Leak aboard the ISS: how astronauts will return to Earth

On February 11, specialists from the Moscow Region Mission Control Center, based on telematics data,

received automatically fromThe International Space Station (ISS) recorded a depressurization on the Progress MS-21 cargo ship docked to the Poisk module. Its cause, according to Roskosmos, is a coolant leak from the ship's cooling circuit.

Sergey Krikalev, executive director for manned space programs at Roscosmos, comments on the incident. Video: Roscosmos

The accident on the cargo "Progress MS-21" followedfor a similar incident on the Russian manned spacecraft Soyuz MS-22. On December 15, 2022, a significant external coolant leak occurred from the tail section of this spacecraft docked to the Rassvet module of the ISS.

What is this spaceship?

"Progress MS-21" - unmanned spacea transport ship that is used to deliver cargo to the ISS. The ships of this series are launched into orbit by the Soyuz-2.1a launch vehicle. "Progress" is used to supply the crew of the ISS and can lift up to 2.5 tons of payload. These could be crew products, equipment for scientific experiments, and even small satellites.

"Progress MS-21" was launched from the cosmodromeOn October 26, 2022, Baikonur successfully reached the ISS and docked with the Poisk module two days later. The ship delivered to the station 702 kg of fuel for refueling, 420 kg of drinking water, 41 kg of nitrogen and 1,357 kg of various equipment and materials. Among them, for example, fresh food, medical and sanitary products for the crew, equipment for 3D printing on board and much more.

Progress MS-21 after docking with the Poisk module. Image: NASA

The ships of this series are disposable:after cargo is delivered to the ISS, it is filled with garbage that must be disposed of. The loaded "Progress" deorbits and burns up in the Earth's atmosphere. The trajectory is chosen so that unburned objects land in the non-navigable South Pacific.

According to Roskosmos, cargo from the shipProgress MS-21 was postponed in early January, and in early February the crew was filling the module with debris and preparing for undocking, which was scheduled for February 18. It is not yet known if the target date will change due to an investigation into the incident.

Cosmonaut Anna Kikina transfers old equipment that needs to be disposed of to Progress MS-21. Photo: Roscosmos

What happened at Progress?

The analysis carried out by Roskosmos confirmed thatthat a fluid leak from the cooling system led to a depressurization on a cargo ship. A similar problem was previously recorded on the Soyuz MS-22 passenger manned spacecraft. In that case, the experts decided that the violation of the outer skin of the ship indicates a meteorite hit.

A hole from the December collision with a micrometeorite on the skin of the Soyuz MS-22 spacecraft. Photo: Roscosmos

Preliminary representatives of Roskosmosit was assumed that the cause of the new leak was also an external influence, which led to a violation of the integrity of the cargo ship's plating. To test this version, on February 14, Progress MS-21 was examined using a remote manipulator installed on the American segment of the ISS. During the inspection, photographs and video recordings of the outer surface of the ship were made, the materials were transferred to Earth for specialists for analysis. The results are not yet known.

Inspection of the ship "Progress MS-21" with the help of a manipulator. Photo: Roscosmos

Is there a threat to the ISS crew?

Both Roskosmos and NASA believe thatthe depressurization of the cargo ship did not affect the operation of the station in any way and did not pose a threat to the life of the crew. At the time of the incident, the passage hatch that connects the ship and the rest of the station was closed. The spacecraft had already been prepared for undocking, and all the necessary cargo was on board.

Additional cargo for crew work, includingincluding water and food, were successfully delivered by the next Progress MS-22 cargo ship. It left Baikonur on Thursday, February 9, and on Saturday, the same day the accident occurred, it successfully docked with the Zvezda module. Therefore, the team will not face a shortage of supplies.

However, due to the similarity of incidents inDecember last year and now Roskosmos has organized an inspection that should confirm the cause of the incident. Unlike the cargo vehicle Progress MS-21, which will burn up in the atmosphere, the manned Soyuz MS-22 was supposed to return the ISS crew to Earth. The December accident at this module changed the station's work plan.

How will astronauts and astronauts return to Earth?

There are currently 7 people on board the ISS:three core mission members and four crew members delivered by the Crew-5 mission of SpaceX's commercial program. Russian cosmonauts Sergei Prokopiev, Dmitry Petelin and NASA astronaut Francisco Rubio arrived at the station on Soyuz MS-22. And American astronauts Nicole Mann and Josh Kassada, Japanese astronaut Koichi Wakata and Russian cosmonaut Anna Kikina flew on an American ship.

The crew of the "Soyuz MS-22" before the start. Photo: Roscosmos

Crew-5 mission team before launch. Photo: SpaceX, NASA Kenedy

After investigating the December accident, NASA andRoskosmos agreed to temporarily revise the emergency crew rescue program, speed up work and send a new manned spacecraft Soyuz MS-23 to the ISS on February 20 without a crew. It is on it that three members of the main mission staff will have to return.

For emergencies prior to arrivalnew Soyuz, the plan assumes that Francisco Rubio will descend to Earth on the Crew-5 ship, along with four other flight participants who arrived at the station on this SpaceX ship.

The two remaining crew members (SergeyProkopiev and Dmitry Petelin) in this situation will return to Earth on the damaged Soyuz MS-22. The descent of two cosmonauts instead of three will be safer, according to Roskosmos: this will help reduce the temperature and humidity inside the ship. This scenario is considered solely as an emergency plan. After the arrival of the stable Soyuz MS-23, the emergency module will be sent to Earth with cargo and without passengers, and all three cosmonauts will descend on the new ship.

New circumstances postpone the launch of the SoyuzMS-23" for an indefinite period. So far, the head of Roskosmos, Yuri Borisov, has announced the postponement of the flight to March 2023 until the investigation into the circumstances of the accident is completed. This means that the astronauts who arrived on the Soyuz MS-22 will be delayed at the station, and the emergency evacuation plan remains in effect.

The head of Roskosmos, Yuri Borisov, comments on the incident and the postponement of the launch. Video: Roscosmos

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