Soyuz MS-23
The Soyuz MS-23 spacecraft approaching the International Space Station Feb. 25. Credit: NASA TV

WASHINGTON — An uncrewed Soyuz spacecraft launched to replace a damaged Soyuz arrived at the International Space Station Feb. 25.

The Soyuz MS-23 spacecraft docked with the station’s Poisk module at 7:58 p.m. Eastern, a few minutes ahead of schedule. The spacecraft had launched two days earlier on a Soyuz-2.1a rocket from the Baikonur Cosmodrome in Kazakhstan. Instead of a crew, it carried about 430 kilograms of cargo to the station.

Soyuz MS-23 was originally to launch a replacement crew of two Russian cosmonauts and one American astronaut to the station in March. Those plans changed after the Soyuz MS-22 spacecraft docked to the station experienced a coolant leak in mid-December that Roscosmos later concluded made it infeasible for it to return the crew to Earth as originally planned.

Roscosmos and NASA announced in January that Soyuz MS-23 would launch without a crew in February. It would replace Soyuz MS-22, which will return to Earth without a crew in March. That will keep the original Soyuz MS-22 crew of Sergey Prokopyev, Dmitri Petelin and Frank Rubio on the station for several additional months. Roscosmos said Feb. 25 they expected the trio, originally set to return on Soyuz MS-22 in March after six months on the station, to instead come back in September on Soyuz MS-23.

Roscosmos blamed the Soyuz MS-22 leak on a micrometeoroid impact, a finding that NASA accepted in January when the agencies announced their decision to launch Soyuz MS-23 without a crew. However, another coolant leak on the Progress MS-21 cargo spacecraft docked to the station Feb. 11 prompted new questions about that explanation, particularly after Roscosmos said “external influences” appeared to cause the Progress leak.

“It’s still an ongoing assessment. They’re still taking a really close look at all of the information they have on spacecraft to try and understand if there’s any common cause or anything else that could have been a causal factor in having those two radiator panels leak,” said Dana Weigel, NASA ISS deputy program manager, at a briefing a few hours after the docking to discuss the upcoming Crew-6 mission to the station.

She added that Roscosmos was sharing information with NASA. That investigation is limited to telemetry from the spacecraft and external observations by cameras on the ISS, since the service module of the Progress and Soyuz spacecraft, where the leaks occurred, does not return to Earth. “When you have a situation like that, it tends to take a bit longer to assess and look through everything.”

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...