NASA Astronauts train for spacewalks in America’s largest pool, the Neutral Buoyancy Lab. To simulate microgravity, they practice underwater using a full-scale replica of the space station. Astronaut Anne McClain describes a spacewalk as “hanging off a cliff and performing brain surgery at the same time.” Credit: Smithsonian | National Astronaut Day

Suit up with NASA astronaut Anil Menon. Johnson’s Neutral Buoyancy Laboratory in Houston provides astronauts an underwater atmosphere resembling zero gravity (weightlessness) to train for spacewalks. For years, NASA Astronauts have performed spacewalks outside the International Space Station for maintenance and upgrades while wearing the Extravehicular Mobility Unit (EMU) spacesuit. The spacesuit can weigh anywhere from about 250-300 pounds on the ground. Spacewalks are some of the most physical