A smoke alarm went off in the Russian segment of the International Space Station (ISS) early Thursday, but the situation has since apparently returned to normal, the Russian Space Agency (Roscosmos) said.
"At 04.55 Moscow time (0155GMT), a smoke detector was triggered in the service module (‘Zvezda’) of the Russian segment of the International Space Station during automatic battery charging, and an emergency alarm was activated," said a Roscosmos statement.
Cosmonauts working at the station turned on the air purification system, and after cleaning the atmosphere inside the module, went back to rest, Roscosmos said.
"According to the main operational control group of the Russian segment of the station, all systems are working normally, the air composition on board the station corresponds to the standard indicators," it said.
The Russian cosmonaut crew is preparing for a walk in outer space this evening, it said.
Roscosmos did not specify what sparked the alarm or whether or not the cause was eliminated.