X-43 mishap investigation update

The board studying the June 2 loss of the first X-43A mission
expects to find more than one factor responsible for the loss, said
Robert W. Hughes, the board chairman from NASA’s Marshall Space
Flight Center (MSFC), Ala. The team has ruled out most of 600
potential elements identified in a fault tree for the mishap. Hughes
stated previously that the likelihood of finding a single root cause
of the X-43A mishap was becoming less probable.

The X-43A is designed to be the first scramjet-powered
vehicle, capable of attaining speeds as high as Mach 10. The X-43A
mission, first in a series of three, was lost moments after the X-43A
and its launch vehicle were released from the wing of the NASA B-52
carrier aircraft. Following launch vehicle ignition, the combined
launch vehicle and X-43A experienced structural failure, deviated
from its flight path and was deliberately terminated.

Hughes repeated that the investigation team was working to
fully understand the causal relationship among many elements and
likened the board’s effort to putting together a jigsaw puzzle. “The
activities now being worked are to verify that the board has all the
pieces, the pieces are the right pieces and that the pieces fit
together in the right order to make a complete picture,” Hughes said.

The board continues to meet at the NASA Langley Research
Center (LaRC) in Hampton, Va. where they relocated from Orbital
Sciences Corporation in Chandler, Ariz. on September 10. Hughes said
the relocation of the investigation to LaRC allows the board to
better support analyses and testing being performed at LaRC, as well
as NASA’s Goddard Space Flight Center (GSFC), Md., and MSFC where the
bulk of the remaining effort is centered. He said work critical to
the investigation will continue at the NASA Dryden Flight Research
Center (DFRC), Calif., and at Orbital Sciences until the
investigation is complete.

“The bulk of the board effort remaining revolves around fully
understanding the critical elements of the control system and vehicle
aerodynamics,” Hughes said. Extensive wind tunnel testing with the
vehicle model and functional testing of the launch vehicle control
system has begun. Major analytical assessments have been completed
and others are in process to provide and assess the collected data.
The team has closed all but one branch of the more than 600-element
fault tree that was developed to assist in the investigation of the
mishap. The remaining branch deals with the launch vehicle control
system, aerodynamics and control elements, Hughes said.

The NASA Langley Research Center at Hampton, Va., leads the
X-43A program, with flight operations conducted by NASA Dryden.
Orbital Sciences Corporation of Chandler, Ariz., provides the launch
vehicle. Micro Craft, Inc., of Tullahoma, Tenn., built the
12-foot-long X-43A vehicle. The mishap investigation team includes
representatives from NASA centers including Dryden, Langley,
Marshall, Goddard, Kennedy (Florida), plus all of the contractor
elements.