- I’ve been studying astronaut psychology since Apollo − a long voyage to Mars in a confined space could raise stress levels and make the journey more challenging https://theconversation.com/ive-been-studying-astronaut-psychology-since-apollo-a-long-voyage-to-mars-in-a-confined-space-could-raise-stress-levels-and-make-the-journey-more-challenging-221960 45 comments space