After the successful ORBCOMM OG2 mission on a Falcon 9 v1.1 Full Thrust (aka 1.2, aka 'just' Falcon 9) and the recovery of its first stage at LZ-1, SpaceX indicated it survived well, and trucked it to the HIF (Horizontal Integration Facility) at LC-40.
SpaceX initially said they intended to hot fire the stage to demonstrate the engines were still good, even after a full flight including RTLS, at LC-39A. This had the added benefit of not affecting flight operations at LC-40, and would allow some dry runs, with no real time constraints for LC-39A.
But then, suddenly, images of the stage on a truck, driving to LC-40 arrived (Imagine the F-9 stage 1 as Slim Pickens and the truck as the nuclear bomb) on the web. Then we found out they were going to hot fire it at LC-40, and sneak it in before the SES-9 launch end of January.
After the move, we started to hear that the SES-9 flight was delayed for undisclosed reasons. But regardless, why the switch from LC-39A to LC-40 for the hot fire?
Possible theories abound:
- LC-39A ground support equipment (GSE) not ready
- LC-39A supply of LOX/RP1 not ready, or not on hand in time.
- Other LC-39A issues.
- With delay of SES-9 known earlier to SpaceX, LC-40 was free and would provide another dry run of the GSE for sub-cooled LOX and RP1 adding to the confidence of an on-time launch for SES-9