Russian cosmonauts aboard the ISS were forced to seal a hatch and don protective equipment after the arrival of a cargo vessel brought with it a bizarre smell.

The hatch between the Russian side and U.S. side of the ISS is usually closed these days. For the past five years, there has been an ongoing air leak on the Russian side. NASA and its Russian counterpart, Roscosmos, continue to troubleshoot the leak, which poses no immediate risk to the ISS astronauts or station operations, NASA has stressed.

Russian cosmonauts discovered a foul smell and strange droplets floating around after opening the docked Progress 90 spacecraft.