Smoke alarms went off in the Russian segment of the International Space Station in the early hours of Thursday.
The crew reported noticing smoke and smell of burnt plastic.
According to the Russian space agency Roscosmos, the incident took place in the Russian-built Zvezda module and occurred when the station’s batteries were being recharged.
The crew activated the air filters and returned to their “night rest” once air quality returned to normal, according to the agency.
The space station is currently operated by NASA astronauts Mark Vande Hei, Shane Kimbrough and Megan McArthur; Oleg Novitsky and Pyotr Dubrov, of Roscosmos of Russia; Japan Aerospace Exploration Agency astronaut Akihiko Hoshide and European Space Agency astronaut Thomas Pesquet.
Novitsky and Dubrov are scheduled to take a six-hour spacewalk on Thursday to continue integrating the Russian-built Nauka science lab that docked at the space station in July. Shortly after docking, the lab briefly made the advanced orbital site out of place by accidentally firing its engines, an incident that Russian space officials blamed for a software bug.