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ISS astronauts checked for toxic ammonia contamination during spacewalk

Glover and Hopkins working outside the ISS during their spacewalk on March 13, 2021
Glover and Hopkins working outside the ISS during their spacewalk on March 13, 2021 NASA TV

NASA astronauts Victor Glover and Mike Hopkins had to be checked for ammonia contamination during a spacewalk outside the International Space Station (ISS) on Saturday, March 13. They could have gotten the toxic chemical on their spacesuits during a procedure to vent the station’s external cooling system, as reported by AP.

The cooling system is needed to control temperatures of the side of the station which faces the sun. Without the cooling system, temperatures on the outside would get as high as 250°F (121°C). The system uses liquid ammonia which is pumped through pipes to keep the temperature stable as part of the Active Thermal Control System.

About an hour into today’s spacewalk, the astronauts were venting the ammonia from part of the system before relocating a jumper line. Both Hopkins and Glover were near to the hose when it was disconnected, and ammonia flakes came out of the system. “Oh yeah, look at that go,” Hopper said as the venting began. Although control and the astronauts knew some frozen flakes of ammonia would be released, more came out of the hose than was expected, which was why extra safety precautions were needed.

Around 10 minutes after the venting, mission control called for a pause and checked in with the astronauts about how much ammonia had come out. “I felt like it was more than I was expecting,” Hopkins told mission controllers. Although most of the ammonia came out away from the station and he estimated that there were less than 30 flakes, he did think some had contacted the visor of his helmet.

Mission control concurred. “From our camera views down here we did see what looked like propulsive movement of the flakes, so we’re going to go ahead and be conservative and call that a suspected case [of contamination],” they said.

A visual check showed the astronauts’ suits were clear of ammonia crystals, and they will also check for ammonia crystals in the airlock once the spacewalk is complete. The extra care is necessary because the team wanted to make sure that no ammonia is brought inside the station, as it is corrosive and can be an irritant to the eyes and lungs.

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Georgina Torbet
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
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