On October 25th, 2023, the International Space Station (ISS) witnessed a dramatic encounter when two cosmonauts, Oleg Kononenko and Nikolai Chub, embarked on a spacewalk to address a coolant leak issue. The spacewalk was part of Expedition 70, and its primary mission was to isolate and document the radiator responsible for the coolant leak, first observed on October 9th. As they ventured outside the safety of the ISS, Kononenko and Chub were well aware of the potential hazards they might encounter. Their first task was to isolate the radiator and cut off its ammonia supply, used as a backup to regulate temperature within Russia’s Nauka multipurpose laboratory module. However, it wasn’t long before Kononenko noticed an alarming development – a growing “blob” or “droplet” of ammonia coolant. He reported seeing numerous small holes on the radiator’s surface, with edges so even that they appeared to have been drilled through.
The formation of the “blob” was attributed to the disturbance of residual ammonia during the valve closure procedure. To ensure the safety of the cosmonauts and the ISS, they had come prepared with tissues and cloths to decontaminate their spacesuits and tools, preventing any toxic material from entering the space station.
Data collected during the spacewalk will be instrumental for Russian engineers on the ground as they investigate the cause of the leak and plan for the radiator’s future use. In addition to their radiator inspection, Kononenko and Chub successfully installed a synthetic radar communications system, marking the first science payload on Nauka’s exterior. They also released a nanosatellite to test solar sail technology.
The spacewalk lasted for 7 hours and 41 minutes, concluding with the cosmonauts safely re-entering the ISS through the Poisk module airlock at 9:30 p.m. EDT. It was the 268th spacewalk in support of the space station’s assembly, maintenance, and upgrades, marking Nikolai Chub’s first spacewalk and Oleg Kononenko’s sixth. With this mission, Kononenko accumulated a total of 41 hours and 43 minutes working in Orlan spacesuits in the vacuum of space.
The event serves as a stark reminder of the risks and challenges that astronauts and cosmonauts face during their missions. The courage, dedication, and expertise of these spacefarers play a vital role in advancing our understanding of space and contributing to the ongoing success of the ISS.