The Soyuz MS-22 spacecraft, currently docked at the ISS, had a spectacular coolant leak in mid-December, the images showing a jet of particles escaping into space from the rear of the Russian vehicle.

After examining the condition of the device, the Russian space agency (Roscosmos) announced on Wednesday that it considered it preferable to send another spacecraft, the Soyuz MS-23, to bring back the two Russian cosmonauts Sergei Prokopiev and Dmitri Peteline, as well as American astronaut Frank Rubio.

"It was decided to send the Soyuz MS-23 spacecraft on February 20, 2023 without passengers" but with equipment, Roscosmos said in a statement.

The take-off of this device was initially scheduled for March 16 and it was to carry three other passengers to the ISS.

The date of the return of the two Russians and the American, initially scheduled for March 28, has not been announced.

Their mission, however, has been "extended", Roscosmos has already indicated.

In addition, the damaged ship will return to Earth empty, according to Roscosmos, which nevertheless does not exclude the possibility of using this ship to transport passengers "in the event that a particularly critical situation arises on board the ISS".

There are currently seven people aboard the ISS.

Not counting the damaged Soyuz, only one rescue vehicle remains, capable of carrying only four people, in case the station needs to be evacuated.

Trace of a micro-impact

NASA is to hold a press conference later Wednesday to discuss the leak, detected on December 14 on the Soyuz as the two Russian cosmonauts were preparing to perform a spacewalk.

The ISS has been one of the few remaining fields of cooperation between Moscow and Washington since the start of the Russian offensive in Ukraine, launched on February 24, and the Western sanctions that followed.

Roscosmos chief Yuri Borissov paid tribute last month to the solidarity of Americans aboard the ISS, who "reached out a hand to help us", at a time when relations between the Kremlin and the White House are at the lowest.

The International Space Station was launched in 1998 at a time of US-Russian cooperation, following the space race the two countries had engaged in during the Cold War.

For Vitali Egorov, Russian specialist in space issues, the decisions announced Wednesday by Roscosmos are "optimal to ensure the safety of (the crew) and minimize the damage inflicted on the space program".

An initial assessment of the causes of the coolant leak raised the possibility of tears caused by small naturally occurring meteorites, man-made debris in orbit, or hardware failure.

On Wednesday, Roscomos claimed that the version of a "(micrometeorite) impact had been experimentally proven".

According to the Russian agency, this impact opened a hole "less than a millimeter in diameter" in a cooling pipe.

The Russian agency ruled out any mechanical failure, while this leak again raised questions about Russian equipment, generally considered reliable, but aging.

Several technical problems, in addition to corruption scandals, have tarnished the reputation of the Russian space sector in recent years, which rivaled that of the United States at the time of the space race.

The disappointment of the Soyuz MS-22 illustrates the risks that continue to exist, despite technological advances that make it possible to calculate and anticipate the trajectory of cosmic objects, unless they are too small.

Many experts are concerned about the proliferation of debris of human origin in space, for example from old artificial satellites, which they believe increases the risk of collision.

© 2023 AFP