An astronaut training in the NBL
Neutral Buoyancy Laboratory (NBL) is an astronaut training facility located at the
Training Facility and maintained by NASA's Johnson Space
Center in Houston,
Simulation control area
The NBL consists of a large indoor pool of
water, the largest in the world, in which astronauts may perform
preparation for upcoming missions. The NBL contains full-sized
mock-ups of the Space Shuttle
bay, flight payloads, and the International Space Station
The principle of neutral buoyancy
is used to simulate the weightless environment of space. Suited
astronauts are weighted in the water by support divers so that they
experience no buoyant
force and no rotational moment
about their center of mass
. The suits worn in the NBL are
down-rated from fully flight-rated EMU
suits like those in use on
the space shuttle and International Space Station.
The NBL tank itself is 202 ft. (61 m) in length, 102 ft.
(31 m) wide, and 40 ft. 6 in. (12 m) deep, and contains
6.2 million gallons (23.5 million litres) of water. Divers breathe
while working in the tank.
One downside of using neutral buoyancy to simulate microgravity
is the significant amount of
presented by water. Generally,
drag effects are minimized by doing tasks slowly in the water.
Another downside of neutral buoyancy simulation is that astronauts
are not weightless within
their suits, thus, precise suit
sizing is critical.
primary method used by NASA to simulate
microgravity is the so-called "Vomit Comet", an aircraft which performs a
number of parabolic climbs and descents to give its occupants the
sensation of zero gravity.
The vomit comet reduces the
problem of drag in weightless simulation. The main shortcoming of
this method is its time limitations - periods of weightlessness are
limited to around 25 seconds, interspersed with periods of
acceleration of around 2 g
aircraft pulls out of its dive and readies for the next run. This
is obviously not suitable for practicing EVAs, which usually last
Neutral Buoyancy Research Facility at the University of
Maryland's Space Systems Laboratory performs research into EVA techniques and robotic
interaction using neutral buoyancy as a basis for weightless