David Grinspoon

“It's quite possible there's as much lightning on Venus as on Earth.”

“In my Ph.D. thesis, written in 1989, I discussed the fact that when a civilization develops the technology to prevent catastrophic asteroid impacts, it marks a significant moment in the evolution of the planet.”

“The future peopling of Mars is much more than a scientific endeavor. It is a step of historic and spiritual importance for the human race.”

“Through space-based climate studies, my colleagues and I have learned that a stable and comfortable climate is not something to take for granted.”

“I think chemists always think they know more than they know, because nature has a lot of possible pathways it can try.”

“It's one of the big mysteries about Venus: How did it get so different from Earth when it seems likely to have started so similarly? The question becomes richer when you consider astrobiology, the possibility that Venus and Earth were very similar during the time of the origin of life on Earth.”

“It will be a long time, if ever, before we get to study Earth-like planets orbiting around other stars, so really, the study of Venus and Mars is the best opportunity that we have, and can imagine having anytime in the future, to understand the evolution of Earth-like planets.”

“Even as a kid enthralled with science fiction, I wondered about the role of people in the long-term evolution of the Earth, the far future and the fate of humanity.”

“I was a science fiction geek from an early age, enthralled by the questions of life in the universe. As I got older, I learned that space exploration was real. I wanted to get involved in that. I knew I wanted to be a scientist.”

“Earth is going to lose its oceans in the future, just as Venus did in the past. How long planets retain their oceans is a function of distance from the sun, all other things being equal.”

“If you were on the surface of Venus, assuming you could see the Sun, which, you know, would be hard because it's so cloudy there, but the Sun would actually rise in the west and set in the east. And, it would do so very, very slowly, because the planet rotates incredibly slowly.”

“The mature Anthropocene begins when we acquire the ability to live sustainably and become a lasting presence on this world.”

“Certainly for me, as an astrobiologist, science fiction has played an important role. One of the quandaries of our field is that we are trying to study and search for something - life - that we can't define in a rigorous way. We only have one example of a biosphere, so we can't really give a good definition.”

“There was a long history of people believing there was life on Venus. It was about the same size as Earth. It had clouds. It was commonly believed it was tropical - wet, hot and steamy.”

“Now, humans have become a dominant force of planetary change and, thus, we may have entered an eon of post-biological evolution in which cognitive systems have gained a powerful influence on the planet.”

“There is a history of thinking about space science from an environmental ethics perspective. And part of what I want to do is turn that back and use that experience to see if it reflects how we think about the Earth.”

“There's no question to my mind that saving our civilization and many other species is more important than our ability to do ground-based astronomy for a few decades.”

“It turns out one of my dad's best friends was Carl Sagan when I was little. They were both Harvard professors.”

“You cannot study other planets without referring to Earth and without applying the techniques and the insights of Earth science. And you cannot really do a good job understanding the Earth without the insights from planetary exploration.”

“I don't see it as coincidence that the great acceleration of the Anthropocene influences on Earth came during the same decades as our first exploration of the other planets.”