NASA completed its first medical evacuation early Thursday, when an ailing astronaut and three others splashed down in the Pacific Ocean, more than a month ahead of schedule.

A SpaceX capsule has splashed down back to Earth carrying four astronauts from the International Space Station, after a medical issue prompted them to evacuate and cut their mission a month short.

Roughly a day later, NASA held a news conference, officially announcing the first medical evacuation in the space station’s 25-year history.

Depending on the timing, NASA could launch a fresh crew to the space station while four other astronauts are flying around the moon.