SpaceX is performing the first launch of its privately funded Falcon 1 rocket from the South Pacific island of Omelek in the Kwajalein Atoll. Kwajalein, in the Marshall Islands, is the home of the US Army's Reagan Test Site, which supports ballistic missile and missile defense testing.

According to SpaceX, last month's launch attempt was scrubbed when helium, used as pressurant in the Falcon, was depleted after LOX (liquid oxygen) being used to cool it was accidentally vented from an auxiliary fill tank, as SpaceX CEO's Elon Musk, wrote, last Friday in a statement:

'Regarding liquid oxygen (LOX) supplies, we expect to have enough on hand this time to fill the rocket four or five times over'.

'This should account for almost any issue with a particular storage tank as well as an extended hold on the pad. There is an engineering term known as a s*load. I have asked that we have at least two s*loads on hand in case one s*load is not enough'.

'We chartered a C-17 to fly two of our empty high quality LOX containers to Hawaii, sourced another high quality LOX container on Hawaii and put all three on the barge to Kwajalein. In addition, our LOX plant on Kwajalein has been repaired and is producing LOX on island again'.

'Some might be wondering why we were so dumb as to run out of LOX on a remote tropical island on the last launch attempt. Believe me, we tried hard to avoid it, but several issues conspired to create the problem:

'The additional month of Merlin testing resulted in additional LOX boil-off on island. Even though it is stored in vacuum jacketed containers, LOX at -300F degrees does not like being on a tropical island at 85F.

'The SpaceX LOX plant on island broke down a few weeks prior to launch, which meant we could not top up.

'We ordered replacement LOX from Hawaii, but the container quality was poor, so only 20% of what we ordered actually arrived'.

'Ground winds were unusually high on launch day, which amplifies the boil-off rate significantly, since the Falcon's first stage LOX tank is uninsulated. All of the above would not have mattered if our final storage tank did not have a small, manual vent valve incorrectly in the open position. Somewhat agonizingly, we were only a few percent away from being full. We just needed a little sip from the last tank.

'After a while, we were able to close the vent and fill the vehicle's LOX tanks. However, we use LOX to chill our onboard helium and the absence of ground LOX to do so resulted in the helium heating up and venting back to storage. In the end, we did not have enough LOX to stay filled on the rocket and chill & pressurize the helium'.

In addition, AstroExpo.com reports that an unspecified problem with the main engine computer was uncovered during the countdown that, according to SpaceX CEO, Elon Musk, "requires further investigation and was arguably reason in, and of itself, to postpone launch."

Launching from Omelek is a key part of SpaceX's business strategy for the Falcon 1 and its larger follow-on rockets, the Falcon 5 and Falcon 9. Because of its near-Equatorial location (9.5 degrees North) and the unparalleled range support that the Reagan Test Site provides, SpaceX sees Omelek as an attractive and enabling launch site for much of its military and commercial traffic, reports AstroExpo.com. The island's remote location also allows SpaceX to launch in virtually any desired direction, giving them a great deal of flexibility in mission planning.

The December 19-21 launch window is contingent upon a planned Reagan Test Site missile defense test being completed on schedule. The range will shut down for Christmas on December 22, reports AstroExpo.com, moving the next launch attempt to January 2006 at the earliest.

The Falcon's first flight will carry a small satellite � coincidentally called Falconsat II � built by students at the US Air Force Academy. The satellite, a one-foot cube weighing less than 50 pounds, is to be launched into a 39-degree, 400 x 500 km (248 x 310 statute mile) orbit. The small satellite represents only a few percent of the Falcon's billed payload capacity to that orbit.

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