NASA Preparing Astronauts for Spacewalks

International Space Station crew members Doug Wheelock and Tracy Caldwell Dyson have now been scheduled to perform two spacewalks beginning Saturday to fix a pump module cooling system that dramatically failed last week and sounding repeated alarms awaking astronauts and cosmonauts from sleep time.

NASA has indicated a second spacewalk is now being planned for Wednesday to complete the job of swapping out the pump with one of four spares on board the ISS. The previously scheduled spacewalks have been delayed to enable the emergency repairs by Wheelock and Dyson.

The timing and procedures are being worked out by the team at NASA's Neutral Buoyancy Laboratory (NBL) in Texas with astronauts Robert Satcher Jr. and Rick Sturckow (above) conducting mock spacewalks. The underwater astronauts are identifying challenges that will need to be addressed when two of the six Expedition 24 astronauts perform the first of two planned spacewalks to replace a failed ammonia pump module.