NASAexplores 9-12 Article: Two-Ton Hockey Pucks (PDF)

Two-Ton Hockey Pucks
Superman isn’t the only one who can move a
2-ton automobile with his pinkie finger.
Astronauts can do it, too. There aren’t any
cars in space, but the crew can move objects
of similar weight with just as much ease. In
microgravity, there isn’t any friction to
provide resistance; therefore, massive objects
can become air-borne with a simple nudge.
While it’s easy to move large pieces of
equipment, they may be difficult to maneuver
or stop. Nobody wants a 2-ton object drifting
out of control! To help astronauts maintain
control in space, astronauts practice what it’s
like to work in microgravity while still on
Earth.
That’s where it gets complicated. There isn’t a microgravity simulator that perfectly
replicates the environment of space. That’s why NASA has developed many different
simulators. Each one of these simulators re-creates a specific part of microgravity. The
KC-135 airplane allows astronauts to tumble through the air in a free fall. The Neutral
Buoyancy Laboratory permits astronauts to work in an underwater lab with similar
conditions to floating in space. Virtual reality simulators show astronauts the visual
aspects of space. Drop towers put objects and experiments in a near-microgravity setting
for short periods of time. But, where do astronauts practice moving those large,
cumbersome objects? They proceed to the Precision Air Bearing Facility (PABF) at
Johnson Space Center in Houston.
At this facility, astronauts use the airbearing
floor. Imagine a giant air
hockey table about 6 meters [m] (20
feet [ft]) wide and 9.1 m (30 ft) long,
says Tom Smith. He is the mock-up
manager for the PABF. Once on the
special floor, astronauts can manipulate
massive objects as easily as an air
hockey puck floats across a game table.
If you have ever played air hockey,
you’ve seen the hockey puck float on a
thin cushion of air blown from the
surface of the table. On the air-bearing
floor, it works conversely. The air is blown down through the hockey puck. This causes
the puck to hover just millimeters off the floor. For 2-ton hockey pucks to stay in a
position so close to the surface, that surface must be very smooth and level.
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The floor is constructed of steel plates lined up alongside one another. More steel plates
are combined to form pads. These pads are attached to the bottom of the objects that
astronauts practice moving. Compressed air is then released into a tube that runs along
the side and bottom of the plate. When running, the air-fed plates hover just above the
floor’s surface so that it only requires a nudge for large objects to effortlessly glide across
the surface.
What kind of maneuvers do astronauts practice on the
air-bearing floor? They mainly handle large orbital
replacement units—some as large as a car—and
learn how to carefully guide them in the right
direction. They also practice using tools the way
they’d be used in space. Without gravity to keep the
astronaut in place, a simple twist of a screwdriver can
send him or her spinning. Astronauts can compensate
for the torque created by drills, wrenches, and pliers
by anchoring themselves or bracing their bodies.
Engineers also use the air-bearing floor as they’re
developing products and parts that will travel into
space, Smith says. Something as simple as a door hinge can be tested to see how it will
work without the friction found on Earth. By moving the hinge on the giant precision airbearing
floor, it’s easy to see if modifications need to be made because of microgravity.
“Some people call this a zero-gravity room, but that’s not accurate,” says Smith.
“There’s plenty of gravity in here. This floor simulates the effects of reduced gravity on
one plane only, not throughout the entire room. It’s pretty amazing, though, to see how
easy it is to move something weighing 2 tons with just your pinkie.”
Related NASAexplores articles:
“Just In Case”—Emergency landing sites for Space Shuttle launches
http://www.nasaexplores.com/show2-articlea.php?id-02-010
“Drop Everything!”—Drop towers
http://www.nasaexplores.com/show2_articlea.php?id=02-006
“Microgravity: Always a Bad Hair Day”—Effects of microgravity
http://www.nasaexplores.com/show2_articlea.php?id=01-044
“The Weightless Wonder”—The KC-135 airplane
http://www.nasaexplores.com/show2_articlea.php?id=03-008
“Astronauts Take a Dive”—The neutral buoyancy laboratory
http://www.nasaexplores.com/show2_articlea.php?id=02-066
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