A Russian Soyuz spacecraft docked to the International Space Station (ISS) began Refrigerant leak early last month, raising concerns about whether the vehicle would be safe to transport ISS crew members back to Earth.
NASA and the Russian space agency Roscosmos have now announced that they will send a replacement spacecraft for NASA astronaut Frank Rubio and Roscosmos cosmonauts Sergey Prokopyev and Dmitry Petelin to travel home. A SpaceX Crew Dragon is also available as a contingency option should the need arise.
Roscosmos will send a replacement Soyuz called the MS-23 to the ISS, launching on February 20 so it can be used to return astronauts to Earth. This mission was scheduled to launch in March with new crew members, but will now launch earlier and without a crew.
NASA refers to the new Soyuz as a replacement vehicle, not a rescue vehicle, and emphasizes that the space station crew is safe. “We don’t call it a rescue Soyuz. At this time, the crew is safe on board the space station,” Joel Montalbano, International Space Station program manager at NASA Johnson Space Center in Houston, said at a briefing. “There is no immediate need for the crew to return home today. All systems are working.”
An image of the damage to the docked Soyuz was obtained using the space station’s robotic arm, showing there is a hole through the Soyuz’s radiator, as well as the pipe that supplies coolant. With refrigerant leaking from the system, it would be dangerous to fly the vehicle, as temperatures could reach high levels during a return trip to Earth.
“The main problem in landing the current Soyuz with the crew would be the thermal conditions because we lost the heat rejection capability on the Soyuz,” Sergei Krikalev, executive director of Roscosmos Human Spaceflight Programs, explained at the briefing. Between the body heat of crew members, heat generated by equipment, and heat caused by friction as the vehicle travels through the atmosphere, temperatures in the crew and equipment compartments could reach levels dangerous.
When the new Soyuz arrives at the space station, the team will move from the old vehicle to the new one. The new Soyuz will then be used to bring the crew back to Earth, and the old Soyuz will land as usual, but without a crew, so that damage and its effects on performance can be checked.
“The returning Soyuz will take some temperature measurements to know how the vehicle performs in this scenario, so that if we ever have a need in the future, we’ll have some additional data,” Montalbano said. “So we’re going to use this vehicle fully until it lands on Earth.”
There is also the possibility that SpaceX will use its currently docked Crew-5 Crew Dragon vehicle as a backup to return astronauts to Earth if necessary. NASA says it is in contact with SpaceX regarding the situation, but this is just a contingency plan and shouldn’t be necessary if the crew can travel on the new Soyuz.
As for the cause of the leak, Krikalev said that his investigation revealed that it was not caused by a technological or manufacturing problem. This had been a concern as it was not the first time a Soyuz had leaked while docked to the ISS; a similar Soyuz leak occurred in 2018. At the time, Roscosmos rather strangely asserted that the leak could have been caused by tamper drilling rather than a manufacturing defect.
Many observers originally thought that the latest leak might have been caused by a micrometeor impact, particularly since it occurred around the time of the Geminid meteor shower when Earth passes through a debris field in its orbit. A micrometeoroid impact still seems the most likely explanation for the damage, and Krikalev announced that experiments showed similar damage caused by a particle about 1 mm in diameter and traveling at 7 kilometers per second. However, this impact was unrelated to meteor shower since the hole is in a different location from the direction the Geminids are coming from.
NASA says it will announce the precise dates for the next few months of planned flights in the coming weeks.
