The Shuttle system

All of the rocket launch vehicles used in the first two decades of space flight were expendable. This means that they could be used only once. This represented a very wasteful kind of technology. It made more sense, surely, to design a vehicle that could be used again and again. This thinking led to the birth of the US Space Shuttle, which made its maiden flight into orbit in 1981.

Three main elements make up the Space Shuttle transportation system. The main one is the winged orbiter, which carries the crew and the payload (cargo). It rides into space on top of a huge external tank, which carries fuel for its engines. Strapped to the sides of the tank are twin solid rocket boosters.

These elements are put together in the cavernous Vehicle Assembly Building at Complex 39 at the Kennedy Space Center in Florida, the main shuttle launch site. They are mounted vertically on a mobile launch platform, which is carried out to the launch pad by a huge crawler transporter.

The solid rocket boosters fire for two minutes before falling away. They parachute down to the ocean, where they are recovered. They are then towed back to the Space Center to be used again. The main engines meanwhile continue to thrust the Shuttle ever faster, ever higher, until, after eight minutes of flight, the external tank runs out of fuel. This is then discarded, and is not recovered. Two small engines then fire to accelerate the orbiter to orbital velocity (28,000 km/h) and place it in orbit.

Later, at the end of the Shuttle mission, these same engines fire again as retrorockets. They slow down the orbiter so that gravity can pull it back to Earth. It re-enters the atmosphere travelling at about 25 times the speed of sound, and air friction rapidly slows it down. It glides in to land, usually at Edwards Air Force Base in California, at a speed of about 350 km/h. A specially-converted Boeing 747 carrier jet is on hand to transport it back to the Kennedy launch site, to be prepared for its next mission.

On 12 April 1981 orbiter Columbia soars from the launch pad on the first Space Shuttle mission. On board are test pilots John Young and Robert Crippen. They touch down 54 hours later at the Edwards Air Force Base in California after a flawless flight.

Russia's shuttle
On 15 November 1988 a Russian space shuttle lifted off from Baikonur Cosmodrome in central Asia. The winged arbiter, named Buran, was making its maiden, unmanned flight. Buran looks much like the US Shuttle arbiter. It rides into space on the world's most powerful launch vehicle, Energia.

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