Liftoff is slated for 7:00 p.m. EDT (2300 GMT) from SpaceX's Omelek Island launch site on Kwajalein Atoll in the Pacific Ocean's Marshall Islands [image].
"The flight readiness review conducted [Sunday] shows all systems are go for a launch attempt," SpaceX CEO Elon Musk wrote in a mission update to his El Segundo, California-based firm's website, adding that the planned space shot could be delayed "if we have even the tiniest concern."
SpaceX has a four-hour window to launch today's Falcon 1 mission, with additional daily flight opportunities through March 22. A booster equipment concern, since resolved, and range safety personnel issues delayed the planned launch several times.
The only glitch Musk has reported for today's planned space shot involves an anomaly with the global positioning system portion of the Falcon 1's guidance system. The booster is designed to fly primarily on an inertial navigation guidance system, using the GPS system as an aid to refine its path, he added.
Poised to fly
SpaceX's upcoming launch, dubbed DemoFlight 2, is a demonstration for the U.S. Defense Advanced Research Agency (DARPA), which also funded Falcon 1's ill-fated debut in March 2006 [image].
That first Falcon 1 test ended shortly after liftoff after a fuel leak and subsequent fire forced an engine shutdown about 34 seconds into the flight [image]. Initially thought to be the result of human error, the rocket failure was ultimately traced to the corrosion of a small aluminum nut.
Since last year's test, SpaceX has literally made hundreds of improvements to both the Falcon 1 rocket and its ground support facilities on the Kwajalein Atoll, Musk told SPACE.com in a telephone interview.
"We didn't just say we'll go back to the launch pad with the same vehicle and launch again, and see if it works," Musk said. "We really have developed version two of Falcon 1."
The year of improvements has given SpaceX more confidence that, even if today's launch is unsuccessful, the spaceflight firm will be able to recover relatively quickly, Musk added.
"If anything goes wrong with this launch, I wouldn't expect our next launch to be a year from now," Musk said. "We've made every improvement we can think of. I can't think of very much we could do to improve the robustness of the design."
Falcon rocket family
SpaceX's Falcon 1 rocket is a two-stage booster that stands about 68 feet (21 meters) tall and carries a reusable first stage powered by the launch firm's Merlin 1 engine.
Designed to launch small satellites into low-Earth orbit, Falcon 1 rockets are expected to haul payloads of up to 1,256 pounds (570 kilograms) into space for about $7 million per mission, Musk told SPACE.com.
The booster is the first of SpaceX's family of Falcon rockets that includes the Falcon 9 rocket, a heavy-lift launcher currently under development to loft the Dragon crew and cargo capsule. The Dragon and Falcon 9 projects [image] comprise the SpaceX's entry for NASA's Commercial Orbital Transportation System (COTS) to provide crew change and resupply flights to the International Space Station (ISS).
"Falcon 1 is our test vehicle really," Musk said, adding that the technology used in the satellite booster will be upgraded for Falcon 9 launches.
While the primary goal of today's planned space shot is to demonstrate the Falcon 1 rocket's launch capability, the booster is also carrying a pair of experimental payloads, SpaceX officials have said.
Gwynne Shotwell, SpaceX's vice president of business development, has said in the past that the second Falcon 1 rocket will carry a low-cost satellite communications transceiver and an experimental autonomous flight safety system during its upcoming launch.
The mission is the first of at least three scheduled Falcon 1 missions for 2007.
A planned summer launch is expected to orbit the TacSat-1 satellite for the U.S. Naval Research Laboratory, with a follow-up mission to launch Razaksat - a Malaysian Earth-observation satellite - later this year.
"Falcon 1 is intended to be the smallest useful orbital launch vehicle," Musk told SPACE.com.
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