The International Space Station (ISS) relies on a complex system of thermal control to maintain its internal environment and protect its components from the extreme temperatures of space. A critical element of this system is the Ammonia Pump Module (APM), which circulates ammonia through the station's external Active Thermal Control System (ATCS). This system dissipates heat generated by the station's equipment and crew, ensuring optimal operational conditions. On August 18, 2026, astronauts Anil Menon and Sophie Adenot conducted a spacewalk to remove a failed Space-to-Ground antenna, a task that was completed successfully. However, due to time constraints, the replacement of the antenna was postponed to a future spacewalk, potentially scheduled for August 25, 2026. ([space.com](

Importance of the Ammonia Pump Module

The Ammonia Pump Module is integral to the ISS's thermal management. It pumps ammonia through the ATCS, which consists of external radiators that expel excess heat into space. This process maintains the station's internal temperature within a range suitable for both crew comfort and equipment functionality. The APM's reliability is paramount; a malfunction can lead to overheating, jeopardizing the station's systems and the safety of its inhabitants. ([nasa.gov](

Recent Maintenance Activities

In recent years, the ISS has undergone several maintenance activities to ensure the continued functionality of its thermal control system. Notably, in July 2023, astronauts Rick Mastracchio and Mike Hopkins conducted a spacewalk to install a spare Ammonia Pump Module. This task involved removing the spare module from the station's External Stowage Platform-3, transporting it to the S1 truss, and connecting it to Loop A of the ATCS. The successful installation of this module enhanced the station's thermal management capabilities. ([nasa.gov](

Upcoming Spacewalk for Antenna Replacement

The ISS crew is preparing for another spacewalk to replace the Space-to-Ground antenna removed on August 18, 2026. This antenna is crucial for maintaining high-speed data and communication transmissions between the ISS and mission controllers on Earth. The replacement is tentatively scheduled for August 25, 2026, and will involve astronauts Anil Menon and Sophie Adenot. The upcoming spacewalk will focus on installing the new antenna, ensuring the station's communication systems remain operational. ([space.com](

Conclusion

Maintaining the ISS's thermal control and communication systems is vital for the station's continued operation and the safety of its crew. The removal of the failed antenna and the planned replacement highlight the ongoing efforts to address technical challenges and ensure the station's readiness for future missions. As the ISS continues to serve as a hub for scientific research and international cooperation, such maintenance activities are essential to its sustained success. ([space.com](

Sources

  • NASA — Spacewalkers Complete Installation of Ammonia Pump Module —
  • NASA — NASA astronaut and 1st female French spacewalker remove failed ISS antenna but run out of time for replacement —