If NASA is to reach beyond the Moon and someday reach Mars, it must be relieved of the burden of launching people and cargo to low earth orbit. To do that, we must invest more in commercial spaceflight.

What happens to other species also happens to us.

Millennial voters are very concerned about climate change and will vote for candidates who are planning to address it. But the systems that are in place - people talk about gerrymandering and the money that's in politics, this is a real thing, a real effect - and it's hard for climate change-denying legislators to get voted out. But I predict it will happen.

People that don't want to get down to the business at hand. Instead of just doing less, we have to find ways of doing more with less. That's the key to the future.

Recommending or insisting on abstinence has been completely ineffective.

Hard to find anything lovelier than a tree. They grow at right angles to a tangent of the nominal sphere of the Earth.

The most serious problem facing humankind is climate change.