Spacecraft
Fire Safety
Facilities
Scientists
- also called Principal Investigators or PIs - in
the Spaccraft Fire Safety
program can conduct experiments
in facilities
that provide short and long periods
of microgravity. These facilities include drop towers
of various heights, reduced gravity aircraft,
sounding rockets, the space shuttles, and
the International Space Station.
Drop Towers
 |
| A view down
the 2.2-Second Drop Tower at NASA Glenn as an
experiment is
being retrieved after
a drop. |
A drop tower is a
long vertical shaft used for dropping experiment
packages, enabling them
to achieve microgravity through freefall. Various
methods are used to minimize or compensate for air
drag on the experiment packages as they fall. Glenn
Research Center in Cleveland, Ohio, has two drop
facilities (one 24 meters tall and one 132 meters
deep) that can accommodate experiments which need
only a limited amount of time (2.2 or 5.2 seconds)
in microgravity or which are test runs of experiments
that will be performed for longer periods in
an aircraft, rocket, or spacecraft. For more information,
visit the 2.2-Second
Drop Tower Web site.
Reduced Gravity Aircraft
 |
| A diagram of a typical
zero-g maneuver in a C-9B aircraft. By adjusting
the maneuver, the aircraft can provide zero g,
one-sixth g (as on the Moon), or one-third g
(as on Mars). |
NASA uses a C-9B -- the military vesion
of the commericial DC-9 -- to simulate conditions
of weightlessness. In a typical flight,
it performs
a series of large parabolic arcs by climbing to 32,000
feet and then diving 24,000 feet, its fuselage pitched
down at 40 degrees. At the top of the parabola, passengers
lose all sense of gravity and become weightless for
a period of roughly 25 seconds. When the airplane
comes out of the dive and begins its next ascent,
the plane pitches upward at about 50 degrees and
passengers on the craft are subjected to forces up
to 1.8 times that of gravity. This climbing and diving
is repeated thirty times in what might be described
as the ultimate roller coaster ride.
Passengers
often become nauseated, so much so that the plane
has been nicknamed
the "Vomit Comet." But that didn't stop director
Ron Howard and his crew, who used a KC-135A (the
predecessor to the C-9B) to film the weightlessness
scenes for the movie Apollo
13.
Sounding Rockets
Sounding rockets produce higher-quality
microgravity conditions for longer periods of time
than airplanes. An experiment is placed in a rocket
and launched along a parabolic trajectory that's
similiar to the C-9B, but much higher and for longer
periods. Microgravity conditions are achieved during
the several minutes when the experiment is in freefall
prior to reentering Earth's atmosphere.
 |
| The launch of a Space
Shuttle. |
Space Shuttles
A space shuttle is a reusable launch
vehicle that can maintain a consistent orbit and
provide up to 17 days of high-quality microgravity
conditions. The shuttle can accommodate a wide range
of experiment apparatus and a laboratory environment
in which scientists can conduct long-term investigations.
NASA has three shuttles: Atlantis, Discovery and
Endeavour.
The International Space Station
(ISS)
 |
| A photo of
the International Space Station taken in October
2002. |
The ISS is a permanent
facility that maintains a low-Earth orbit. The
facility enables scientists to conduct their experiments
in microgravity over a period of
several months without having to return the entire
laboratory to Earth each time an experiment is completed.
Facilities aboard the ISS that can be used for Spacecraft
Fire Safety experiments include the Express Rack,
the Microgravity Science Glovebox, and the Combustion
Integrated Rack.
and Accessibility Certification