|
Idiots Space.com 'reports' below. Still no explanation on why Israel gets more |
|
X-43A
Failure Investigation Still Looking for Cause
HAMPTON, Va. --
Investigators remain hard at work trying to decipher why the X-43A research craft and its launch booster careened out of control June 2. The X-43A was the flagship vehicle in NASA's multi-pronged Hyper-X effort to explore scramjet-powered flight. After months of intensive detective work, a special board of experts studying the X-43A failure cannot pinpoint a specific reason that caused the research craft and Pegasus derived booster combination to spiral wildly through the air. The likelihood of spotting a single root cause of what NASA terms a "mishap" has become doubtful. Last
June, a few seconds after the unpiloted X-43A was released
from the space agency's B-52 carrier plane, and shortly
following ignition of the modified Pegasus XL booster, the
vehicle combination began corkscrewing away from an
intended flight path. To those present and in viewing
video of the doomed flight, pieces of the booster were
clearly seen breaking free from the still-coupled vehicles. In
deviating from a prescribed trajectory, the flight
hardware was then ordered to self-destruct over a Pacific
Ocean test zone. Software or hardware changes? "We're
finding that there are small things all along the line
that contributed to what happened. There's not a single,
total event," said Robert Hughes, who chairs the
X-43A Mishap Investigation Board now looking into the
failed flight. He is from NASA's Marshall Space Flight
Center in Huntsville, Alabama. Hughes
told SPACE.com that he hopes the X-43A mishap
findings, including "where-to-go-from-here"
recommendations, can be wrapped up in late December or
early January. A formal report might be released in late
January, he said. "When you go into a failure investigation, you are hoping that you'll find something gross -- like somebody taking a picture with a lens cap still on the camera. And that is something that we didn't see," Hughes said. Rausch
said that he hoped a return to flight would be
possible making software changes as opposed to a
hardware fix. A different launch altitude, release
speed, and trajectory is likely to be part of the
second test hop of an X-43A. Doing so "would
buy back less risk in the boost" phase of the
flight, he told SPACE.com. Intricate
investigation
Hughes
has been involved in more than 20 different failure
investigations, including the Challenger shuttle
tragedy in January 1986. The X-43A mishap team has
been busy at work for over 25 weeks -- a task that
the board leader first envisioned might take on the
order of 120 days. The mishap investigation team
includes representatives from a number of NASA
centers and industry contractors. "Putting
the pieces together on this -- this is probably one
of the more intricate and a little more difficult
investigations that I've been on," Hughes said.
"It has been a long haul." Good
data was received from both the well-instrumented
booster and X-43A research vehicle prior to
destruction and ocean impact. Many
witnesses of the June X-43A flight point to the
Pegasus XL-derived booster as the clear culprit of
the failure. Significant
changes were made to the Pegasus to meet the unique
requirements of the Hyper-X program by the booster's
builder -- Orbital Sciences Corporation (OSC) of
Chandler, Arizona. For
example, the rocket's second and third stages were
eliminated, as was the fairing, which is normally
used to protect satellite payloads. The X-43A
research vehicle and its adapter rode atop the front
end of a specially configured first stage solid
rocket motor. Additionally,
a newly developed thermal protection system
protected the Pegasus composite structures against
severe heating loads associated with low-altitude
hypersonic operations. Other modifications were made
in upgrading first stage guidance hardware and
repackaging avionics gear to assure stability of the
rocket as it sped toward hypersonic flight
conditions. Open
and shut case
But
given that pieces broke off the Pegasus, why not an
open and shut case? "We
would have loved to say that," Hughes said.
What caused the pieces to fall off in the first
place has become tough to pin down, he added. "The
launch vehicle was not considered to be the higher
risk element. The higher risk element, of course,
was the Hyper-X vehicle. So there was not as much
depth put on the launch vehicle. But there wasn't
inattention. And that's what we're finding. It is
not inattention. It's things that you have to really
weed way down to find," Hughes said. Rausch
said that there was difference enough between the
standard Pegasus and the rocket attached to the
X-43A that OSC "treated [their booster] as a
first flight article." "There
are significant differences, and there are
significant similarities as well. To the casual
observer it looks like an identical vehicle. When
you get to the details, it's not identical,"
Rausch said. Common
threads
Testing
at Langley has been underway, Rausch said, to go
back and validate the aerodynamics of the
Pegasus/X-43A "stack" - especially during
the transonic portion of the flight. Transonic
refers to the aerodynamic flow or flight conditions
at speeds near the speed of sound. Drawing
upon on his past investigations, Hughes said there
are common threads in why things fail.
"Communications could always be better. There
has to be lateral and vertical communications
between people in a project. It has to go both
ways," he said. Other
common threads deal with funding, and decisions that
are based on monies available. Also, not having the
right people at the right time can make a
difference, Hughes said. Rausch
said that the reasons behind the loss of the X-43A
were not obvious. "What we're finding is pretty
obtuse," he said. Mach
trial
The
X-43A is one of a trio of test vehicles to be flown
within NASA's $185 million Hyper-X program. The
three vehicles are being provided by Micro Craft,
Inc., of Tullahoma, Tennessee. The
June test was to fly the X-43A to a blistering mach
7 (seven times the speed of sound), or almost 5,000
miles (8,045 kilometers) per hour. The craft carried
a supersonic-combustion ramjet engine, also tagged
as a scramjet. As initially scripted, the Hyper-X
program calls for the second X-43A to also reach the
same speed, while a third craft would zip to mach
10. Sucking
in the atmosphere as it goes, the X-43A combines
that blast of air with a small amount of hydrogen
carried onboard. The hydrogen, blended with the
incoming oxygen, is then combusted and pushes the
vehicle to high-mach speeds. NASA's
Hyper-X program is geared to help build future
generation space launchers. These next generation
boosters are designed to lower the cost and decrease
the operational headache of accessing Earth orbit. "We
continue to learn that when you push the boundaries
of flight, you get surprises," Rausch said.
"We're all disappointed that we had a failure.
But sometimes you learn more from failures than you
do from successes," he added. "It's an exciting program and we're going to fix this bugger and go out and fly it again," Rausch said. |
