The last decade of the second millennium saw the emergence of the idea of sending payloads into space with reusable launch vehicles (RLVs). It appeared to make economic sense to reuse a launch vehicle that cost as much as a small airliner, rather than throw that vehicle away after one use. Two prototypes—the McDonnell Douglas Delta Clipper and Rotary Rocket's Roton—were built and flown at low altitude. A number of small companies emerged, each seeking to build an RLV. Although this idea has gained broad acceptance, no RLV has flown in space in recent years and none is likely to for many years.

An Old Idea and a Proven Technology

It is a misconception that a number of technological breakthroughs are required before RLVs will be feasible. An American experimental RLV, the X-15, made its maiden flight on June 8, 1959. The X-15 was...