Two cosmonauts embarked on a spacewalk outside the International Space Station (ISS) on Wednesday (Oct. 25) and had a close encounter with a coolant leak. The leak was initially observed flowing from an external radiator earlier this month. Oleg Kononenko got so close to the pooling ammonia, described as a “blob” or “droplet,” that one of his tethers became contaminated. As a result, the tether had to be bagged and left outside of the space station at the end of the spacewalk.
Kononenko and his fellow spacewalker, Nikolai Chub, began the extravehicular activity (EVA) at 1:49 p.m. EDT (1749 GMT) on Wednesday. One of their first tasks was to isolate and photograph the radiator, which was first observed leaking coolant on Oct. 9. The radiator serves as a backup to the main body radiator that regulates the temperature inside Russia’s Nauka multipurpose laboratory module. To cut off the external radiator from its ammonia supply, Kononenko and Chub configured a number of valves.
Once the isolation and documentation of the radiator were completed, Kononenko noticed the growing deposit of liquid coolant and reported seeing numerous small holes on the radiator’s panels. The holes had even edges, resembling drilled holes, and were spread in a chaotic manner. The “blob” is believed to have formed from the residual ammonia disrupted during the valve closure. The cosmonauts were prepared with tissues and cloths to wipe down their spacesuits and tools to avoid bringing any toxic material back inside the space station.
Russian engineers will analyze the data collected by the cosmonauts to determine the cause of the leak and develop measures to reuse the radiator in the future.
In addition to the radiator inspection, Kononenko and Chub also installed a synthetic radar communications system and released a nanosatellite to test solar sail technology. The radar, used to monitor Earth’s environment, was the first science payload mounted on Nauka’s exterior. However, the radar’s panels only partially deployed and the attempt to fully deploy them was unsuccessful.
The small cube-shaped nanosatellite, developed by a team at the Bauman Moscow State Technical University, was designed to test the deployment of an experimental solar sail. The nanosatellite was successfully released from its housing and slowly drifted away from the space station, but the solar wings did not extend as planned.
The 7-hour, 41-minute spacewalk concluded when the hatch to the Poisk module airlock closed at 9:30 p.m. EDT (0130 GMT on Oct. 26). This EVA was the 268th in support of space station assembly, maintenance, and upgrades. It marked Chub’s first spacewalk and Kononenko’s sixth, bringing his total spacewalk time to 41 hours and 43 minutes.
