Image taken from chase plane shows the rocket's out-of-control track. Photo: NASA-DFRC

The board investigating the June 2 X-43A mission loss is continuing to meet at the Orbital Sciences Corp. facility in Chandler, Ariz., where the Pegasus-derived booster rocket used with the X-43A was built.

The X-43A mission, first in a series of three, was lost moments after the X-43A and its booster rocket were released from the wing of the B-52 carrier aircraft. Following booster ignition, the combined booster and X-43A experienced a structural failure and deviated from its flight path. The mission was then deliberately terminated.

Robert W. Hughes, the board chairman from Marshall Space Flight Center, has said that the root cause of the mishap is still to be determined. The mishap investigation team includes representatives from five NASA centers including Dryden, Langley, Marshall, Goddard and Kennedy, as well as the primary X-43A mission contractors, Orbital Sciences Corp. and Microcraft.

Hughes stressed that the investigation team was working to fully understand the causal relationship and emphasized that the solution might involve several contributing causes rather than a single cause. He also pointed out that when a single cause for a mishap is not forthcoming, the difficulty of the investigation becomes significantly more complex because interrelationships of many events and data must be firmly understood to assure that all of the initiating causes are understood. Hughes also emphasized that the investigation team "is composed of the brightest and best experts in their fields" and that he has the highest confidence that a probable cause will be found.

To date, the team has established a fault tree of several hundred possible or contributing causes that are being systematically investigated. Approximately 70 percent of these faults have been eliminated from consideration. The majority of the remaining faults are in the booster vehicle control arena, Hughes explained.

The X-43A is designed to be the first scramjet-powered vehicle, capable of attaining speeds as high as Mach 10. NASA's Langley Research Center at Hampton, Va., leads the X-43A program, with flight operations conducted by NASA Dryden, Edwards, Calif. Micro Craft, Inc., of Tullahoma, Tenn., built the 12-foot-long X-43A vehicle.