Astronauts making a rare, hastily planned spacewalk replaced a pump outside the International Space Station on Saturday in the hope of plugging a serious ammonia leak.
The prospects of success grew as the minutes passed and no frozen flecks of ammonia appeared. Mission control said it appeared as though the leak may have been plugged, although additional monitoring over the coming days, if not weeks, will be needed before declaring a victory.
"No evidence of any ammonia leakage whatsoever. We have an airtight system – at the moment," mission control reported.