NASA's Giant Pool: The Neutral Buoyancy Laboratory

12 March 2013 / © ESA, NASA, /

The Neutral Buoyancy Laboratory (NBL) is an astronaut training facility maintained by and located at the Sonny Carter Training Facility near NASAís Johnson Space Center in Houston, Texas. The NBL consists of a large indoor pool of water, in which astronauts may perform simulated EVA tasks in preparation for upcoming missions. The NBL contains full-sized mock-ups of the International Space Station (ISS) modules and payloads, visiting vehicles such as the Japan Aerospace Exploration Agency(JAXA) HTV, the European Space Agency ATV, the SpaceX Dragon, and the Orbital Sciences Corporation Cygnus. Previously there was also a mockup of the Space Shuttle payload bay, but since Space Shuttle retirement it has been removed.

The NBL tank itself is 202 feet (62 m) in length, 102 feet (31 m) wide, and 40 feet 6 inches (12.34 m) deep, and contains 6.2 million gallons (23.5 million litres) of water. Divers breathe nitrox while working in the tank.


ROV does a practice run in the pool

an astronaut with the European Space Agency, performing an exercise in the pool with the body restraint tether

While the test coordinators run the simulated "mission," the test director and his team in the adjoining Test Director Control Room monitor the pool's systems and the health of the facility.

Close-up of a spacesuitís display and control module (DCM). Note the backward labeling, intended to be read with the aid of wrist-mounted mirrors

Attached to the front of the suit, whether itís in the pool or on-orbit, is the complicated metal harness called the mini-workstation. The mini-workstation is designed with slots, branches, and clip-holes into which a huge variety of different tools can be fitted. By far the neatest thing we were allowed to see was the body restraint tether (BRT), which is a large flexible tube-like tool used to fix an astronautís position relative to an object. One end of the BRT mounts solidly to the astronautís suit, and the other end is affixed to a station rail or other attachment point. The long middle section is made up of a number of socketed ball joints and is totally flexible until one end is twisted; the twisting applies tension to an internal wire, and the ball joints lock up against each other, freezing the BRT into a solid shape.

Much of this gear is absent on the suits used in the NBL. The PLSS backpack is replaced with a weighted plastic shell, since the NBL facility pipes in the astronautís water and air and power through a long set of cables. The suitís helmet, with its layered sets of polarized sun visors and opaque shades, is replaced with a much simpler shell helmet which still holds pressure but lacks any fancy shielding. And the DCM, with its unneeded electronics, is replaced with a featureless, weighted blanking plate.

researchers practising for examination of asteroids

The NBLís Suit and Tool Lab, where ďspacesuit tailorsĒ work to fit and customize suits for astronauts.

Refraction plays games with perspective when looking across the pool.

The upper half of Astronaut Luca Parmitanoís extravehicular mobility unit, mounted on the donning stand.

extravehicular mobility unit (EMU) suit being prepped for the dive.

ROV/camera control unit


The hyperbaric chamber, next to the poolís south wall. If thereís ever a pressure-related emergency, it can be treated right here.

Pipeline to the enormous sand filters which keep the NBL pool clean

The enormous sand filters which keep the NBL pool clean





Luca Parmitano and Chris Cassidy, following along with the dive briefing.


And at the laboratory there's even a special place where you can relax and have a drink