WASHINGTON
- A tiny weld defect discovered in one of the Falcon 1's engine nozzles as the
rocket was being readied for a late June launch contributed to Space
Exploration Technologies' (SpaceX) decision to postpone its third attempt to
put the rocket into orbit by at least a month.
Elon Musk,
founder and chief executive officer of the Hawthorne, Calif.-based rocket-start
up, said June 27 that the defect was so tiny - about a tenth of millimeter -
that it passed inspection before shipment and was unlikely to cause a problem
during launch.
"By our
calculations and by our tests that should be safe for flight," Musk said.
"However, in the interest of paranoia we are going to change the nozzle."
Musk said the weld defect was
discovered at the launch site in mid-June just prior to Falcon 1's stages being
mated together in preparation for rolling the rocket out to the pad.
SpaceX had been targeting a late
June liftoff from the U.S. Army's Reagan Test Site in the central Pacific
Ocean.
Army
Missile Command spokesman John Cummings said Reagan Test Site officials
reserved June 24 to June 30 for a Falcon 1 launch from Omelek Island in the
Kwajalein Atoll and extended that window to July 3 before granting SpaceX's
request to push off until late July. "They came back to us and said they could
launch no sooner than 29 July," Cummings said.
Musk said the
flawed nozzle can be replaced on Omelek, but requires moving the rocket back
into the hangar and de-mating the stages. "We can do that a lot sooner than
July 29 but the problem is we couldn't get a launch date after July 3 until
July 29," he said.
Musk
declined to provide more detail about all that went into SpaceX's decision to
forfeit the late-June through early-July window he had booked for Falcon 1. But
in a June 25 press release announcing the successful completion earlier that
day a full launch dress rehearsal and hold-down firing, Musk was quoted saying,
"we are definitely not tied to the clock for this launch, and we are checking
and cross checking every aspect of the vehicle and ground systems to ensure a
successful mission."
SpaceX has
made two previous attempts to put Falcon 1 in orbit. The first attempt, in
March 2006, ended in
failure about a minute into flight due to a fuel line leak and subsequent
fire eventually traced to a corroded nut. During its
second attempt, in March 2007, the Falcon 1 reached an altitude of 289
kilometers and near orbital velocity before the rocket's second stage engine
shut down due to a roll control issue attributed to fuel slosh.
The primary
payload for the upcoming launch is a small
satellite called Trailblazer built on short notice by Poway, Calif.-based
SpaceDev for the Pentagon's Operationally Responsive Space Office.
The
Pentagon had three candidate payloads for the upcoming Falcon 1 launch and held
off until June telling SpaceX which one it had picked in order to test the
company's ability to integrate a payload with the rocket with just two week's
notice.
Musk said the Trailblazer was
integrated on time along with two smaller NASA-provided payloads providing the
quick turnaround time the Pentagon wanted SpaceX to demonstrate.
Explaining the decision to fall back
to a window that runs July 29 to Aug. 6, SpaceX said in its June 25 press
release the Reagan Test Site would be closed for the U.S. Fourth of July
holiday and resume operations July 24. Two days earlier, the Web site Spaceflight
Now reported critical range assets were booked through July, attributing
that information to Musk.
One
Kwajalein official told Space News the range would be open and available
throughout July with no launch activity on the schedule "unless there's a black
program going on that I don't know about."
Cummings
confirmed that the range would remain open throughout July, but said he did not
know whether it is available to SpaceX sooner than July 29. "We haven't looked
because they did not ask for it," he said.
Musk said
SpaceX was mistaken to say the range would be closed in July. "I probably used
the wrong word there and should have said 'not available to us.' Maybe they are
not 'booked' and maybe they are not 'down' but they are not available us," Musk
said.
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