Crew-5 Home Safe and Sound While Questions Remain About Russian Coolant Leaks

Four astronauts on SpaceX’s Crew Dragon Endurance returned to Earth tonight. NASA astronauts Nicole Mann and Josh Cassada, Japanese astronaut Koichi Wakata, and Russian cosmonaut Anna Kikina splashed down in the Gulf of Mexico. Meanwhile, questions remain about why two Russian spacecraft docked to ISS experienced coolant leaks in December and February and whether a common manufacturing defect may be responsible.

The four members of Crew-5 splashed down near Tampa, FL at 9:02 pm ET tonight after 157 days in space.

 

Splashdown of Dragon confirmed – welcome back to Earth, @AstroDuke, @Astro_Josh, @Astro_Wakata, and Anna! pic.twitter.com/LHrrqL5g6U

— SpaceX (@SpaceX) March 12, 2023

It was an eventful mission. On top of the more than 200 scientific experiments and five spacewalks they conducted, they witnessed two Russian spacecraft docked to the ISS, Soyuz MS-22 and Progress MS-21, experienced worrisome coolant leaks.

Their colleagues who arrived on Soyuz MS-22, NASA astronaut Frank Rubio and Roscosmos cosmonauts Sergey Prokopyev and Dmitri Petelin, should have returned home themselves by now, but their mission has been extended for several months because Soyuz MS-22 is not considered safe to bring them back to Earth.

Instead, Russia launched the Soyuz MS-23 empty instead of bringing up their replacements, Russian cosmonauts Oleg Kononenko and Nikolai Chub and NASA astronaut Loral O’Hara.

For several weeks between the Soyuz MS-22 loss of coolant and the arrival of Soyuz MS-23, contingency plans were in place for Rubio to return to Earth along with Crew-5. His customized seat liner was moved from Soyuz MS-22 to Endurance in case an emergency evacuation was needed before Soyuz MS-23 arrived.

Fortunately that wasn’t necessary and Rubio remains aboard ISS. At the moment, Rubio, Prokopyev and Petelin are to return in Soyuz MS-23 in September after Kononenko, Chub, and O’Hara arrive on Soyuz MS-24.

Roscosmos and NASA concluded the Soyuz MS-22 coolant leak was most likely caused by a micrometeoroid impact and the Progress MS-21 leak by an external impact.  Soyuz and Progress are very similar in design — Soyuz is for crews, Progress for cargo — and they ruled out a common manufacturing defect that might affect future spacecraft.

Yesterday, however, Russia’s news agency TASS, citing another official Russian news outlet, Izvestiya, reported that Russian experts are questioning whether a production defect might, in fact, be the cause and Soyuz MS-23 might similarly be affected. Those reports assert that the Soyuz MS-24 launch will be moved up to June to accelerate the crew exchange in case Soyuz MS-23 has the same defect.

2/3. According to the sources of Izvestia, some Roscosmos specialists don’t exclude the possibility of a manufacturing defect in the cooling system of Soyuz-MS 22 and Progress MS-21. So they insist on the earlier return of Soyuz MS-23 in case if it has the same defect.

— Katya Pavlushchenko (@katlinegrey) March 10, 2023

Asked about those reports this evening in a post-splashdown media teleconference, NASA ISS Program Manager Joel Montalbano said Roscosmos and spacecraft manfacturer Energia continue to look at “everything, all the possibilities.” NASA remains confident in the safety of Soyuz MS-23 “but we’re always looking.”  As far as he knows, however, the Prokopyev-Petelin-Rubio crew is still scheduled to return in September, though Roscosmos continues to review the schedule.

The concern is that without the coolant, the interior of Soyuz MS-22 would be too hot for three crew members, who generate their own heat and humidity, making it not only very uncomfortable for them but potentially affecting computers and other electronics.  Montalbano confirmed that Roscosmos is planning a thermal loading test in coming days with three Russians — Prokopyev, Petelin and Andrey Fedyaev who just arrived on Crew-6 — inside the Soyuz MS-22, which is still docked there.  It will undock and return to Earth empty soon.