The Soyuz MS-22 spacecraft, launched on September 21, 2022, was part of a mission to transport crew members to the International Space Station (ISS). However, in December 2022, a significant issue arose when a coolant leak was detected in the spacecraft's external cooling loop. This leak prompted immediate investigations and led to adjustments in the mission's operations. This article provides an overview of the incident, the subsequent actions taken, and the current status of the Soyuz MS-22 spacecraft as of August 2026.

Detection of the Coolant Leak

On December 14, 2022, during routine preparations for a spacewalk, Russian cosmonauts Sergey Prokopyev and Dmitri Petelin observed a substantial leak from the Soyuz MS-22 spacecraft docked to the ISS's Rassvet module. The leak was traced to the spacecraft's external cooling loop, which is crucial for regulating the temperature of onboard systems. The detection of this leak led to the immediate postponement of the planned spacewalk to assess the situation further. NASA and Roscosmos, the Russian space agency, initiated a joint investigation to determine the cause and potential impact of the leak. ([nasa.gov](

Investigation and Findings

Following the detection of the leak, Roscosmos engineers conducted a series of tests to evaluate the spacecraft's systems. These tests confirmed that the leak originated from the external cooling loop. Additionally, an inspection using the ISS's Canadarm2 robotic arm revealed a small hole, approximately 0.8 millimeters in diameter, on the spacecraft's instrumentation compartment. This hole was identified as the source of the leak. Roscosmos officials characterized the situation as "not very pleasant" but emphasized that the temperature inside the spacecraft remained within acceptable limits, stabilizing at around 30 degrees Celsius. ([tass.com](

Impact on Mission Operations

The discovery of the coolant leak had significant implications for the Soyuz MS-22 mission. Initially, the spacecraft was intended to return its crew to Earth in March 2023. However, due to the leak and the associated risks, Roscosmos determined that Soyuz MS-22 was not viable for a normal crew return. Consequently, the Soyuz MS-23 spacecraft was launched uncrewed on February 20, 2023, to replace Soyuz MS-22. This replacement ensured the safe return of the crew members—NASA astronaut Frank Rubio and cosmonauts Sergey Prokopyev and Dmitri Petelin—who had been aboard the ISS for several months. ([nasa.gov](

Return of Soyuz MS-22 to Earth

With the crew transferred to Soyuz MS-23, Roscosmos proceeded with plans to return Soyuz MS-22 to Earth. On March 28, 2023, the spacecraft successfully undocked from the ISS and re-entered Earth's atmosphere. The descent was conducted without crew onboard, as the spacecraft's internal temperature had risen to approximately 50 degrees Celsius due to the coolant leak. This elevated temperature posed potential risks to both the crew and the spacecraft's equipment. Roscosmos officials stated that, had the spacecraft been occupied, the internal temperature could have reached around 50 degrees Celsius, which could have been detrimental to the crew's health and the spacecraft's systems. ([news.mynavi.jp](

Current Status and Future Considerations

As of August 2026, the Soyuz MS-22 spacecraft remains a subject of interest for space agencies and the aerospace community. The incident underscored the importance of rigorous quality control and inspection processes in spacecraft manufacturing and maintenance. Roscosmos and other space agencies have since implemented enhanced protocols to prevent similar issues in future missions. The Soyuz MS-22 leak also highlighted the critical role of international collaboration in addressing challenges related to human spaceflight. NASA and Roscosmos's joint efforts in investigating and mitigating the leak exemplify the cooperative spirit essential for the success of long-duration missions aboard the ISS. ([nasa.gov](

In conclusion, the Soyuz MS-22 coolant leak incident was a significant event that led to comprehensive investigations and operational adjustments. The successful return of the spacecraft without crew ensured the safety of the ISS crew and preserved the integrity of the mission. The lessons learned from this incident continue to inform and improve the safety protocols and operational procedures for future space missions.

Sources

  • NASA — NASA Provides Update on International Space Station Operations —
  • Roscosmos — Evaluation reveals 0.8mm hole in Soyuz MS-22 spacecraft —
  • NASA — International Space Station Operations, Soyuz Status Update —
  • Roscosmos — Soyuz MS-22 spacecraft suffers 'fairly substantial' leak at space station —
  • Roscosmos — 冷却剤漏れの「ソユーズMS-22」宇宙船、無人で地球に帰還 —