Astrobiology is the science of life in the universe. It's an attempt to scientifically deal with the question of whether or not we're alone in the universe, looking at the past of life, the present of life, and the future of life. It's an interdisciplinary study incorporating astronomy, biology, and the Earth sciences.
David Grinspoon
Humans are possessed, to some degree, with the power of foresight. Yet we so often learn things the hard way, through disaster.
The hallmark of the human species is great adaptability.
As Earth's climate changes, we can expect more destructive hurricanes. As sea level and surface temperatures rise, more solar energy is trapped in the atmosphere, revving up the hydrological cycle of evaporation and precipitation and sometimes manifesting in terrifying storms.
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.
What if life is not carbon-based? Can life exist as a gas or a plasma? Could planets or stars in some sense be alive? What about an interstellar cloud? Could life exist on such a small or large scale, or move so fast or so slowly that we wouldn't recognize it? Could you have an intelligent virus?
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.
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.
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.
Our most valuable resources - creativity, communication, invention, and reinvention - are, in fact, unlimited.
There is a real danger of unintended consequences, of encouraging people to give up. Pessimism, if it becomes a habit, can reinforce a narrative of unstoppable decline. If there is nothing we can do, that releases us from our obligations.
It's OK to pursue speculative ideas because we don't want to be too cozy and safe and assume that we know everything about life in the universe. However, we have to be rigorous and careful and honest and logical and scientifically meticulous when we speculate.
NASA, and all the other spacefaring nations of the world, have agreed to a set of 'planetary-protection' principles, aimed at preventing the accidental contamination of another habitable world with organisms from Earth.
Radiation is one of the important factors in evolution. It causes mutation, and some level of mutation is actually good for evolution.
Earth's biosphere gave birth to humans and our thoughts, which are now reshaping its planetary cycles. A planet with brains? Fancy that.
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.
Seriously, we should start taxing churches and have tax-exempt places for worship and study of nature and art. Charge ten bucks for Sunday services and make the Botanic Gardens free.
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.
It turns out one of my dad's best friends was Carl Sagan when I was little. They were both Harvard professors.
Once we become a multiplanet species, our chances to live long and prosper will take a huge leap skyward.
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.
I do a lot of work with NASA and am involved in research projects studying planetary evolution, Earth-like planets, and potential conditions for life elsewhere.
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.
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.
What we should really be thinking about is what it would look like for a truly intelligent technological species to be interacting with their planet's atmosphere.
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.
I think the best SF writers are very aware of what we, in the scientific community, are doing, thinking, and discovering.
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.
There are other planets besides the Earth and Mars. I'd like to remind you that studying Venus is vital to understanding life elsewhere.
Why should we consider defining intelligence as something global and as something that hasn't actually yet appeared on Earth? It may be useful for envisioning the future of our own civilization and any others that may be out there among the stars. It might give us something to strive for.
Ever since the environmental movement was sparked by photos of the whole Earth taken by astronauts onboard Apollo Lunar Modules, I've seen planetary exploration as an extension of a reverence and care for Earth.
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.
As a young planet, Venus was losing hydrogen rapidly to space. The oceans boiled off, and after some period of time, perhaps 600 million years, there was no surface water.
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'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.
When I first went to college, I went into physics, and my goal was to help perfect nuclear fusion so I could solve the energy crisis and global warming. I probably would have done it, too, if I'd stuck to it.
We definitely don't want to go through another Ice Age or another natural cycle of global warming. Both happen over a long period of time. It would be disastrous for our civilization, and not just for us but many other species.
What I'm interested in is the conversations going on about the Anthropocene and what it means to view ourselves as a part of Earth's geological history.
We have to learn to become a new kind of entity on this world that has the maturity and the awareness to handle being a global species with the power to change our planet and use that power in a way that is conducive to the kind of global society we want to have.
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.
There's eco-pragmatism, where you recognize, 'Yeah, we live on a planet that's permanently altered by humanity, and rather than seek to return to or preserve pure wilderness, we recognize that's an illusion, and we proceed under the new knowledge that we live, in fact, in a human-dominated planet.'
One of the weird things about modern physics is that we do find there are apparently these other dimensions that we don't directly experience that explain some aspects of the overall geometry and reality of our universe.
I think Pluto has to be considered among the places in the solar system that are possible homes for life.
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.
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.
If we gutted NASA Earth Science, it wouldn't be NOAA or some other agency that would take the lead. It would be the Chinese and the Europeans and the Japanese.
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.
I think chemists always think they know more than they know, because nature has a lot of possible pathways it can try.
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.
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.
