Update for 10:23 p.m. EST: Russia's space agency Roscosmos has called off a spacewalk by two cosmonauts at the International Space Station today after an apparent coolant leak on a Soyuz MS-22 crew capsule spewed coolant around its docking port on the orbiting lab.
The leak was first detected at 7:45 p.m. EST (0045 Dec. 15 GMT) as cosmonauts Sergey Prokopyev and Dmitri Petelin were preparing to exit the space station for a 7-hour spacewalk outside the station. The Soyuz spacecraft launched to the space station on Sept. 21 to deliver the two cosmonauts and NASA astronaut Frank Rubio to the space station and was due to return to Earth size months later.
"The cause of this leak [is] not known at this time," NASA spokesperson Rob Navias said during live commentary. "Russian specialists are continuing to look at the data and discussing what may have triggered the leak."
This is a developing story and we'll share updates as they are available.
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Two cosmonauts will work outside the International Space Station (ISS) for about seven hours on Wednesday night (Dec. 14), and you can watch the action live.
Sergey Prokopyev, commander of the station's current Expedition 68 mission, and Dmitri Petelin are scheduled to begin a spacewalk Wednesday at 9:20 p.m. EST (0220 GMT on Dec. 15). You can watch live here at Space.com, courtesy of NASA, beginning at 9 p.m. EST (0200 GMT).
"The duo will exit the Poisk module's airlock and transfer a radiator from the Rassvet module, then connect it to the Nauka multipurpose laboratory module," NASA officials wrote in an update on Tuesday (Dec. 13).
This work is expected to take about seven hours.
Prokopyev and Petelin laid the groundwork for Wednesday night's extravehicular activity (EVA) with a 6.5-hour spacewalk on Nov. 17, during which they freed the radiator, readying it for relocation.
Relocation was supposed to happen on Nov. 25, but that spacewalk was canceled when Prokopyev noticed an issue with his Orlan spacesuit. That problem has apparently been solved.
Anna Kikina — like Prokopyev and Petelin, a cosmonaut with Russia's federal space agency Roscosmos — will assist during Wednesday night's EVA from inside the ISS. She will operate the 36-foot-long (11 meters) European robotic arm, which will help move the radiator.
Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us @Spacedotcom, Facebook and Instagram.