The alarm sounded at 1:55 a.m. GMT in the Zvezda service module of the Russian segment of the station – the latest in a string of safety concerns in that area.
“A smoke detector was triggered in the Zvezda service module of the Russian segment of the International Space Station during automatic battery charging, and an alarm went off,” Russian space agency Roscosmos said in a statement. “To eliminate possible smoke pollution by the crew, an aggregate filter for cleaning the atmosphere was turned on.”
French astronaut Thomas Pesquet said “the smell of burning plastic or electronic equipment” wafted to the U.S. segment of the station, though, according to CBS News.
The crew activated air filters and resumed “night rest” once the air quality had returned to normal levels. Roscosmos reported the air quality was safe, but it did not make clear whether or not there would have been a risk to the crew had the filters not been activated.
The agency confirmed that a planned six-hour spacewalk would proceed on Thursday to continue integrating the Russian-built Nauka science lab that docked with the ISS in July, Al Jazeera reported.
The Zvezda module has experienced a number of safety issues, with smoke reported in the module in 2014, and several air leaks, including one earlier this year and another in 2019.