Four astronauts had to cut their mission on board the International Space Station short after a “medical concern” forced NASA to return them to Earth weeks early. Now, Fincke has revealed a tantalizing clue about what went down during the first medical evacuation in the space station’s 25 years of continuous occupation. Among other things, ultrasound can be used to identify issues affecting muscles, joints, and tendons. To be clear, NASA hasn’t revealed any details about what caused the agency to orchestrate the first-ever medical evacuation. “So when we’re getting ready for Artemis, I am very optimistic.”More on the situation: Astronauts Helicoptered to Hospital After Mystery Evacuation From Space Station