. Just before 1:50 p.m. Eastern, the wedge-shaped craft was dropped at an altitude of 37,500 feet from a B-52 for a 13-minute flight after taking off from the agency's Dryden Flight Research Center at Edwards Air Force Base. The X-38 hit the clay surface of Rogers Dry Lake at a speed of less than 40 mph, slow enough for eventual human crews but fast enough for controlled flight.
"That thing was solid as a rock," Dryden spokesman Alan Brown said of the clean descent. "We were very, very pleased." During a test in November 2000, the X-38 twisted and wobbled unpredictably as it fell to Earth. Since then, engineers reprogrammed flight control software to take some aerodynamic asymmetries into account.
The X-38 is aimed at proving technologies needed to build a space-worthy Crew Return Vehicle (CRV) that could be docked to the International Space Station for the safe emergency return of a six-person crew.
As the unpiloted prototype descended on Tuesday, engineers tested aspects of the software used to control the craft, its landing parachute and a 7,500-square-foot fabric parafoil that unfurls for final descent.
"The vehicle had a twist on the shrouds of the parafoil during the test in November," Brown said. "This time the thing deployed perfectly straight and was in full control. The descent and aiming was very, very stable." The X-38 is designed for a targeted landing in an area the size of a football field.
The current test vehicle is made of fiberglass and scaled to 80 percent of the eventual CRV. Upcoming test vehicles will be full-size. One upcoming vehicle, number 133, will not be "space-rated," but is designed for atmospheric testing. Vehicle 201 will be space-rated and made of aluminum with thermal protection like that on the outside of the Space Shuttle. There is talk of cost-cutting by converting that vehicle for human flights eventually, rather than building another as previously planned.
The Tuesday flight also checked advances in deployment of the parachute, which slows the craft from 600 mph to about 60 mph.
"Each flight test of the X-38 incorporates technologies that have never before been used on a human spacecraft -- from satellite-based navigation to electromechanical actuators to the giant parafoil," said X-38 Program Manager John Muratore. "Every flight gives us invaluable insight into the performance of these technologies during an actual descent and brings us closer to proving them for use in space."
The flight was the second X-38 mission to include the large parafoil (previous tests relied in a 5,500-square-foot foil). The test also was the second flight of an X-38 shape that includes a semicircular cross section aft end, identical to the shape of an X-38 space vehicle planned for a test flight from a Space Shuttle in 2003 and now under construction.
The European-influenced semicircular aft end could allow the X-38 to be compatible with launch on a European Ariane V rocket as well as aboard the Space Shuttle.
The X-38 is to replace the three-person Russian Soyuz module, currently the only way to return to Earth from the International Space Station when there is no shuttle docked.
NASA had planned on a $1 billion craft that would be attached to the station. That project was axed in February when it was revealed the International Space Station would overrun projections by $4 billion. The
but prototype testing continues.The 29-foot-long, triangular-shaped pod, which uses its body like a wing, is needed if the station is to host crews of more than three and conduct significant science experiments.
As of April 2001, NASA had spent $66 million on the X-38.
NASA's Johnson Space Center in Houston leads the X-38 program and is building the space-rated test vehicles. The X-38 atmospheric test vehicles were built by Scaled Composites in California.
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