I realized that a methane-oxygen rocket engine could achieve a specific impulse greater than 380.

There's a tremendous bias against taking risks. Everyone is trying to optimize their ass-covering.

The first step is to establish that something is possible; then probability will occur.

My family fears that the Russians will assassinate me.

The biggest mistake, in general, I've made, is to put too much of a weighting on someone's talent and not enough on their personality. And I've made that mistake several times. I think it actually matters whether somebody has a good heart, it really does. I've made the mistake of thinking that it's sometimes just about the brain.

Focus on something that has high value to someone else, be really rigorous in making that assessment, because natural human tendency is wishful thinking, so the challenge to entrepreneurs is telling what's the difference between really believing in your ideals and sticking to them as opposed to pursuing some unrealistic dream that doesn't actually have merit, be very rigorous in your self analysis, certainly being extremely tenacious, and just work like hell. Put in 80-100 hours every week. All these things improves the odds of success

I've always wanted to be part of something that would radically change the world. . . . People forget the power of inspiration. All of humanity went to the moon with the Apollo missions. The issue was cost. There was no chance to build a base and create frequent flights. That's the problem I would like to solve.