Human WorldSpaceflight

Replacement Soyuz to bring home stranded ISS crew

Replacement Soyuz: Modular spacecraft docked at ISS, Earth in background.
The Soyuz MS-22 crew ship pictured on October 8, 2022. It’s in the foreground, docked to the Rassvet module, as the International Space Station (ISS) orbited 264 miles (425 km) above Europe. A micrometeorid pierced the Soyuz MS-22 on December 15, 2022, causing a coolant leak. So, its 3-person crew is stranded at the ISS until a replacement Soyuz arrives in mid-February. Image via NASA.

Replacement Soyuz to bring home stranded ISS crew

The Russian space agency Roscosmos says it will launch the next scheduled Soyuz – an uncrewed mission – one month early. That’s so it can replace the leaking Soyuz capsule MS-22, currently docked at the International Space Station (ISS). That capsule carried three crew members to the ISS last September. But on December 15, 2022, a micrometeoroid – a tiny bit of rock in space – struck the MS-22. The particle pierced the capsule’s radiator, causing it to leak. So, the Soyuz capsule MS-22 has been out of action, its crew technically stranded until the replacement MS-23 arrives.

The stranded crew members are: Russian cosmonauts Sergey Prokopyev and Demitri Petelin, and American astronaut Frank Rubio.

MS-23 is scheduled to liftoff on February 20, 2023.

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Trio of ISS crew members have no ride home

Currently, there are seven people living in the International Space Station. And there are only four available seats to return home on the four-person SpaceX Dragon crew capsule currently docked at the ISS. So, the early launch of a Soyuz crew capsule isn’t a rescue mission, said NASA ISS program manager Joel Montalbano. He was speaking during a media briefing held Wednesday morning, January 11, 2023:

We’re not calling it a rescue Soyuz. Right now, the crew is safe on board the space station. We, by design, have a space station that’s protected as we can (make it).

The upcoming mission is not a rescue, because there is currently no threat to the safety of the marooned crew members. He said:

I’m calling it a replacement Soyuz. This is the next Soyuz that was scheduled to fly in March. It’ll just fly a little earlier. From that standpoint, that’s kind of what we’re looking at, but I’ll tell you there’s no immediate need for the crew to come home today that all the systems are operating.

The seven crew aboard the ISS make up Expedition 68, which is scheduled to end in March 2023.

Replacement Soyuz is the safest option

Sending up a replacement Soyuz capsule is the best option to ensure the crew’s well-being during re-entry, said Sergei Krikalev. He is the executive director for human spaceflight programs at Roscosmos.

He said techs and engineers at Roscosmos believe the MS-22 Soyuz will survive returning to Earth. But the environment inside it might prove overwhelming for any passengers. Krikalev described the danger:

If a crew would be there then the temperatures … could be in high 30s, maybe low 40 degrees centigrade. And temperature itself is not so high, but the problem is that in small volume, humidity can be high, and crew may overheat with high temperature and high humidity. That’s why we are not planning to use Soyuz in nominal situations for a good entry.

Roscosmos will be relying on the hardiness of its Soviet-era technology to see the capsule home in one piece:

Krikalev further explained:

As for re-entry, we expect that maybe we will have some overheating of equipment and still we think that Soyuz (has) several layers of redundancy, and if the computer fails, we have capability to continue re-entry mode in analog with analog equipment, so we have several layers of redundancy, so we think that Soyuz will return back safely.

15,660 mph meteor caused leak

After analyzing the leak that started December 15, Roscosmos and NASA believe a 1mm micrometeor caused the leak. Traveling at breakneck speed, the minuscule piece of debris pierced the Russian spacecraft, Krikalev said:

We still think that it’s a micrometeor hit because we have (an) image of the crater on (the) radiator. And we also made an experiment using (a) special high-velocity gun, and we did (an) experiment trying to hit an aluminum plate with the same structure with a small particle about 2 millimeters in diameter. And our result of this test completely coincides with our calculation, so our current theory is that this damage was caused by a small particle about 1 millimeter in diameter and velocity about 7 kilometers per second.

That means the tiny rock that hit the Soyuz was moving at around 15,660 mph (25,202 kph) relative to the ISS. The ISS orbits at a speedy 17,500 mph (28,000 kph) around the Earth.

No way home until March

With the MS-22 Soyuz no longer space-worthy, the trio it brought to orbit don’t have a safe way to get home in the event of an emergency. Should an evacuation situation arise, the three would have to try their luck with the damaged Soyuz.

Arrival of their safe ride home is still weeks away, with added delays once it arrives. Krikalev said:

Right now, we are planning to send it in (the) end of February, February 20th actually, and usually we need to have about a week for a crew handover and moving all equipment from one service (module) to another if needed. So at this point we also expect that we (will) prepare and learn to use (the replacement Soyuz for) a week or two after docking of new Soyuz.

Because the three stranded space travelers are an integrated crew, NASA and Roscosmos have put their heads together to find the best solution. For NASA, that meant finding out if SpaceX could help:

As a part of the analysis, NASA also reached out to SpaceX about its capability to return additional crew members aboard Dragon if needed in an emergency, although the primary focus is on understanding the post-leak capabilities of the Soyuz MS-22 spacecraft.

Bottom line: An uncrewed Soyuz capsule will fly to the ISS in February to provide a safe way home for a trio of temporarily stranded crew members.

January 12, 2023
Human World

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