Four astronauts have returned to Earth in the first-ever medical evacuation carried out by NASA. The SpaceX capsule splashed down in the Pacific Ocean near San Diego less than 11 hours after departing the International Space Station (ISS). NASA says the early return was ordered due to a 'serious' medical condition but has not identified which crew member was unwell. All of the astronauts were taken to a local hospital for overnight observation and the unwell crew member is now in good spirits an