NASA calls off spacewalk for second time this month

June 24 (UPI) -- NASA canceled a spacewalk for the second time this month on Monday after reporting a coolant leak on the umbilical unit on one of the astronaut's spacesuits.

Astronaut Tracy Caldwell Dyson reported the leak on the suit's servicing and cooling umbilical unit, or SCU, just before she and Mike Barratt were set to walk outside the International Space Station at about 8:52 a.m., EDT. Both astronauts had already turned on the internal power to their suits for what had been expected to be a 6.5-hour spacewalk.

NASA said Dyson and Barrat had opened the hatch to the space station's Quest airlock before reporting the water-leakage issue.

"The crew is working with ground controllers to repressurize the crew lock section of the airlock before returning inside the station's equipment lock," NASA said in its blog.

The astronauts returned inside the main space station in about an hour.

"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 NASA's mission control, according to Space.com.

Astronauts Butch Wilmore added on the NASA livestream,"It was a pretty impressive snowstorm."

On June 13 , NASA called off a spacewalk with Dyson and astronaut Mike Dominick when one of them experienced discomfort. NASA did not say which astronaut experienced the discomfort or give details about the issue.

The astronauts on that walk had expected to scrape microorganisms from the outside of the ISS to study for the possible origins of life.