Astronauts aboard the International Space Station were told to prepare for potential evacuation because of a worsening air leak. Nasa said the leak was coming from the Russian segment of the station, where cracks have previously been detected. Four of the seven crew " two US astronauts, a French astronaut and a Russian cosmonaut " received orders from Nasa mission control to enter their Crew Dragon spacecraft docked to the station wearing their spacesuits. Nasa said Roscosmos, the Russian space agency, will carry out repairs on Friday.