It's critical that NASA think very hard about these unmanned science missions continuing.

181

The hardest choices we had to make was deciding what to leave out. What happens when an icy meteor hits the Earth is different than when an iron meteor hits the Earth. But we had to leave out some things.

162

Whether there's enough heat to actually get the chemistry [of life] going is pure speculation at this point. But it's certainly intriguing.

148

Its a subject that's near and dear to my heart.

107

It wouldn't be cheap to do. But having an asteroid hit us wouldn't be cheap either.

59