Early on the morning of June 21st, the first privately funded manned space flight took place in the skies over Mojave, California. With a record breaking altitude of over 100 kilometers (62 miles), Spaceship One, piloted by Mike Melvill, rocketed into the record books and might have changed the face of manned space travel. Sponsored by Microsoft billionaire Paul Allen, Burt Rutan's famous Scaled Composites aerospace research and development firm is the leading contender for the Ansari X-Prize, a $10-million purse for the first private venture to launch the same craft with three passengers on two suborbital flights within two weeks.
Several design concepts contribute to Spaceship One's success. First, the craft is carried to an altitude of 15,240 meters (50,000 feet) by another aircraft, the White Knight, a simple, glider-like craft powered by two conventional turbojet engines, saving tremendous amounts of fuel and weight. Second, both vehicles are built from state-of-the-art composite structures, using the techniques and aerodynamics that made Scaled Composites famous. Among other aircraft Scaled Composites built the Voyager aircraft that circumnavigated the earth unrefueled in 1986. Finally, Spaceship One's rocket motor is an hybrid design.
The hybrid rocket has a liquid oxidizer tank filled with nitrous oxide, but its fuel is a rubber-like solid composite. The composite fuel is similar to that employed in most military missiles and rockets and the Space Shuttle solid rocket boosters, but without an oxidizer included in the material. A valve injects liquid oxidizer into the hollow core of the solid fuel. Unlike a conventional solid-fuel rocket, a hybrid can be shut off, a big safety advantage, but the hybrid incorporates much of the simplicity and reliability of a solid-fuel motor.
It is expected that the White Knight and Spaceship One will carry passengers and complete the two flights in two weeks requirement within the next month or two. While the sub orbital flight isn't anything more than Alan Shepard did in 1961, two flights with the same spacecraft in such a short time is a trick neither NASA nor the Russians have figured out. Although Spaceship One isn't equipped with a heat shield or sufficient thrust for orbital flight, its innovations hold hope for future commercial space travel and reducing launch costs to support military satellite constellations. In addition to its participation in the X-Prize, Scaled Composites is teamed with Space Launch Corp. on the DARPA RASCAL (Responsive Access, Small Cargo, Affordable Launch) Program to launch 110 to 250 pound cargoes for $9,000 per pound within 24-hours of the arrival of a payload. While the cost is similar to the newest Atlas and Delta rockets (often quoted at $10,000), the turnaround time can't compare to the weeks or months of the conventional rockets. The RASCAL proposal includes runway takeoff and landing of a reusable, unmanned winged spacecraft.
Interestingly, the mothership-rocket plane concept has a history across the Muroc Dry Lake from the Mojave Airport. Between 1960 and 1968, the Air Force set numerous records for speed (4,520 mph) and altitude (354,200 feet) using the X-15 rocket plane launched from a B-52 mothership. More recently, Orbital Sciences privately developed the Pegasus rocket, a small satellite launch vehicle (up to 1,000 pounds to low earth orbit) that uses a commercial L-1011 airliner as a mothership.
With all the promise of the mothership approach, why has it been conspicuously absent from NASA's manned program? Part of this might be due to the workings of bureaucracy. After World War II, the Army was assigned Wernher von Braun and his team of German rocket scientists, who went to work on the first ballistic missiles at the Redstone Arsenal in Huntsville, Alabama. After the Air Force was split off and the formal divisions between it and the Army were worked out in the mid-50s, the Army had to limit the range of its missiles. As a result, von Braun and his friends wouldn't be allowed to build the big rockets they yearned to tackle. When NASA was formed in 1958, the rocket scientists in Huntsville quickly got themselves reassigned from the Army to the new space agency and got back into the big rocket business.
For a time the Air Force was set on developing an astronaut corps of its own, independent from NASA. Before the X-15, they trained in NF-104 fighters, F-104s with a solid rocket motor mounted below the tail. In 1963, budget cutters came to the conclusion the since the Russians went to space on a rocket, we should do the same thing. The Air Force program was axed and the mothership concept went largely unused for about forty years. Among other accomplishments, Spaceship One put Mojave back in the spaceflight business. -Andrew Wagner