One Small Fin Kick for Man, One Giant Stride for Mankind

An astronaut training in the Neutral Buoyancy Lab at the Johnson Space Center.

NASA training programs help astronauts prepare for space missions by training them in the underwater environments that come closest to replicating the microgravity of space.

Ask a group of scuba divers what they love so much about diving and a number of them will undoubtedly say something along the lines of: ‘it feels like I’m floating in space.’ NASA, the U.S. space agency, picked up on this a long time ago when it implemented underwater exercises into its training programs. In fact, before being shot up 400 kilometers (250 miles) above the Earth to work on the International Space Station (ISS) NASA astronauts must log hundreds of hours training underwater, where they are assisted by professional scuba divers who help them prepare for space missions.

Landing on an asteroid and a mission to Mars are two of the future goals of the NASA space program. To train for these eventualities, astronauts must undergo intensive training to prepare them for what everyday life will be like in outer space. One of the main things they must train for is extravehicular activities (EVAs), an essential part of space travel that consists of any endeavor that takes an astronaut outside of a space shuttle or space station. Also known as spacewalking, astronauts conduct EVAs for a number of reasons, from installing new sections of the ISS to conducting repairs or maintenance on other equipment.

A panorama of the NASA Neutral Buoyancy Lab at the Johnson Space Center.

Training for EVAs underwater helps astronauts simulate the environmental changes they will experience in outer space, the most significant of which is the weightlessness of their bodies caused by microgravity. This is where underwater training comes in. The state of neutral buoyancy that scuba divers strive for—when an object has the same tendency to float as it does to sink—is the closest that astronauts can come to replicating the properties of microgravity that cause people and objects to float around space. Neutral buoyancy is not the same as microgravity, as astronauts still feel the weight of their suits and experience a significant amount of drag when training underwater, but it is as close as you can get on Earth. Depending on the situation they are training for—a Mars landing or an asteroid mission—astronauts-in-training are weighted to simulate the gravity of the target environment.

NASA astronauts conduct their training in two separate underwater environments: The Neutral Buoyancy Lab, an indoor pool located in the Sonny Carter Training Facility near the Johnson Space Center in Houston, Texas; and the Aquarius Reef Base off the coast of Key Largo, Florida. By doing so, astronauts work out the procedures and learn to use the equipment under extremely realistic circumstances.

Astronauts practice on a Hubble model underwater at the Neutral Buoyancy Lab under the watchful eye of NASA engineers and safety divers. Photo Credit: NASA.

Neutral Buoyancy Lab

The Neutral Buoyancy Lab (NBL) is an astronaut training facility operated by NASA in which astronauts perform simulated EVAs to prepare for upcoming space missions. The NBL contains the world’s largest indoor pool—measuring 62 meters (202 feet) in length, 31 meters (102 feet) in width, and 12 meters (40 feet) deep—with over 23.5 million litres (6.2 million gallons) of water inside. At the bottom of the pool, visible through the crystal clear and balmy 30˚C (86˚F) chlorine-treated water, is a full-scale mockup of the modules that make up the ISS, which allows astronauts to practice the tasks they will be expected to perform if and when they are sent to the ISS.

When training at the NBL, astronauts wear a modified, 135-kilogram (300-pound) EVA suit, or spacesuit, that is perfectly weighted to achieve neutral buoyancy. They are lowered by a crane into the depths that hold the replica of the ISS modules. While underwater, the astronauts prepare for everything they will do on the outside of the space station, installing and routing cables, replacing equipment, and repairing coolant modules or other equipment. Performing these tasks in an EVA suit requires learning a new set of unfamiliar motions and by practicing in the NBL astronauts develop the motion skills necessary to get them ready for the real thing.

An astronaut with the European Space Agency performing an exercise in the Neutral Buoyancy Lab with a body restraint tether. Photo Credit: NASA.

Ground Control to Diver Tom

Each astronaut training in the NBL is accompanied by four professionally-trained scuba divers who are there to assist the training mission and to ensure the safety of the astronaut during the operation. Two safety divers help move the astronaut from place to place as they conduct different tasks and are ready at a moment’s notice to shuttle the astronaut to the surface in the event of an emergency—such as a suit failure. A third diver aids the astronauts as they perform tasks, handing them the metal tools they need and making sure to add foam to their suit to compensate for the loss in buoyancy caused by the added weight of a heavy tool. The fourth diver operates an underwater camera that, along with other cameras placed throughout the training area, streams a live video feed of the exercise to the control room where test coordinators supervise on a series of monitors.

The safety divers breathe nitrox gas (46% oxygen, 56% nitrogen) and dive with two tanks to avoid decompression and ensure that they have enough breathing gas to stay below the surface throughout the entire session—which usually lasts six to ten hours, the actual length of an average spacewalk.

ISS modules visible at the bottom of the pool of the Neutral Buoyancy Lab.

Aquarius Reef Base

The Aquarius Reef Base is an underwater habitat located 5.6 kilometers (3.5 miles) off the coast of Florida, in the Florida Keys National Marine Sanctuary. Made up of a pressurized underwater structure that includes three connected compartments, the habitat is strong enough to maintain normal atmospheric pressure or ambient pressure. Here, groups of NASA astronauts, scientists and engineers live in the world’s only underwater research laboratory for up to three weeks at a time to conduct scientific research and train for future space exploration missions. Missions are conducted as part of the NASA Extreme Environment Mission Operations (NEEMO) program.

Astronauts training at the Aquarius Reef Base do not wear full spacesuits. Instead, they don full helmets and wetsuits and go outside to conduct simulated space walks, conducting tasks similar to what they would do in space.

Not only can astronauts-in-training replicate microgravity here by performing EVA simulations in a neutrally buoyant environment but they can also train for what it would be like to live for prolonged periods of time in a confined space with other astronauts. Indeed, teaching ‘expeditionary behavior’ is a key component of NASA training programs, which includes learning how to cohabitate peacefully with others. Following the principles of saturation diving allows the astronauts to live and work underwater for weeks at a time.

The aquanaut crew of the NEEMO 16 underwater exploration mission at the Aquarius Reef Base underwater habitat on Mission Day 1 (June 11, 2012). Photo Credit: NASA

High Fidelity Experience

The benefits of training for space exploration cannot be overstated. It is one of the only environments where astronauts can actually get a feel for what they can expect life to be like in the alien environment of outer space. NASA works very hard to achieve a ‘high fidelity experience’ that comes close to replicating the reality of spacewalking.

Each training mission is designed to mimic actual EVAs in terms of time, distance and task. Every detail is attended to, down to the 50-second communication delay experienced when transmitting from outer space to Mission Control on Earth.

“We have had astronauts say after a spacewalk that it felt just like the NBL, but without my divers,” Scott Wray, NASA extravehicular activity instructor and flight controller, told Sport Diver magazine in an article they wrote about the NBL.

It seems that the next best thing to traveling to a galaxy far away is diving down below.

  • Ryan Patrick Jones, Contributing Writer