ESA astronaut Alexander Gerst tests a spacesuit at NASA’s Johnson Space Center in Houston, USA. This is the first time Alex donned a replica of the Extravehicular Mobility Unit as used on the International Space Station.

Alex spent many hours training to use it in swimming pools in similar suits, adjusting the fit to his body. The ‘fit check’ ensures the adjustments are correct on the real thing. Part of the check involves creating a vacuum to make sure the suit can be worn comfortably in an environment similar to space.

The lights on the helmet illuminate the working area when the International Space Station is over Earth’s night side. It only takes 90 minutes for the orbital outpost to circle our planet so half of the time is spent in darkness. The helmet lights allow astronauts to continue working outside.

Alexander Gerst is flight engineer for Expedition 40/41, which will be launched to the Station in May 2014 on a long-duration mission to run science experiments and maintain humankind’s space base.