A Russian Soyuz spacecraft docked with the International Space Station took off leaking coolant early last month, sparking concerns about whether the vehicle would be safe to carry ISS crew members back to Earth.
NASA and the Russian space agency Roscosmos have now announced 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 an emergency option should the need arise.
Roscosmos will send a replacement Soyuz called MS-23 to the ISS, which will launch on February 20, so it can be used to return the astronauts to Earth. This mission was supposed to launch in March with new crew members, but will now launch earlier and with no crew.
NASA refers to the new Soyuz as a replacement vehicle, not a rescue, and emphasizes that the space station crew is safe. “We don’t call it a rescue Soyuz. At this point, the crew is safely aboard the space station,” Joel Montalbano, International Space Station program manager at NASA’s Johnson Space Center in Houston, said at a briefing. ‘The crew doesn’t have to come home immediately today. All systems work.”
An image of the damage to the docked Soyuz was obtained using the space station’s robotic arm, showing a hole through the Soyuz radiator and pipe supplying coolant. With coolant leaking from the system, it would be dangerous to fly in the vehicle as temperatures can reach high levels during a return trip to Earth.
“The biggest problem in landing the current Soyuz with the crew is the thermal conditions, because we lose the ability to deflect heat on the Soyuz,” explained Sergei Krikalev, executive director of Human Space Flight Programs at Roscosmos. at the briefing. Between crew members’ body heat, heat generated by equipment, and the heat created by friction as the vehicle travels through the atmosphere, temperatures in the crew and equipment compartments can reach unsafe levels.
When the new Soyuz arrives at the space station, the equipment is moved from the old vehicle to the new one. After that, the new Soyuz will be used to return the crew to Earth, and the old Soyuz will be landed as usual, but without a crew so it can be checked for damage and its effects on performance.
“The returning Soyuz will take some temperature readings to gauge how the vehicle is doing 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 back on Earth.”
There is also a 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 about the situation, but this is only a contingency plan and should not be necessary if the crew can travel on the new Soyuz.
As for the cause of the leak, Krikalev said their investigation showed it was not caused by a technology or manufacturing issue. This was a concern as this wasn’t the first time a Soyuz leak while docked to the ISS – a similar Soyuz leak occurred in 2018. At the time, Roscosmos said pretty bizarre claim that the leak could have been caused by tamper drilling rather than a manufacturing defect.
Many observers originally thought the latest leak might have been caused by a micrometeoroid impact, especially since it happened around the time of the Geminid meteor shower, when Earth passed through a field of debris in its orbit. An impact from a micrometeoroid still seems the most likely explanation for the damage, with Krikalev announcing that experiments showed similar damage caused by a particle about 1mm in diameter and traveling at 7 kilometers per second. However, this impact was not related to the meteor shower because the hole is in a different location than the direction the Geminids are coming from.
NASA says it will announce the precise dates for the coming months of scheduled flights in the coming weeks.