Russia originally had planned to send an unmanned Soyuz MS-23 spacecraft to the space station Feb. 14 to substitute for the docked Soyuz MS-22 spacecraft, which took the astronauts there and was to bring them back.

But while docked, the MS-22 capsule started to leak coolant last year after it was struck by meteoroid, and it was deemed unsafe to carry the space travelers home.

The rescue mission, however, was put on hold after another Russian spacecraft, the Progress MS-21 cargo ship, also docked at the space station, suffered a similar leak.

That raised questions whether the rescue craft also might start to leak during flight, possibly because of a design defect.

The Soyuz MS-22 spacecraft carried U.S. astronaut Frank Rubio, along with cosmonauts Dmitri Petelin and Sergey Prokopyev, to the space station Sept. 21.

Instead of bringing them home, it now is expected to return to Earth uncrewed after Soyuz MS-23 spacecraft has retrieved the crew.

Yuri Borisov, the head of Roscosmos, announced the delay in the rescue mission.

"Roscosmos continues to investigate the cause of the depressurization of the thermal control system of the Progress MS-21 cargo ship, which occurred on Feb. 11 at the International Space Station," the space agency said in a post on Telegram.

Russian officials said that they collaborated with NASA to inspect a possible damage site on the outer surface of the ship.

"Now, the American side is bringing the manipulator to the Progress MS-21, after which a video camera will be used to film and film the ship's instrument-aggregate compartment," Roscosmos said after the leak on the supply ship was detected.

"The received materials will be transferred to Russian specialists on Earth for further analysis."

Later Tuesday, Roscosmos said that the inspection of the Progress MS-21 cargo spacecraft was completed, and that officials will investigate the reason for the depressurization of the ship's thermal control system.

Sophie Goguichvili, the program associate for the science and technology innovation program with the Wilson Center think tank in Washington, D.C., told UPI that meteoroids will continue to be an issue for Roscosmos and other spaceflight operators.

"This is going to continue being a problem, and will be further exacerbated due to additional threats brought on by man-made orbital debris, often generated by the use of anti-satellite weapons," Goguichvili said.

She noted that the U.S. Space Command is tracking more than 47,000 objects in space, which is fewer than 0.01% of objects that are orbiting Earth.

"These objects can travel at incredibly high speeds, fast enough for a relatively small piece of debris -- even a speck of paint -- to damage a satellite or a spacecraft," she said.

"And with each new collision, tens of thousands of pieces of debris are created and exponentially increase the threat of future collisions [a phenomenon known as the Kessler Syndrome], which further put space systems such as the ISS -- and the people inside of them -- in grave danger," Goguichvili said.

"This is not the first time Russian spacecraft have suffered leaks," she added.

She said that a "slight drop" in cabin pressure at the space station in 2018 was traced back to a small hole in the habitation compartment of the Soyuz MS-09 spacecraft.

"Upon investigating it, Russia blamed NASA astronauts and even alleged that a U.S. crew member 'drilled the hole' deliberately. So even without the war in Ukraine, diplomatic tensions were high," Goguichvili said.

Because of that incident, Goguichvili called it "understandable" that NASA and Roscosmos would want to investigate further after a second consecutive coolant leak in a matter of months to ensure that Soyuz MS-23 will be capable of returning the three astronauts back home.

"The probability of two leaks occurring only two months apart when such events haven't occurred in the 25 years the ISS has been operating seems frankly incredible, and hence makes it even more impossible to ignore," Goguichvili said.

Despite any tensions on Earth between the two governments, Goguichvili said that U.S.-Russian cooperation aboard the ISS "is quite free of tension," which she attributed largely to the need of astronauts and cosmonauts to operate the research outpost.

"NASA has been working with Roscosmos throughout the investigation and will continue to work with its Commercial Crew Program and Canadian, Japanese and European partners to refine upcoming flight dates over the next several weeks," the space agency said in a statement in January.

"NASA also continues its discussions with SpaceX regarding the possibility of using the Crew-5 spacecraft to return additional crew in the event of a station emergency prior to the arrival of Soyuz MS-23."

NASA's SpaceX Crew-6 mission is to carry another crew of astronauts to the space station aboard a Dragon spacecraft on a Falcon 9 rocket Saturday, officials said.

NASA astronauts Stephen Bowen and Warren Hoburg will be a part of that crew, as well as astronaut Sultan AlNeyadi from the United Arab Emirates and Roscosmos cosmonaut Andrey Fedyaev.

During a media briefing earlier in January, NASA ISS Program Manager Joel Montalbano noted that a SpaceX Dragon capsule could not be sent to rescue the astronauts from the Soyuz mission because the Dragon capsule requires a different space suit from Russia's Soyuz spacecraft.

Officials added during that news briefing that the Soyuz MS-22 aircraft is not repairable from space if parts were sent to the space station because damage occurred on the end of the spacecraft farthest from the docking port, where there are no handrails or support structures for astronauts.

Though concerns exist for the safety of the astronauts amid their prolonged mission at the space station, Montalbano said in January that "there's no immediate need for the crew to come home today."

But the current situation does break a safety rule, Goguichvili said.

"For as long as the ISS has been operational, there has been an ironclad rule that there can only be as many people on board as you have lifeboats to get them off," she said. "And right now, that is not the case."

Related Links
Space Tourism, Space Transport and Space Exploration News