spacewalk, Feustel and mission specialist Mike Fincke will top off the ammonia in the port 6 photovoltaic thermal control system cooling loop, which has a slow ammonia leak.

Another major task is in the Destiny laboratory, where a wireless communications system antenna will be installed, NASA said.

The 16-day flight is the last for the Endeavour.