An ISS backup circuit is leaking, according to the Russian space agency

The Russian space agency, Roscosmos, is searching for answers after one of its International Space Station modules leaked coolant, adding to its mechanical issues in low-Earth orbit over the past year.

On Monday, Roscosmos posted on Telegram that the coolant leak affected a radiator circuit on the Nauka module on the Russian-controlled segment of the ISS.

According to the Telegram, the leak occurred on an external, backup radiator circuit launched to the ISS in 2012, prior to the July 2021 addition of the Nauka module.

NASA reported Monday afternoon that Houston officials “observed flakes emanating from one of two radiators” on the Nauka module at 1 p.m. ET.

NASA reiterated that the primary radiator is working normally, the ISS crew is safe, and ground teams will continue to investigate.

NASA reviewed a Russian investigation that found a small object likely hit the spacecraft, causing the leak.

Late February saw a replacement Soyuz launch to the ISS. On September 27, that vehicle returned Rubio, Prokopyev, and Petelin safely.