KPDS 2003-2 Soru=99

The point is made in the passage that the reason for developing the new engine is to ----.

The space shuttle and its rockets are huge - some 4.5
million pounds at lift-off. About 85 per cent of that weight is
fuel. Since it is designed to work in a vacuum, the shuttle
must carry not only fuel but the oxygen to burn it. Because
this is an inefficient way to go, NASA engineers have
recently tested an engine that gets some of its oxygen on
the run. This should reduce takeoff weights by half. A
spacecraft equipped with this engine would take off like a
rocket. But within minutes, incoming air would begin to
supplement liquid oxygen. Once the spacecraft reaches a
speed of 1,500 miles per hour - twice the speed of sound -
the liquid oxygen would shut off completely and the engine
would burn fuel mixed with air. Consequently the craft
would accelerate to about ten times the speed of sound.
When the air got too thin for the engine to breathe, the
ship would shift back to rocket mode to punch its way into
space.