An immense water tank to train astronauts in weightlessness. The tank used by NASA contains 23.5 million L and is 12.2 m deep. It is part of the Sonny Carter Training Facility at the Johnson Space Center, Texas. Trainee astronauts practise extravehicular activities (EVAs) around mock-ups of a shuttle payload bay and airlock. Astronauts wearing EVA spacesuits practised assembly of the International Space Station using mock-ups sunk in the tank. The facility is also used to test spacecraft designs and EVA equipment. Russian cosmonauts train in a neutral buoyancy tank at Star City in Russia.