Page 17 - Curriculum Visions Dynamic Book

Disposable and reusable parts
The boosters fall away when the Shuttle is still at a relatively low altitude, and so they do not heat up too much as they fall back through the atmosphere. They can be recovered
at sea for reuse. However, by the time the external tank
is empty, the Space Shuttle is close to the edge of the atmosphere, which is too far up for the tank to fall back unharmed to Earth. When it is released, it burns up during reentry through the atmosphere. This is the only disposable part of the entire Shuttle.
How the Shuttle was developed
Since the first rockets were launched, people have thought of them as reusable vehicles. Because space is a near vAcuum, there is no need to worry about an AerodynAmic shape
for a spacecraft moving outside the Earth’s atmosphere.
But within the Earth’s atmosphere any reusable craft will have to have many of the features of a conventional airplane, such as wings for lift and a tail for steering and stability.
The Space Shuttle idea was developed after Apollo 11 landed successfully on the Moon, combining the roles of both a space taxi and a spAce stAtion. But the budget needed for this project was more than the money devoted to the entire Apollo project—and Apollo got people not just into orbit but to the Moon! The budget allocated turned out to be a fifth of the Apollo budget—enough to develop a simple Space Shuttle, but not enough for the Shuttle to do anything.
It was realized that using the Shuttle was one good way of launching sAtellites and recovering them or repairing them if necessary (a usefulness that the Hubble SpAce Telescope, among others, was later to need).
To date, six orbiters have been built and two lost in accidents. The first, called Enterprise, was built in 1977. It was not a true spacecraft but was flown on the back of a specially adapted 747 airplane to test landing and other features of the orbiter. The first Shuttle that orbited the Earth was the Columbia in 1981.
AerodynAmic A shape offering as little resistance to the air as possible.
Hubble spAce telescope An orbiting telescope (and so a satellite) that was placed above the Earth’s atmosphere
so that it could take images that were
far clearer than anything that could be obtained from the surface of the Earth.
lift An upthrust on the wing of a plane that occurs when it moves rapidly through the air. It is the main way of suspending an airplane during flight. The engines simply provide the forward thrust.
sAtellite A man-made object that orbits the Earth.
spAce stAtion A large man-made satellite used as a base for operations in space.
vAcuum A space that is entirely empty.
 The first Shuttle craft, the Columbia, was launched on April 12, 1981.
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