A coolant leak on the International Space Station may require astronauts to go on a spacewalk Saturday to survey the problem. NASA

Astronauts will be taking a spacewalk this weekend to get a better look at an ammonia leak on the International Space Station.

Basically, it’s like going out to fix your car's leaky radiator at 230 miles above the Earth, while you and the car are being whipped around at more than 17,200 miles per hour.

The station’s commander, Canadian astronaut Chris Hadfield, first reported an ammonia leak on Thursday morning after seeing a steam of white flakes floating away from the port side of the station. The ISS uses ammonia to cool the power channels that direct electricity to the station’s systems, and each array of solar panels has its own cooling loop.

This leak is on a cooling loop that has experienced some trouble before. Seepage was first noticed in 2007, and in 2011, the astronauts added ammonia to the loop to replace what was lost. The crew took a spacewalk in November 2012 to assess that leak, and it’s still unclear if this is the same exact spot that plagued the crew previously. In the meantime, the crew in orbit and on the ground is working on a plant to reroute other power channels in order to keep all systems operational.

“The station continues to operate normally otherwise and the crew is in no danger,” NASA said.

The current plan is for astronauts Chris Cassidy and Tom Marshburn to perform a spacewalk on Saturday to look for the source of the coolant leak, and possibly make repairs. Commander Hadfield will act as the “intravehicular” crew member that choreographs the spacewalk. Cassidy and Marshburn have each gone on three previous spacewalks in 2009, two of those with each other.

Commander Hadfield remains upbeat.

“The whole team is ticking like clockwork, readying for tomorrow,” he tweeted on Friday morning. “I am so proud to be Commander of this crew. Such great, capable, fun people.”

It’s not yet known how this last-minute problem will affect the planned shift change at the ISS later this month. Hadfield, Marshburn and Russian cosmonaut Roman Romanenko are scheduled to depart the station on a Soyuz capsule Monday, May 13. On May 28, another Soyuz capsule will blast off with three crew members to bring the station back up to its full strength of six: NASA astronaut Karen Nyberg, European Space Agency astronaut Luca Parmitano and Russian cosmonaut Fyodor Yurchikhin.

Coolant leaks were a problem for Russia’s Mir station as well. Mir was an aging space station in the late 1990s, and suffered antifreeze leaks from time to time. Russian officials told the press the leaks posed no danger to the crew aboard, but American astronaut Jerry Linenger said he could detect a “distinct, burnt-dry smell” in the station’s airlock.

Linenger, the crew physician, was also considered about the health effects of the coolant leaks.

Recognizing that some of his fans on Earth might be worried, on Thursday night Commander Hadfield tweeted a lovely panoramic picture from his position perched above the globe:

“A view to put the mind at ease,” Hadfield said.