If we have the power to turn another planet into Earth, then we have the power to turn Earth back into Earth.

One of the things that fascinates me most is when people are so charmed by the universe that it becomes part of their artistic output.

God is an ever receding pocket of scientific ignorance.

My view is that if your philosophy is not unsettled daily then you are blind to all the universe has to offer.

I'm not writing for myself. I'm writing as an educator, I'm writing to stimulate others.

The value of the space program is beyond science, it's beyond military; it's a cultural shift in how we think of our place in the universe.

Private enterprise can never lead a space frontier. It's not possible because a space frontier is expensive, it has unknown risks and it has unquantified risks.