A Russian rescue ship has successfully docked with the International Space Station (ISS), allowing three stranded Russian and American astronauts to return to Earth a few months after a coolant leak disabled their own spacecraft.

At 7:58 pm EST, the uncrewed Soyuz MS-23 spacecraft with 960 lb (435 kg) of supplies docked with the Poisk module some 260 miles (418 km) above northern Mongolia. The arrival of the new spacecraft brings the station crew a step closer to resolving a drama that began on December 14, 2022 when a leak was detected in the coolant system of the Soyuz MS-22 spacecraft that had transported NASA astronaut Frank Rubio and Roscosmos cosmonauts Sergey Prokopyev and Dmitri Petelin to the ISS in September.

Originally attributed to a micrometeorite strike, the coolant leak left the three men without a ride home, resulting in the delay of the next Soyuz crew flight and a general juggling of the docking schedule. An investigation by the ISS crew found an 0.8-mm hole into the external cooling radiator located on the service module.

The damaged MS-22 was deemed unsafe for a crewed return, so it will undock uncrewed and return to Earth in late March, while the MS-22 crew will return in September in MS-23. The Russian space agency Roscosmos wants the damaged spacecraft’s reentry capsule to come back intact rather than burn up in the atmosphere because it hopes to conduct an investigation. In August 2018, a Soyuz capsule visiting the station suffered an air leak and a robotic Progress cargo ship headed to the station had a similar coolant leak on February 11, 2023.

The leaks may have been due to some problem during liftoff of the two craft, rather than a meteor. However, the possibility of sabotage on the ground has been considered in the past, although no concrete evidence of this has been found.

Source: NASA