SpaceX Rocket Countdown Rehearsal A 'Great Success'

Taking advantage of a picturesque day in the Sunshine State, the privately-developed Falcon 9 rocket came to life Friday afternoon as engineers loaded 75,000 gallons of propellant aboard the vehicle during a simulated countdown.

Friday's countdown wet dress rehearsal was "the smoothest test we have conducted to date," said Tim Buzza, the Falcon 9 launch director.

The booster has spent the last week at Complex 40 after being assembled inside a hangar at the pad's southern perimeter. Stormy weather and high winds earlier this week pushed the countdown rehearsal to Friday.

After powering up the 15-story rocket, the launch team verified all systems were functioning, performed engine purge checks and cleared workers from the launch pad.

About 29 managers and engineers inside SpaceX's Launch Control Center oversaw the countdown, which began at the T-minus 2 hour, 30 minute point.

The transporter/erector, also serving as an umbilical tower and strongback, was partially tilted away from the rocket around 1:30 p.m. EST. Liquid oxygen started flowing into the two-stage Falcon 9 launcher at about 3 p.m. EST.

The super-cold oxidizer was loaded into the rocket until the first and second stage tanks were 98 percent full, then the launch team topped off the liquid oxygen to liftoff levels, where they remained throughout the countdown, according to SpaceX.

The shining white rocket was coated in ice after liquid oxygen was placed on-board.

The Falcon 9 was next filled with kerosene fuel, which powers Merlin engines on both stages of the rocket.

In the final 10 minutes of the countdown, the Falcon 9's navigation system was aligned for launch, the rocket was transferred to internal power, the engine steering systems were checked out, and propellant tanks were pressurized at T-minus 40 seconds, according to Buzza.

The countdown clock was stopped at T-minus 10 seconds around 5:15 p.m. EST using the pad abort system.

After safing the rocket and launch pad, SpaceX drained the Falcon 9 of propellant and raised the strongback next to the launcher.

"It was a good day," said Elon Musk, SpaceX's founder and CEO.

Engineers will spend the next few days carefully reviewing data from Friday's test. If the results prove satisfactory, SpaceX plans to fuel the rocket again in the coming weeks for another countdown rehearsal that will end with a brief ignition of the Falcon's nine first stage engines for about three-and-a-half seconds.

Unlike Friday's practice countdown, which was unannounced, the engine test will send an unmistakable roar across the Florida spaceport.

The launch date for the inaugural Falcon 9 rocket mission remains unclear, but it is not expected to occur before March 22. The demonstration flight's launch window opens at 11 a.m. EDT each day.

SpaceX is developing the Falcon 9 rocket and a spacecraft named Dragon under a NASA contract to deliver supplies to the International Space Station beginning next year.

Since its founding in 2002, SpaceX has launched the smaller Falcon 1 rocket five times, reaching orbit twice.

The company is considered a frontfrunner among commercial firms competing for the job of carrying astronauts to the International Space Station under NASA's new emphasis on private human spaceflight.

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