NASA cancels ISS spacewalk due to spacesuit coolant leak (video)

NASA cancelled a spacewalk at the International Space Station today (June 24) following a spacesuit coolant leak in the hatch.

NASA astronauts Tracy Caldwell Dyson and Mike Barratt were told by Mission Control at 8:52 a.m. EDT (1252 GMT) to stop the planned 6.5-hour spacewalk outside the International Space Station (ISS). The pair had already switched over to the internal power in their suits at 8:46 a.m. (1246 GMT), meaning the spacewalk had technically started. Following the cancellation, astronauts opened the hatch into the ISS at 9:51 a.m. EDT (1351 GMT), officially ending the spacewalk. 

While being broadcast on a NASA Television livestream, they had reported "literally water everywhere" as they were moving their suits to internal power to prepare for the extravehicular activity. The leak appeared to be coming from a servicing and cooling umbilical (SCU) on Dyson's spacesuit, she reported. While the situation was serious, the astronauts were not in any danger due to the leak. 

NASA issued a brief official statement following the cancellation, adding that additional information will follow on the agency's ISS blog. They made the call to cancel as it was unclear how much water was left in Dyson's suit following the leak, as a precautionary measure, officials added on NASA Television.

"I could see the ice crystals were flowing out there, and then, just like a snow machine, there was ice forming at that port on the SCU," Dyson told Mission Control. The SCU is designed to connect to the ISS airlock as astronauts are in the hatch preparing for the final stages of disconnecting for the EVA. They were still in the hatch when the leak happened, with the external door open, but closed it moments after the spacewalk was terminated. "It was a pretty impressive snowstorm," astronaut Butch Wilmore said during NASA's livestream.

This is the second time this particular spacewalk was postponed, after a June 13 attempt with a different astronaut group (Matt Dominick and Tracy Dyson) was postponed due to a "spacesuit discomfort" issue with Matt Dominick. A July 2 spacewalk is supposed to happen as well, but it is unclear if that will go ahead under these circumstances.

The total length of the spacewalk was 31 minutes, based on the time that elapsed between switching the suits to internal power and repressurizing the crew airlock. That brings Tracy Dyson's total EVA time to 23 hours and 20 minutes across four spacewalks, and Mike Barratt's total time to 5 hours and 37 minutes across three EVAs.

Related: NASA calls off spacewalk at International Space Station due to 'spacesuit discomfort'

The spacewalk had been running slightly behind its expected beginning at 8 a.m. EDT (1200 GMT) due to some small issues with tethers and other matters, but that was within normal range until the duo reported ice crystals (water) coming from the spacesuit.

"The spacewalk for today has been canceled due to a space suit cooling unit water loop leak that began right after the suits were put on internal battery power," an announcer on NASA Television said shortly after the spacewalk was canceled. "The crew is now moving back into the airlock and closing ... the hatch, then they will begin the repressurization process."

Conditions were frosty inside the hatch during repressurization. "It's a little snowy in here, but not as bad as it was ... I have ice on my gloves still and on my helmet a little bit," Dyson said.

Dyson added later she would remain on spacesuit battery power, as she was worried about the water leak affecting the umbilical connectors to the ISS. Mission Control told her there likely would not be an issue, but said she could remain on battery power if she liked.

The spacewalk was supposed to pick up faulty communications equipment, called a radio frequency group, and Dyson was expected to swab the ISS exterior to gather evidence of microorganisms in extreme microgravity environments. 

Monday's EVA was meant to be the first of two upcoming spacewalks geared toward ongoing science and maintenance of the orbital laboratory. (NASA originally planned three, but now plans on doing only two after the June 13 attempt.)

Coolant leaks have plagued planned spacewalks multiple times in recent years. In March 2022, water was found in an astronaut's helmet following an EVA, prompting a seven-month pause in spacewalks. And in 2013, Italian astronaut Luca Parmitano's helmet terrifyingly filled with water during an EVA.

This story was updated at 10:29 a.m. EDT with information about the water capacity in Dyson's suit.