A timing
error that caused two segments of a privately built Falcon 1 rocket to collide
after liftoff doomed the booster's third flight test by the California-based
firm SpaceX, company's chief said Wednesday.
SpaceX CEO
Elon Musk said his engineers have traced the cause of the Aug.
2 launch failure to a timing error between the shutdown of the low-cost Falcon
1 rocket's first stage engine and the separation of its upper stage, leading
the two segments to bump into one another instead of separating harmlessly.
"We have quite
a definitive understanding of what went wrong on the last flight," Musk told
reporters in a teleconference, adding that the timing error was on the order of
seconds. "If we were to increase that gap by even a second or two, this problem
would not have arisen."
Based in
Hawthorne, Calif., SpaceX — short for Space Exploration Technologies — launched
its third Falcon 1 rocket late Saturday EDT from the U.S. Army's Reagan Missile
Test Site on Omelek Island in the Kwajalein Atoll, which sits about 2,500 miles (4,023 km) southwest of Hawaii in the central Pacific Ocean.
Musk said
SpaceX would be releasing video of the staging event that clearly shows that
the first and second stages separated as planned about 2 minutes and 20 seconds
into the flight, but that unanticipated residual thrust from the redesigned
Merlin engine caused the first stage to bump the second stage just as it began
to fire.
Both halves of the rocket then fell into the Pacific Ocean well east
of the U.S. Marshall Islands and were destroyed along with its payload of two small NASA satellites and the Trailblazer demonstration satellite for the Pentagon. A container containing the cremated remains of people, including those of astronaut Gordon Cooper and actor James Doohan of television's "Star Trek", who had paid to have their ashes launched into space was also lost, according to the space memorial firm Celestis, Inc.
The rocket was
powered by SpaceX's Merlin 1C engine, which uses a regenerative cooling system
that funnels propellant through a series of channels along its engine nozzle before
ignition. Previous Merlin engines used ablative cooling systems that burned
away material to shed excess heat.
Musk said
that simply extending the Falcon 1 rocket's 1 1/2-second separation sequence
should solve the problem. SpaceX engineers pinned the glitch down for sure on
Tuesday and are determined to aim for orbit a fourth time, he added.
"If we had
a rocket on the launch pad tomorrow we could make this timing change, launch
and be okay," Musk said.
The recent
failure marked the third in a row for SpaceX since the Falcon 1's debut in
March 2006, when a fuel
line leak and fire thwarted the inaugural launch just after blast off. A 2007
test flight lasted about five minutes, enough to undergo
stage separation, before it also failed.
Musk said
that in contrast to the second test, which found other potential problems after
analysis, SpaceX's post-launch assessment of the Aug. 2 flight has found no
other near-miss issues that need to be worked before the next launch. As a
result, Musk is confident that Falcon 1 will be flying again before the end of
the year.
Components
for the fourth Falcon 1 rocket to are expected to head to SpaceX's Omelek Island
launch site in a few weeks, Musk added.
SpaceX's
Falcon 1 rocket is a two-stage booster that stands about 68 feet (21 meters)
tall and carries a reusable first stage designed to be recovered in the ocean
and refurbished for future flights. The $6.7 million rocket is designed to loft
satellites up to 1,256 pounds (570 kg) into low-Earth orbit.
The rocket
is the first of SpaceX's family of Falcon boosters, with engine test firings
also underway for the larger Falcon 9 launch vehicle.
As it
stands, SpaceX expects to have its next Falcon 1 in place for a fourth launch
attempt as soon as September.
That launch
will now be a demonstration launch, Musk said, since SpaceX had previously
promised to its next customer, the Malaysian space agency, that it would prove
Falcon 1's ability to reach orbit before attempting to launch the company's
Razaksat spacecraft.
"I've never
given up and I've never lost," Musk said. "And I'm not going to start now."
Space News
Staff Writer Brian Berger contributed to this story from Washington, D.C..
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