He was one of the greats of early blogging, and a brilliant man in many fields. I have to confess that I feel partially responsible (though I’m sure I was far from alone) in chasing him away from blogging with an ill-thought email. I think I later apologized, but if I didn’t, Steven, if you can read this, please accept my deepest apologies.
Musk was asked about the reusability of the Falcon 9 rockets currently flying. He stated “I think the F9 boosters could be used almost indefinitely, so long as there is scheduled maintenance and careful inspections.” He emphasized that the current Falcon 9 rockets in production would be retired soon and that their next version would be designed for easy reuse. The new Falcon 9, which he calls “Falcon 9 Block 5” – the fifth and final version in the Falcon series, is scheduled to have its first flight in six to eight months.
I assume the cores for the heavy will be of similar design. I wonder how often “careful inspections” need to occur? Every flight?
We are close to figuring it out. It might have been formation of solid oxygen in the carbon over-wrap of one of the bottles in the upper stage tanks. If it was liquid it would have been squeezed out but under pressure it could have ignited with the carbon. This is the leading theory right now, but it is subject to confirmation. The other thing we discovered is that we can exactly replicate what happened on the launch pad if someone shoots the rocket. We don’t think that is likely this time around, but we are definitely going to have to take precautions against that in the future. We looked at who would want to blow up a SpaceX rocket. That turned out to be a long list. I think it is unlikely this time, but it is something we need to recognize as a real possibility in the future.” [Emphasis mine]
I think that the Arocket list had speculated about this early on.