[sehugg]

Musk attributed it to low levels of triethylborane—a hot-burning propellant that essentially acts as rocket engines' starter fluid—in the center booster.

The center core is a special structurally enhanced model, so I'll give them a pass since they're flying a new bird. I'm sure they'll get it right.

[mabbo]

That makes a lot of sense. The center core had to ignite for liftoff, then either scale back or stop entirely during the main lift phase, then re-ignite when the side boosters detached, then reignite for the boostback, entry AND landing burns. That's a lot of re-ignition!

I hope they post a very high quality video of that booster having its unplanned disassembly. May not be great for PR, etc, but it sure would be entertaining.