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Stranded ISS astronauts are getting a new Soyuz to ride home

The coolant-deprived vessel that got them there will return to Earth alone

Russian space agency Roscosmos has decided to send another Soyuz capsule to the International Space Station to rescue crew stranded by a coolant leak in their return ride. 

The leak in the Soyuz MS-22 craft's coolant system was caused by a micrometeor and was noticed ahead of a planned mid-December spacewalk that was canceled to address the problem. 

Roscosmos said it was no longer able to ferry crew back to Earth via the craft, as the coolant lost was used to keep the internal cabin of the capsule cool enough to keep astronauts alive during reentry.

"Having analyzed the condition of the spacecraft, thermal calculations and technical documentation, it has been concluded that the MS-22 must be landed without a crew on board," Roscosmos director Yuri Borisov said Wednesday.

NASA confirmed the plans in a briefing this morning.

MS-23, the next Soyuz launch that was scheduled for mid-March and would have brought three new crew members to the ISS, will now head to the station unmanned to ferry cosmonauts Sergey Prokopyev and Dmitry Petelin and NASA astronaut Francisco Rubio, who have been at the station since September, back to Earth.

Micrometeoroids like the one that struck MS-22 are tiny, just like the coolant hole they made in the capsule. Often less than a single millimeter across, they still have an impact velocity of 10km/s, or 6.2 miles/sec - enough to cause visible punctures. 

Since its launch last year, the James Webb Space Telescope has suffered 14 measurable micrometeoroid hits to its primary mirror, and it's orbiting one million miles from Earth in the middle of space. 

Earth's orbit is far more crowded with debris – both natural and man made – than JWST's Lagrange point 2, meaning impacts are pretty common. 

No more emergencies, please

When spacecraft take crew to the ISS a careful balance is maintained ensuring there are the same number of seats as crew in case of an emergency evacuation. That hasn't been the case since the micrometeor strike that bled all of MS-22's coolant into space last month.

In case such an accident happens between now and February 20, when MS-23 is scheduled to launch, MS-22 is going to have to serve as a lifeboat for Prokopyev, Petelin and Rubio, as the other craft docked at the station, a SpaceX Dragon capsule, doesn't have extra seats. 

Also onboard the ISS are four astronauts from SpaceX's Crew-5, which docked in October. 

With it already having a craft at the space station, NASA reportedly turned to SpaceX in the immediate aftermath of the coolant leak to see if it could provide a ride to the stranded MS-22 crew, but circumstances made the possibility unlikely.

Along with not having enough seats, SpaceX Dragon capsules require astronauts to wear one of SpaceX's tailored spacesuits, and the Soyuz crew doesn't have a set. 

While it's set to take off February 20, it's unclear when the MS-22 crew will return to Earth in their new ride. 

The MS-22 mission was planned to last 188 days from September 21, 2022, when it launched, meaning the crew was originally supposed to return in late March, shortly after the MS-23 crew would have arrived. 

Now, according to Roscosmos, "The expedition of Sergey Prokopyev, Dmitry Petelin and Francisco Rubio to the ISS is being extended." How long that may be wasn't mentioned. ®

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