David Grinspoon

“When you think about alien intelligences making art, you then have to think about what art is and how bound up it is in the nature of consciousness. Why do we make art? And what can we expect to have in common with other creatures in universe?”

“The more we look at the kinds of soils and the nature of the atmosphere and the polar caps, it all adds up to tell us that some liquid, which we very much believe was water, did flow in abundance on Mars in the past.”

“Titan has rivers and lakes of liquid methane and ethane, methane weather systems of clouds and storms that mirror Earth's hydrologic cycle, and seasonal cycles that rival Earth's in complexity.”

“The reason you see so many volcanoes on Venus is partly due to the fact that there's virtually no erosion there. So on Venus, you're seeing features, some of which are hundreds of millions of years old on the surface. On Earth, we do not see any surface features nearly that old - you only see much more recent features.”

“I'd been politically active ever since my parents wheeled me in a stroller in a 'ban the bomb' march in Boston in 1963.”

“I think a lot of people interested in space exploration tend to hear stories about the great missions, how they work technically, what we learned. But they don't really hear the story of what it takes to get a mission from scratch to the launch pad and into space.”

“Our most valuable resources - creativity, communication, invention, and reinvention - are, in fact, unlimited.”

“We're going to get off fossil fuels, no question. We may not do it quickly enough to avoid some pain, and I'm quite worried about that. But by the 22nd century, there's no way we'll be on fossil fuels.”

“The basic ability to not wipe oneself out, to endure, to use your technological interaction with the world in such a way that has the possibility of the likelihood of lasting and not being temporary - that seems like a pretty good definition of intelligence.”

“Time and time again, our species has escaped existential threats by reinventing ourselves, finding new skills not coded in our genes to survive new challenges not previously encountered.”

“Earth's biosphere gave birth to humans and our thoughts, which are now reshaping its planetary cycles. A planet with brains? Fancy that.”

“Once we become a multiplanet species, our chances to live long and prosper will take a huge leap skyward.”

“Literally, my earliest memory, my earliest vivid memory, is the Apollo 11 landing on the Moon. Yeah, I was in fourth grade, and I was just so captivated. And I think you'll find a lot of space scientists of my generation will say the same thing. Apollo was a big event for them.”

“Venus and Mars are our next of kin: they are the two most Earth-like planets that we know about. They're the only two other very Earth-like planets in our solar system, meaning they orbit close to the sun; they have rocky surfaces and thin atmospheres.”

“We can look out on an alien landscape that no one has seen before and find it beautiful.”

“Astrobiology is a great point of contact for science outreach. The public is naturally interested in extra-terrestrial life. Astrobiology provides an accessible point of access that leads to deeper questions.”

“Thinking about the new epoch - often called the Anthropocene, or the age of humanity - challenges us to look at ourselves in the mirror of deep time, measured not in centuries or even in millennia, but over millions and billions of years.”

“My high-school friends and I felt part of a community of smart, forward-looking space and technology freaks.”

“It's quite possible that the end of us will not be the end of the Earth. Even if we really screw things up and things go badly for us and our civilization, the Earth is pretty resilient.”

“I think Pluto has to be considered among the places in the solar system that are possible homes for life.”