Astronauts aboard the International Space Station were directed to take shelter in their docked spacecraft on Friday and prepare for a possible evacuation after an air leak in the Russian segment of the orbital outpost showed signs of worsening. Nasa mission control instructed the four members of the Crew-12 mission aboard the International Space Station at 9.04 am (local time) on Monday to enter their docked Crew Dragon spacecraft and don their spacesuits as a precautionary measure. The crew, comprised of two American astronauts, one French astronaut, and one Russian cosmonaut, were asked to prepare in case a reported air leak required an emergency evacuation, a Nasa official said, as cited by Reuters.Nasa and Russia’s space agency, Roscosmos, the two principal operators of the International Space Station, have spent months debating the source of and possible remedies for persistent air leaks in Russia’s Zvezda service module, a critical component of the orbiting laboratory.While the leaks had remained relatively minor in recent months, the situation worsened on Monday, with the rate of air loss doubling from about one pound per day to two pounds per day, according to a senior Nasa official. The increase has renewed concerns over the integrity of the module and intensified efforts to identify a long-term solution.