Progress MS-21 Departs ISS As Russia Sets Launch Date for Soyuz MS-23

Russian engineers got a better look at the radiator on the Progress MS-21 cargo spacecraft last night as it departed the International Space Station and saw no damage. After rechecking the radiator on Soyuz MS-23, which is awaiting launch at the Baikonur Cosmodrome, Roscosmos said today it is recommending launch on February 23 EST (February 24 Moscow Time). Soyuz MS-23 will not have anyone aboard on the way to ISS. It is replacing Soyuz MS-22, which had its own coolant leak two months ago, and will bring the Russian-American MS-22 crew home later this year.

After Progress MS-21 undocked from the ISS at 9:26 pm EST last night (5:26 am this morning Moscow Time), cosmonauts commanded it to rotate 180 degrees so they could get a better look at the area where the coolant loop in the radiator depressurized and leaked on Saturday.

Roscosmos posted on Telegram that “no visual damage was detected.” The plan had been to deorbit the spacecraft one orbit later, but Roscosmos decided to delay that while they considered the option of returning to the ISS and docking at a different port for further inspections. Ultimately the decision was not to do that and Progress MS-21 will be deorbited later today, February 18. The deorbit command is scheduled for 10:15 pm EST (6:15 am February 19 Moscow Time), with reentry over the Pacific Ocean expected 42 minutes later.

Progress MS-21 is the second Russian spacecraft in two months to suffer a coolant leak. Soyuz MS-22 was first, on December 14, 2022 EST (December 15 Moscow Time). Progress and Soyuz have similar designs. Progress is for cargo, Soyuz for crews. Both have been launched for decades and these are the first known coolant leaks for either.

Soyuz MS-22 transported Russian cosmonauts Sergey Prokopyev and Dmitri Petelin and U.S. astronaut Frank Rubio to ISS in September 2022 and was intended to bring them home next month. Roscosmos and NASA do not consider Soyuz MS-22 safe for human travel except in an emergency, however, and Soyuz MS-23 is being launched empty as its replacement. The three people (two Russians and an American) who were supposed to launch on Soyuz MS-23 will have to wait for MS-24.

Roscosmos and NASA concluded the most likely cause of the Soyuz MS-22 coolant leak was a micrometeoroid impact. But with a second leak in just two months, engineers need to make sure there is no common design or manufacturing defect that could also affect Soyuz MS-23, so that launch was delayed.

Today, Roscosmos said the radiator on Soyuz MS-23 has been inspected and checked out OK. The Council of Chief Designers is recommending to the State Commission that launch take place on February 23 at 7:34 pm EST (February 24, 3:34 am Moscow Time).

Today, in RKK “Energia” passed the council of chief designers dedicated to the launch of the unmanned ship “Soyuz MS-23” to the International Space Station.

After depressurization of the thermoregulatory system of the cargo ship “Progress MC-21”, which occurred on February 11 at the ISS, the specialists of Roscosmos carefully analyzed the received telemetric information and images of the outer surface of the ship. They also examined in detail the radiator on the ship “Soyuz MS-23”, which was located in the assembly-testing body of the 254th Baikonur site, and did not find any damage on it.

As a result, the council of chief designers recommended the state commission to appoint the launch of the Soyuz MS-23 spacecraft with the Soyuz-2.1a rocket from Baikonur on February 24 at 03:34 Moscow time. [Translation via Google Translate]

Roscosmos and NASA are eager to get Soyuz MS-23 docked to ISS. Soyuz spacecraft not only ferry crews to and from the space station but serve as lifeboats in an emergency such as a depressurization or fire. Soyuz MS-22 has been declared unsuitable to take three people back to Earth because all the coolant that regulates temperature and humidity inside the spacecraft is gone. Not only would it be very uncomfortable for the crew, computers and other electronics could be affected.

The two space agencies have a contingency plan in the unlikely event something happens before Soyuz MS-23 arrives, but they hope not to have to use it. Rubio would bunk in with Crew-5, the four person American/Japanese/Russian crew using SpaceX’s Crew Dragon. There’s plenty of room and consumables for him, but no seat. His customized seat liner has been moved over there from Soyuz and securely attached in an area that actually was designed for additional crew members, but is used by NASA for cargo. Prokopyev and Petelin would return in Soyuz MS-22 despite its thermal malfunction on the premise that the heat load could be manageable with only two instead of three people aboard.

NASA did not respond to a request for comment today about Roscosmos’s plan and has not posted the new launch date on its ISS blog as of press time.

NASA refers to Progress spacecraft based on how many have resupplied the ISS. Progress MS-21 is the 82nd Progress to visit ISS and hence Progress 82 or 82P to NASA, but dozens were launched before that to support the Soviet Salyut 6 space station and its Salyut 7 and Mir successors. The first Progress was launched in 1978.

NASA held a media teleconference yesterday to discuss a different mission — the Crew Flight Test of Boeing’s Starliner commercial crew system planned for April — and said they would answer questions about the situation with Progress and Soyuz during a media teleconference on Tuesday, February 21, following the Flight Readiness Review for Crew-6.  Crew-6 is scheduled for launch on February 26.

The U.S.-Russian-European-Japanese-Canadian ISS has been permanently occupied by international crews rotating on roughly 4-6 month shifts for more than 22 years.