Unpiloted Soyuz spacecraft docks at space station to replace damaged crew capsule

The Soyuz MS-23 spacecraft closes in for docking Saturday night at the International Space Station. Credit: NASA TV / Spaceflight Now

A replacement for a damaged Russian Soyuz crew ferry spacecraft docked at the International Space Station Saturday night, two days after launching from Kazakhstan on a mission to give two Russian cosmonauts and a NASA astronaut a ride back to Earth later this year.

The Soyuz MS-23 spacecraft linked up with the Poisk module, located on the space-facing side of the Russian Zvezda service module, at 7:58 p.m. EST Saturday (0058 GMT Sunday) to close out a radar-guided automated rendezvous and docking.

The human-rated crew capsule flew to the station without anyone on-board, an unusual step for Russia’s space program, to replace a damaged Soyuz spacecraft that was supposed to bring home Russian commander Sergey Prokopyev, cosmonaut Dmitri Petelin, and NASA astronaut Frank Rubio next month.

But the Soyuz that launched Prokopyev’s crew in September sprung a coolant leak Dec. 14, spewing frozen flakes of fluid from its radiator into space after what Russian officials determined was likely an impact from a tiny fragment of rock from deep space, called a micrometeoroid.

Russian space officials decided to move forward the launch of the next Soyuz spacecraft by a month to late February to replace the damaged Soyuz MS-22 spacecraft. Russian engineers deemed the damaged Soyuz MS-22 vehicle safe enough to use, if needed, for an emergency evacuation of the space station, but not for a regularly-scheduled undocking and landing. Officials were concerned about overheating of avionics and other internal components of the Soyuz MS-22 spacecraft, with its disabled cooling system.

Prokopyev, Petelin, and Rubio had their six-month expedition on the space station extended to last more than a year. Instead of returning on the damaged Soyuz MS-22 spacecraft in late March, they will re-enter the atmosphere and land in Kazakhstan aboard the newly-arrived Soyuz MS-23 spacecraft in September, following the launch of the next Soyuz crew to take their place on the orbiting outpost.

With the docking of the Soyuz MS-23 spacecraft Saturday night, the station crew members planned to transfer custom-fitted seat liners from the damaged Soyuz and SpaceX’s Dragon Endurance crew ferry ships docked at other ports on the station. Since the coolant leak on Soyuz MS-22 and before the arrival of Soyuz MS-23, Rubio would have flown back to Earth with four other astronauts on the SpaceX crew capsule, if the station crew needed to abandon the station in the event of an emergency.

The damaged Soyuz MS-22 spacecraft will depart the station and head for a parachute-assisted landing on the Kazakh steppe next month without anyone on-board.

Russian ground controllers detected a similar coolant leak from an unpiloted Progress cargo freighter docked at the station Feb. 11.

The coolant leaks on the Soyuz MS-22 and Progress MS-21 spacecraft were unlike anything that has happened in the more than 25-year history of the space station. After the leak on the Progress cargo freighter earlier his month, it’s not clear if Roscosmos officials still believe the micrometeoroid explanation for the Soyuz MS-22 leak.

Russia’s space agency, Roscosmos, posted an update on its Telegram channel Tuesday, claiming the preliminary conclusion of the investigation into the damage to the Progress MS-21 supply ship indicated it was caused by an “external influence,” and not a manufacturing defect.

Dana Weigel, NASA’s deputy program manager for the ISS, said Tuesday that the U.S. space agency is also analyzing data to find the cause of the leaks.

She told reporters she did not interpret the Russian space agency’s statement about an “external influence” on Progress MS-21 as specifically pointing to micrometeoroid damage.

“I actually don’t interpret that was micrometeoroid damage over the spacecraft,” Weigel said, referring to the Roscosmos statement on Progress MS-21. “I think what they’re really trying to understand is are there any signs or signatures that somewhere along the spacecraft’s journey, whether it’s launch or launch vehicle separation, there’s some other external influence or damage that could have occurred that could have been a factor there.”

The docking of Soyuz MS-23 at the station Saturday night clears the way for launch of another SpaceX crew mission from NASA’s Kennedy Space Center in Florida early Monday. A four-man crew commanded by NASA astronaut Stephen Bowen will head to the space station for a six-month expedition, replacing an outgoing team of four astronauts scheduled to return to Earth in early March on a different SpaceX crew capsule.

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