One recent design idea for a reusable spacecraft was the X-33, or VentureStar

Based on the "lifting body," it would lift off in an upright position, orbit, then return to Earth and land belly-down on a runway.

Another design was the X-37. It would be launched into orbit from the space shuttle. It would work in orbit, then return to Earth by its own power.

The X–43 was a plane designed to launch spacecraft into orbit. Known as the “Hyper X, th is plane would fly at "hypersonic" speeds, many times the speed of sound. A “scram-jet engine would allow it to use oxygen from the air to burn fuel, instead of using costly rocket fuel. The Hyper-X could launch craft into space at a tenth the cost of the rocket-propelled space shuttle. In coming years, scientists will continue research to develop new experimental concepts.

4 Hyper-X

In this artist’s concept, the X-*3,or Hyper-X research plane, roars up towa’d the fringes of space. Such planes, resigned to fly many times tne speed of sound, may one day oe usee to launch vehicles into space orbit.

►x-33

The X-33, or VentureStar, flies in Earth orbit in this artist’s concept. It is one of many ideas for reusable vehicles to lower the cost of space travel. It would take off like a rocket, orbit, and land horizontally, like an arpiare.

Fun Fact: Split-Second Timing

The fastest "air-breathing," wingec aircra’t today, the SR-71 Blackbird, travels in soeeds measured in tens of miles-per-minute. Hypersonic p’a^es like the Hyper-X may travel in speeds of miles-per-second!

► Mother Ship

This art shows how the Hyper-X would be launched, riding on a rocket uncer the wing of a B-52. Dropped at 43,000 feet, the rocket would boost the Hyper-X to

100,0 feet, then fall off. The plane would fly on by its own power.

Testing, Testing

Scientist Vince Rausch holds a model Hyper-X mounted on a rocket in a wind tunnel. Wind-tunnel tests show such a plane could fly to Mach 10 to reach space. In an artist’s concept (right), a Pegasus rocket lifts a Hyper-X on its nose.

* X-37

In this imaginary scene, the X-37 is ready for launch from the payload bay of a space shuttle, Aoout half the length of the shuttle, this craft would orbit up to 21 days, performing experiments. lt would then return to Earth on its own.