I can't imagine anything more important than air, water, soil, energy and biodiversity. These are the things that keep us alive.

The human brain had a vast memory storage. It made us curious and very creative. Those were the characteristics that gave us an advantage - curiosity, creativity and memory. And that brain did something very special. It invented an idea called 'the future.'

We're in a giant car heading towards a brick wall and everyone's arguing over where they're going to sit.

If we pollute the air, water and soil that keep us alive and well, and destroy the biodiversity that allows natural systems to function, no amount of money will save us.

The future doesn't exist. The only thing that exists is now and our memory of what happened in the past. But because we invented the idea of a future, we're the only animal that realized we can affect the future by what we do today.

Change is never easy, and it often creates discord, but when people come together for the good of humanity and the Earth, we can accomplish great things.

Among the plausible niches for extraterrestrial life in our solar system, the clouds of Venus are among the most accessible and the least well explained.

In environments that are energy-rich but liquid-poor, like near the surface of Titan, natural selection may favor organisms that use their metabolic heat to melt their own watering holes.

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

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

I'd like to jump a couple hundred years into the future and work with the scientists who are getting back the first information from our probes to planets orbiting nearby stars.

There's something cool about being involved in new missions to other planets.

I think the best SF writers are very aware of what we, in the scientific community, are doing, thinking, and discovering.

As a kid, I became a total SF geek. It started in the 5th grade with Asimov's 'Lucky Starr' series of what would now be called 'young adult' novels of adventures in the solar system.

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.

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 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.

We need visions of a future in which we have applied our infinite creativity to the task of living on a finite world, where we have embraced our role, become comfortable and proficient as planet-shapers, and learned to use our technological skills to enhance the survival prospects not just of humanity but of all life on Earth.

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 is said that Mahatma Gandhi, when asked about Western civilization, remarked, 'I think it would be a good idea.' That's how I feel about intelligent life on Earth, especially when I think about the question of what truly intelligent life might look like elsewhere in the universe.

Among the radio astronomers of SETI - the Search for Extraterrestrial Intelligence - it's only sort-of a joke that the true hallmark of intelligent life is the creation of radio astronomy.

Earth is a stunningly lovely planet for so many reasons. Among these is the wondrous presence of curious, artful, inventive humanity.

Whenever I see a nighttime picture of Earth from space, with its glowing lights, I am stirred by its beauty.

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