This was recently posted on /r/spacex:
(Tom Mueller interview/Skype call)
Couple of SpaceX related highlights:
They avoid space vendors
Block 5 will have reusable TPS and better landing legs that can fold for transport
Elon on Merlin engines: Why do they cost more than a model S when they weight 1/5 as much?
SpaceX has forced other LPs to innovate, reuse.
Raptor designed to 99% thermal efficiency
30% of F9 cost is upper stage
Videos claiming that SpaceX faked landing are highest compliment (because they are claiming that what you are doing is impossible)
>4000psi combustion chamber pressure
Methane is much cheaper than kerosene
1000t of propellant needs to be manufactured on Mars over 2 years to get home
Elon wanted 12h F9 turnaround, settled for 24h
Electric prop for sats
SpaceX is looking at nuclear thermal, prohibitively expensive for SpaceX to develop due to environmental laws, if NASA every works on it SpaceX would "jump in"
Raptor is 3.5, 3.6 O/F ratio
ITS could do jupiter direct with about 20t payload, no people without depots
SpaceX is enabling "killer space apps"
Working for Elon Musk is "pretty trippy" "different every day" "extremely demanding" tends to take the harder way
Merlin uses "phase shutoff" Mueller advised Elon against it (removes many valves, some computers, harder R&D with many RUDs on test stands)
SpaceX is following NASA planetary protection protocols, initially
He also describes a rocket engine as "Throwing 800lbs of bricks at mach 10 every second"