SpaceX's irrepressible
Elon Musk has posted an occasionally tongue-in-cheek update as to
the condition and prospects for a launch of their
several-times-delayed Falcon 1 launch vehicle. Delayed by a
multitude of small problems and the inherent difficulties in
launching from a (very) remote location, hopes are high for a
launch of the Falcon 1 later next week. Herewith, Elon's complete
report...
Launch Date
The new launch date is approximately December 20, depending on
when the Missile Defense Agency testing is complete. As soon as we
have a firm time, it will be posted on the SpaceX website.
Liquid Oxygen
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.
Engine Computer
The engine computer reboot anomaly was definitively traced to a
ground power problem. Importantly, this would have had no effect on
flight, since we switch to vehicle power before the autosequence
begins. 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.
--Elon--