Unpleasant surprise: Toxic odor in Russian ISS module

Progress 90, which had successfully docked with the Russian Poisk module a few days earlier, was supposed to provide supplies, including food, fuel, and research equipment.

However, when the crew opened the hatch, they noticed an unpleasant odour and small droplets of liquid, which led to the decision to temporarily isolate the Poisk module from the rest of the Russian segment of the station.

After opening the hatch of the Progress spacecraft, Roskosmos cosmonauts noticed an unexpected smell and small droplets, prompting the crew to close the Poisk hatch and isolate it from the rest of the Russian segment. The following day, flight controllers determined that the air quality inside the space station was at a normal level—NASA stated in an official communication.

The crew, wanting to ensure everyone's safety onboard, took precautions. Russian cosmonauts donned protective suits and oxygen masks, and activated the air purification system. At the same time, the American part of the ISS turned on its filtering devices to help purify the station's atmosphere.

According to the Russian Space Web, the smell was described as "toxic." Meanwhile, NASA astronaut Don Pettit described the smell as reminiscent of spray paint, although it is uncertain whether it was related to problems with the Russian cargo ship.

NASA experts suggest that the smell might have been caused by so-called outgassing, the process of gases being released from materials inside the spacecraft. This phenomenon is not uncommon in space, especially in enclosed environments where new items may emit volatile substances. After the segment of the station was ventilated, the smell quickly disappeared, and the crew was able to resume unloading.

Although the odour issue was quickly managed, it is not the only problem concerning the Russian segment of the ISS. NASA and Roskosmos have been monitoring an air leak in one of the Russian modules for some time. Currently, about 1.4 kilograms of oxygen is lost daily—significantly more than a few months ago, when the loss was 0.5 kilograms per day. This leak poses a serious threat to the station's resources and operations.

Progress 90, which delivered three tonnes of supplies, will remain docked to the station for several months before being filled with garbage and burned up in the Earth's atmosphere. Progress ships have played a crucial role in supplying the ISS for years, although recent incidents highlight the many challenges associated with space exploration.