When last we tuned into the Falcon 1 saga, the launch had been scrubbed for the November 27th date.
“Although we were eventually able to refill the vehicle LOX tanks, the rate at which we could add helium was slower than the rate at which LOX was boiling away. There was no way to close the gap, so the launch had to be called off. In addition, we experienced an anomaly with the main engine computer that requires further investigation and was arguably reason in and of itself to postpone launch.”
First off, the on site LOX production plant is back in action having been repaired. SpaceX has flown two high quality LOX containers to Hawaii and accessed an additional high quality tanker at Hawaii. All are now loaded and on a barge heading back to Kwajalein.
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.
This supply should be able to fill the rocket four to five times over, accounting for almost any situation from troublesome storage tanks to long holds on the launch pad.
The main engine computer reboot anomaly has also been identified and dealt with. It was traced to a ground power outage that resulted from ground resistance in the power umbilical. The umbilical used for the actual launch needed to be longer than was used during testing, three times as long as a matter of fact. Coupled with high temperatures in Kwajalein, it was enough to lower the voltage below minimums causing a computer reset. This situation has also been resolved by increasing the voltage output slightly to compensate.
Importantly, this would have had no effect on flight, since we switch to vehicle power before the autosequence begins.
In an effort to fit in around the Missile Defense Agency, (part of the DOD) tests, a new launch window has been set, contingent on those defense tests being completed as planned. This next possible launch window will be on Tuesday, December 20th with the days on either side of that day being available depending on those DOD tests. The missile range will be shut down for the holidays starting the 22nd, so if for some reason a launch isn’t made during that 19-21 window, a January 2006 date would be the next possibility. Final confirmation of this date and a time will be posted the SpaceX website.
In a soon to be released statement, SpaceX explains some of the misunderstood situations revolving around the LOX problems during the previous launch attempt.
“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.”
SpaceX spokesperson Dianne Molina, explained that unlike the initial press conference announcing the November launch dates, she unexpectedly turned up “short-staffed” for the actual launch. “This time I plan on the teleconference to be bigger, better and run more smoothly.”
So, with that said, let’s pencil in the new launch window and get ready for “Live-Blog II: The Saga Continues.”
“This Bird Will Fly…”