On 21 July 2016, the crew for the 21st NASA Extreme Environment Mission Operations, or NEEMO, sortie descended to the underwater Aquarius base reef off the coast of Florida. During their stay they will enact a mission to Mars to test equipment for astronauts. The six ‘aquanauts’ will spend 16 days 20 m underwater in their habitat and perform ‘waterwalks’ – by adjusting their buoyancy, the aquanauts can simulate Mars gravity. Hervé Stevenin and Matthias Maurer from ESA's European Astronaut Centre are taking part in the mission.
Read more: Return to the underwater space station