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The external fuel tank is the largest
single component of the shuttle system, at
154 ft long and
27.6 ft in diameter. Empty, Columbia's tank weighed 66,000
lbs.
Filled with liquid hydrogen and liquid oxygen, it
weighed almost 1.7 million lbs.
After 8.5 minutes of
flight, the tank was jettisoned to burn up in the atmosphere.
The tank used on the Columbia mission
was a lightweight tank,
the type used for every shuttle
mission from 1983 to 1998;
the super-lightweight tank, which
weighs 7,500 lbs less,
has been used on many missions since
1998.
The lighter-weight tank is necessary for the higher
orbits and large
payloads of visits to the international space
station.
The tank used in the Columbia mission was, like all
shuttle external tanks,
built at Lockheed Martin's Michoud
Assembly Plant in New Orleans, Louisiana.
It was delivered to
Kennedy Space Center on December 20, 2000.
Spray-on foam insulation of the type
used on the external tank
is shown mounted on a test panel
attached to a NASA F-15.
The foam protects the fuel tank from
the thermal stresses of launch
and reduces the amount of ice
that forms on the tank's exterior,
which has a surface area of
about a third of an acre.
Liquid hydrogen compartment holds 390,139 gallons of H2,
weighing 230,000 lbs.
It is stored at minus 423 degrees Fahrenheit and is
the 2nd-coldest liquid known, after liquid helium.
The LOX tank sits atop the
liquid hydrogen tank and the "intertank" that mixes the fuels.
Although the liquid hydrogen tank is 2.5 times larger, the O2
tank weighs
three times as much because liquid oxygen is 16
times more dense.
The liquid oxygen is stored at minus 297
degrees Fahrenheit.
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