Two cosmonauts were forced to abort their planned spacewalk on Wednesday after Russian flight controllers noted a significant coolant system leak in the Soyuz MS-22/68S spacecraft docked at the International Space Station. NASA television cameras showed a torrent of white flakes streaming away into space, appearing to originate near the aft instrumentation and propulsion module of the Soyuz spacecraft that carried Sergey Prokopyev, Dmitri Petelin and their crew. The cosmonauts were in the process of prepping for the spacewalk when the leak was discovered. Flight controllers immediately moved to abort the mission and the cosmonauts returned to the airlock. The cause of the leak is still unknown, but Russian officials have said that the crew is safe and all other systems on the Soyuz are working normally. The cosmonauts will remain on board the ISS while the leak is investigated and repairs are made. In the meantime, the spacewalk will be rescheduled for a later date. The mission was intended to conduct maintenance on the exterior of the station, but it is unclear if the leak will delay those activities.