NASA has scheduled the X-33's first test flight for summer, agency officials announced this week. The plane is scheduled to complete 15 test flights by late 2000, according to Gene Austin, NASA's X-33 project manager.

During the first series of tests, the X-33 will fly high into the upper atmosphere at speeds up to MACH 8. Then, the stubby winged craft will be flown to the edge of space at up to MACH 11. It takes speeds of MACH 25 to achieve orbit. The maximum speed and altitude attempt will be made on the fifth flight, Austin said.

For the time being, the X-33 is in final assembly at the Lockheed Martin Skunk Works plant. Several of its systems, such as reusable liquid oxygen and hydrogen tanks, are being tested at NASA facilities around the country, as is the craft’s Aerospike rocket engines, which are to be test fired at the Stennis Space Center in Mississippi.

The vehicle’s thermal heat shield, which will use a metallic panel system more durable and lighter than the ceramic tiles used on the space shuttles, is also being flight qualified, Austin said. The rocketship’s thruster system has now been qualified for use in the missions.

The plane is scheduled to be finished and ready for rollout at Edwards Air Force Base in California early next year.

After construction and testing of the X-33 is complete, Lockheed company officials will decide whether to commit the company to building VentureStar, a full-sized spacecraft version of the X-33 that would serve as the basis for the first private spaceline.

Lockheed, which is building the X-33 under a 1996 NASA contract, must make the decision by the end of next year, based on technical data from the X-33 flight trials. Lockheed retains rights to the data under the terms of its deal with NASA.

Such a rocketship, the first ever-single stage to orbit launch vehicle, could replace the space shuttles early in the next decade and also eventually replace many of today’s throw-away rockets if it delivers on the promise of low cost operations and high flexibility.

But the daunting risk of a single stage craft, never before built, has cooled financial support for the plan outside of the industry. Wall Street investors have balked at funding the VentureStar, Lockheed officials were forced to admit to Congress earlier this year.

Jerry Rising, vice-president for the X-33/VentureStar project at Lockheed’s Skunk Works facility in Palmdale, California, has said he and others will not put the entire Lockheed Martin corporation at risk to build and operate VentureStar, no matter how promising the results of the X plane tests. Thus it may require additional government financing to develop the system beyond the end of the X-33’s year 2000 missions.

Nevertheless, dozens of states are already vying to host the VentureStar fleet if the project goes into development. And when the X-33 tests are over, the Air Force has expressed interest in possibly using the craft for military spaceplane development work.

Austin said Tuesday the missions will begin next summer with a brief 31 minute test launch lifting off from an entirely new launch pad at Edwards to a runway landing at Michael Army Airfield in Utah.

Should Lockheed proceed with construction of the VentureStar, it would be capable of lifting 56,000 pounds to low Earth orbit and 18,000 pound payloads to geostationary altitudes. By contrast, the space shuttle can lift approximately 56,000 pounds into low orbit, as can the Air Force Titan IV. The European Ariane 5 is in the same general payload lifting class, as is the Russian Proton booster.