Alexander moving inside of the module mockup

ESA astronaut Alexander Gerst, from Germany, on a familiarisation course at ESA’s Neutral Buoyancy Facility at the Astronaut Centre, in Cologne, Germany, 8 June 2010.

This course teaches ESA astronauts basic spacewalk concepts and skills, such as tethering to the Station, the use of special tools, communicating with a crewmate and with the control room, and how to keep full situational awareness in a complex and challenging environment.

Training underwater is one way of simulating the weightlessness of space.