So on July 1 NASA rocketeers plan to choose one of three radically different designs for the X-33, a prototype for the next generation of reusable launch vehicles (RLV). NASA will give the winning company roughly $900 million for testing, and construction of the final spacecraft should begin by 2000. NASA hopes the new RLV can operate at a tenth of the shuttle’s launch costs and thus recapture a bigger share of the lucrative world market for commercial satellites; the United States used to launch them all, but now it handles only 30 percent.
The competing designs all look as if they’d be right at home in ““2001: A Space Odyssey.’’ While the shuttle piggybacks on a fuel tank and external boosters – all jettisoned after liftoff – the X-33s are self-contained, single-stage-to-orbit craft. The Rockwell version looks and flies very much like the present shuttle, which is no surprise since Rockwell built that, too. McDonnell Douglas’s entry is a nose cone on legs that takes off and lands vertically. The Lockheed Martin ship is the most untraditional, a fat flying wing called a ““lifting body’’ with an experimental engine. Each craft is designed to fly by remote control or autopilot. Materials like graphite composites and aluminum-lithium will permit lighter fuel tanks and more durable heat shielding – no more falling tiles. That, in turn, will allow for rapid turnarounds between flights.
NASA thinks that a working RLV is essential for an orbiting, permanent space station. That project continues on as an international effort slated for completion in 2002. According to Gene Austin, NASA’s X-33 program manager, by 2008 RLV missions ““will simply be cargo-and crew-delivery flights for space-station support and commercial launch capability.’’ That’s what they said about the shuttle, too.
NASA officials say that they expect the RLV to be a private-sector operation, with the government acting as a prime contractor. All three competitors have submitted business plans indicating who their customers will be and how much of the world launch market they expect to capture. NASA officials believe that a single-stage-to-orbit RLV with ’90s technology could launch as many as 30 times a year.
Not everyone thinks the X-33 program will fly. ““Going from the X-33 to an actual reusable launch vehicle is going to take, in the real world, $20 billion,’’ says John Pike, director of the Space Policy Project at the Federation of American Scientists. ““I don’t know where they’re going to get the money.’’ And 30 flights a year will require reliability like that of a jet plane, something no rocket ship has ever achieved. Pike thinks the future lies with projects like the Evolved Expendable Launch Vehicle, an air force program to develop new booster technology. In either case, the era of the space shuttle is slowly ending.
The flying-wing design and linear aerospike engine are intended to make both the X-33 and the RLV (artist’s rendering shown) efficient at any altitude.
A kind of space-shuttle sequel in body configuration, this design has stronger and lighter fuel tanks, heat shields and engines.
Its prototype is based on the five-year-old Clipper Graham experimental craft, which takes off and lands vertically.
