A Russian spacecraft, Progress 90, leaked a strange odor and droplets upon docking with the International Space Station (ISS) on Saturday, alarming astronauts.

The odor was described as “toxic,” prompting the crew to seal off the hatch and activate air scrubbers while monitoring air quality.

After confirming the air was safe, the hatch was reopened, and the spacecraft, carrying supplies for the ISS, remained docked for six months.

The spacecraft will later be used to dispose of waste before burning up upon reentry into Earth’s atmosphere, the New York Post has reported.

The ISS, a collaboration of 15 countries, will continue operations through 2030.

Written by B.C. Begley