On 4 May 2013 astronauts Chris Cassidy and Tom Marshburn left the warmth and atmosphere of the International Space Station to repair a leak of ammonia coolant from the ISS. During the 5 hour, 30 minute spacewalk Cassidy and Marshburn removed a pump controller box from the truss (the girderwork which forms the backbone of the station) and replaced it with a spare. Mission Control activated the new pump while the spacewalkers watched for any escaping ammonia “snowflakes” but there were no new signs of a leak.

Men at work in space. (Image credit: CSA/Chris Hadfield)

Men at work in space. (Image credit: CSA/Chris Hadfield)


The coolant leak had been detected two days earlier when external cameras showed snowflakes of leaking ammonia drifting around the station, prompting engineers and flight controllers to start planning the unscheduled spacewalk. Thanks to extensive training and consummate professionalism, the two astronauts successfully and without a fuss fixed the problem . The space station is now functioning normally.

This spacewalk was the 168th EVA in support of the assembly and maintenance of the ISS.

We don’t drive hover cars yet, we don’t live in silver domes and we don’t fly to work with jetpacks, but we live in a time when astronauts working in a vacuum where damage to your suit means a horrific death to repair a space station moving at nearly 28000 km/h, 410 km above the Earth’s surface is so routine nobody notices. Maybe the future is here at last.

(Article by Colin Johnston, Science Communicator)


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