(CNN) – The International Space Station crew is preparing for a spacewalk to address the leak of ammonia from a cooling system, the commander said Friday.
NASA said the crew is preparing for a “possible” spacewalk and that a decision on whether to go ahead with it is likely to come late Friday.
Cmdr. Chris Hadfield of Canada announced the plan to venture outside the space station via his Twitter account.
“Good Morning, Earth! Big change in plans, spacewalk tomorrow, Chris Cassidy and Tom Marshburn are getting suits and airlock ready. Cool!” he posted Friday.
“The whole team is ticking like clockwork, readying for tomorrow,” he tweeted a short time later. “I am so proud to be Commander of this crew. Such great, capable, fun people.”
Cassidy and Marshburn are NASA astronauts. Hadfield, who is with the Canadian Space Agency, is aboard the space station as its commander.
Mission managers are discussing information on the leak that was gathered overnight, NASA said in a news release Friday.
Meanwhile, Cassidy and Marshburn worked in an airlock Friday to check out the U.S. spacesuits they will wear if a spacewalk is approved, NASA said, while Hadfield prepared for his role as choreographer of the spacewalk.
Cassidy and Marshburn have each done three spacewalks, all on a mission to the space station in 2009, NASA said. They collaborated on two of those spacewalks.
The six-man crew, which also includes three Russian cosmonauts, is not in danger from the leak, NASA said.
The leak was detected after the crew reported seeing small white flakes floating away from the station, NASA said Thursday in a news release.
NASA helped find the leak with external cameras while the crew used hand-held cameras pointed out of windows.
The leak is in a cooling loop in a solar array that has leaked before. NASA said crew members tried to fix a leak in November. It’s unclear whether this is the same leak or a new one.
The ammonia coolant for the power channel, one of eight used to supply electricity to the station, is likely to run out by late Friday morning and it will be shut down, NASA said.
It is devising a plan to reroute other power sources so that all systems remain fully operational.
Ammonia is used to cool each of the solar arrays that provide electricity to station systems, NASA said.
“It is a serious situation, but between crew and experts on the ground, it appears to have been stabilized. Tomorrow we find out for certain,” Hadfield tweeted Thursday.
Hadfield, Marshburn and Russian cosmonaut Roman Romanenko are scheduled to leave the station Monday at 7:08 p.m. ET.
Hadfield asked NASA on Thursday if the leak would affect the undocking.
Capsule Communicator Doug Wheelock said that officials at the Mission Control Center in Houston saw nothing they couldn’t overcome technically, but they would have more information in the morning.
Three crew members, Cassidy and Russian cosmonauts Alexander Misurkin and Pavel Vinogradov, will remain on the space station when the others leave.
They will be joined at the end of the month by three new crew members: NASA astronaut Karen Nyberg, Russian cosmonaut Fiyodor Yurchikhin and European Space Agency astronaut Luca Parmitano, who are due to launch aboard a Russian Soyuz spacecraft on May 28.
The space station is operating normally aside from the leak, NASA said.
