The astrobiologist Nathalie Cabrol was born in 1963 and grew up near Paris. She completed a PhD at the Sorbonne on the evolution of water on Mars and moved to the US in 1994 as a researcher at NASA Ames. She has worked extensively in the Atacama Desert and the Chilean Andes, exploring how life adapts to extreme environments similar to those on other planets. Cabrol, who lives in Northern California, is now director of the Carl Sagan Center at Seti [Search for Extraterrestrial Intelligence] Institute. Her latest book, The secret life of the universe: An astrobiologist’s quest for the origins and limits of lifepublished on August 15.
How did you get interested in the skies?
It is not difficult to be interested in the heavens, we are in the heavens! I remember looking up at the sky, at the age of five or six, and starting to wonder, “What is this for? Why does this exist?”
When searching for extraterrestrial life, is it wrong to search alone? Earth-like planets and life as we understand it?
It’s not necessarily bad to look at our biochemistry and the kind of environment that got us here. Astronomy is telling us that the stuff we’re made of is so common, and we’re learning that carbon was created much earlier than we thought. And with the discovery of exoplanets [planets outside our solar system], we are also realizing that, although there is probably no exact replica of Earth anywhere in the universe, there are environments that are probably just as suitable for life, or more so. But from this point of view, we are hindering ourselves in the search for another version of ourselves. I’m looking more at universal markers of life – markers that would be true anywhere in the universe, regardless of biochemistry.
What makes you so sure there is something there, rather than nothing?
The easy answer is Carl Sagan’s: “That would be a terrible waste of space.” We’ve been searching for life intellectually for thousands of years, but searching meaningfully with technology for only 60 years, so this is very new research. Also, you need to look at the distances. Even if by some miracle [alien life forms] are thinking and communicating in ways similar to us and are interested in what is going on around them, our radio bubble is barely 200 light years in diameter. This is small. Then there’s the fact that we’re in search of life, but we don’t really know what life is, or intelligence, or even less consciousness. We have no idea what those three things are. We’re still looking for them, which is okay, because otherwise it goes nowhere.
Where in our solar system would you most expect to find life blowing?
I believe that Mars still has some big surprises for us. They won’t be on the surface, but unlike many people I don’t think it will be that far below. There is still volcanism on Mars and we know there is water and lots of nutrients – magnesium, potassium and so on. Elsewhere in the solar system, Europa [a moon of Jupiter] there might be an oxygenated ocean that might offer a chance for more complex life to develop. It also has carbon resources.
We are talking about oceans under kilometers of surface ice.
Yes. And the thing is, you don’t need to invest in submarines to explore it; you can let mother nature bring things to you. Because of the gravitational tides in Europa, you have these convective movements and a kind of slush that regularly comes to the surface. Drop down next to it, grab those things and see what’s there. Let the ocean come to you.
But Enceladus [a moon of Saturn] it’s definitely my favorite. I like it because it’s just throwing things at you in geysers or plumes [shooting up from the surface]. Obviously, it’s pretty complicated to slow down a spacecraft to grab samples, but we can do incredible things on Enceladus.
Do other planets teach us lessons about what to expect? global warming on Earth?
When you look at what happens to a planet when you have a runaway greenhouse effect, then that’s Venus. And the planet that’s so hot that it’s losing its water, that’s Mars. We have it before our eyes.
What is your view of people? such as Elon Musk talking about colonizing other planets?
Well, first of all, I hate the word colonization. And the idea of setting up outposts on another planet because we’re getting rid of our own is an affront to the spirit of exploration. Immigrants usually move because they are desperate for better conditions. This is not the case on Mars. It’s much worse. I think we should go to Mars not because it is an easy escape, but because we have grown up and are using it as a training ground for a much older civilization to take its first steps towards interplanetary transition, and later, interstellar. But we also have to use all that technology to look back at Earth.
Projecting ourselves into space is challenging our brains to find solutions we wouldn’t otherwise look for on our planet. Of course, sending a Tesla into space [as Musk did in 2018] it wasn’t the right message when you’re trying to create space policy and prevent planetary contamination.
There has been a lot of excitement about UAPs [unidentified anomalous phenomena] recently. Do you pay too much attention?
As a scientist, UAPs are interesting to me because we must first take them for what they are: unidentified phenomena. The leap I’m not making is to say that they are necessarily extraterrestrial phenomena, as in flying saucers, etc. We know that 96% of them will find a natural explanation. One thing to consider is that we are seeing many more unusual atmospheric phenomena because our planet is changing. And then there are undisclosed government activities that you weren’t supposed to see. Finally, it is the half percent or more that is unexplained. Of course I’m interested.
But Seti isn’t into aerial phenomena—our instruments are pointed much further away. I always say, jokingly, that we are looking for ET in its own habitat, while people looking for UAP are trying to see ET in ours. But if you tell me tomorrow that you have irrefutable evidence of an alien spacecraft being caught on video somewhere, I will be the happiest man in the world.