It was all systems go at Lockheed Martin this July when NASA selected the aerospace enterprise to design, build, and test the first major new space vehicle for the U.S. in a quarter century. Lockheed Martin's concept -- the single-stage-to-orbit X-33 VentureStar reusable launch vehicle -- prototypes commercial space fleets for the new millennium and truly pioneers the next frontier. The X-33 changes space travel as we now know it -- rocket, boosters, and fuel tanks that separate from a shuttle -- with a vehicle that takes off vertically, climbs into orbit with a single stage, and lands on a conventional runway. Although Lockheed was working on single-stage concepts in the late 1980s, the results were marginal, says Bob Baumgartner, X-33 deputy program manager, Lockheed Martin Skunk Works. "In 1992 we started getting back to being involved in single-stage orbit because we felt that single-stage orbit, a low-cost reusable launch vehicle [RLV], was a true national need." Lockheed's reentry into RLVs culminated in the NASA announcement this summer. Since then, Lockheed has completed a systems requirement review and a preliminary design review and is preparing for a critical design review next summer. At that time, drawings will be completed and detailed fabrication will begin. The X-33 demonstrator model is scheduled to fly by Mar. 1, 1999. The four-year launch-vehicle program begins December 1999, meaning full-scale test flights should begin in December 2003 with operational service in late 2004. "Several new technologies were needed to make the single-stage orbit work," says Baumgartner:
- Propulsion system: Propulsion is achieved with linear aerospike rocket engines, fueled by liquid hydrogen/liquid oxygen (LH2/LO2). "It's a new high-technology vehicle in that we're just using safe nontoxic LH2/LO2 to power all the systems on the vehicle": main propulsion system, reaction-control system, and turboalternator, a device that creates electricity for the all-electric power system (no hydraulics). There will be two LH2/LO2 engines on the demonstrator and seven on the full-scale vehicle.
- All-composite structure: All large vehicles to date have been made of metal, and this change will result in substantial weight savings. An emphasis on weight reduction is a major means to reducing operational costs -- reportedly by 90%.
- Metallic thermal protection system: Robust 18-in.-by-18-in. metallic panels cover the craft, instead of the much smaller ceramic tiles found on shuttles that frequently need to be replaced.
- Lifting body: Lifting-body aerodynamics create a craft that surrounds the tanks and generates enough lift to land, which eliminates the need for wings and fuel to land, and also reduces weight.