A submerged space station
The European Astronaut Centre (EAC), established in 1990, is the base for the European Space Agency's (ESA) astronaut corps. One of its most significant training areas is the Neutral Buoyancy Facility (NBF). This is a swimming pool; it's a 10-meter-deep tank containing 3.7 million liters of water, heated to a constant 28°C for comfort during long training sessions. The pool's total dimensions are 22 meters long by 17 meters wide. Inside this vast tank rests a 1:1 scale mockup of the International Space Station's (ISS) Columbus module, a European-built laboratory.
By carefully weighting astronauts in their training suits, instructors can make them neutrally buoyant. This state closely mimics the weightlessness experienced during an Extra-Vehicular Activity (EVA), commonly known as a spacewalk. It allows astronauts to practice maneuvering around the exterior of the station, handling tools, and performing complex repair or installation tasks. Every ESA astronaut begins their path to space here, with a 12-month basic training program that includes SCUBA diving in the NBF as a first step towards full EVA preparation. This underwater training is a part of preparing for the physical and spatial challenges of working in orbit.