NASA is embarking on another spacewalk.<br/> <br />This time, it's to fix a failed pump valve that regulates the International Space Station's coolant system.<br/> <br />American flight engineers Rick Mastracchio and Mike Hopkins will be going on the first of three planned walks this Saturday.<br/> <br />NASA recreated the spacewalks on Earth and sent a video to the station so the astronauts can get their own preview.<br/> <br />During their first trip, they'll be tasked with de-integrating the failed pump valve and installing a jumper box.<br/> <br />The jumper box serves as a detour for ammonia to flow from the radiator as it cools electronic systems on the station.<br/> <br />Astronauts will remove the failed pump and begin installing a spare pump on the second and third walks.
