* Astronomy

T minus 5 minutes

The countdown has gone into hold.

T-minus 10 minutes and counting.

All systems have passed their prelaunch checkout and the Falcon one is ready for launch 19:00 GMT, today.



The hold down firing countdown will begin at T minus 3 hours.

The new launch date is around December 19-20, depending on when the Missile Defense Agency testing is complete.

Liquid oxygen (LOX) supplies will be 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.
SpaceX has chartered a C-17 to fly two of their 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, their LOX plant on Kwajalein has been repaired and is producing LOX on island again.

SpaceX ran out of LOX on the remote tropical island on the last launch attempt because of several issues:

* 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 they could not top up.
* They ordered replacement LOX from Hawaii, but the container quality was poor, so only 20% of what they 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 the final storage tank did not have a small, manual vent valve incorrectly in the open position. Somewhat agonisingly, they were only a few percent away from being full.
* After a while, they were able to close the vent and fill the vehicle's LOX tanks. However, they use LOX to chill the 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, they did not have enough LOX to stay filled on the rocket and chill & pressurise the helium.

The engine computer reboot anomaly was definitively traced to a ground power problem. Importantly, this would have had no effect on flight, since they switched to vehicle power before the autosequence began. The reason it cropped up at Kwajalein was that the higher load on the longer umbilical (three times longer than in prior tests) coupled with high temperatures in Kwajalein resulted in increased resistance in the ground umbilical. This was just enough to lower the voltage below minimums and cause an engine computer reset when drawing maximum power. The same max power test was repeated on internal vehicle batteries with no problem at all.

This problem has been solved by slightly increasing voltage on the ground umbilical.