Astronauts Take an Inpromptu Walk
May 13, 2013
National Aeronautics and Space Administration (NASA) astronauts Chris Cassidy and Thomas Marshburn took a five-hour spacewalk outside the International Space Station (ISS) on May 11 to repair a leak to the station’s cooling system. Numerous astronauts have taken similar spacewalks to repair or maintain the station.

Astronaut Chris Cassidy on a spacewalk outside the International Space Station on May 11, 2013. (NASA)
The ISS uses ammonia in its cooling systems. On May 9, astronauts noticed ammonia “snowflakes” floating in space just outside the space station. After a day of planning, astronauts left the safety of the space station to replace the faulty pump.
The International Space Station is an artificial Earth satellite operated by more than 15 nations—including the United States and Russia. The first part of the station was launched in 1998, and the first full-time crew—one American astronaut and two Russian cosmonauts—occupied the station in 2000. The ISS is the world’s longest continuously operated spacecraft.
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