As a teenager in Spain, Alberto Gonzalez Fairén watched US astronomer Carl Sagan's television series Cosmos, read the book based on the series and knew that he wanted to be a scientist. He is now an astrobiologist at the SETI Institute's Carl Sagan Center for the Study of Life in the Universe in Mountain View, California, and the NASA Ames Research Center in Moffett Field, California. In October, Fairén will collect the Harold C. Urey Prize for outstanding achievement in planetary science from the American Astronomical Society, based in Washington DC.

What was it about Cosmos that sparked your interest in science?

Listening to Sagan telling stories about how science is done and how scientists work, and describing the thrill of scientific discovery, I said to myself, “That's what I want to do.”

You did a master's degree in genetics. How did you move from that to Martian environments?

It was the other way around. I've been very interested in planetary science and astrobiology since I was a teenager, but there were no university programmes in the field in Spain at the time. Genetics was a distant second interest to me, but I needed to graduate to start my PhD and begin working as a planetary scientist. Astrobiology was starting to become respectable, and I thought that a background in genetics would be appropriate for an astrobiologist interested in Martian environments.

What are your plans for the future?

I'm leaving the SETI Institute because 'soft money' — working solely off grants — is no longer an option for me. When you have a family, you need some kind of stability. I've been offered two academic positions in the United States, and I've won a starting grant from the European Research Council. If I accept one of the offers here, I will stay in US Mars science, which is very attractive right now, especially after the success with the Curiosity rover landing. If I go back to Europe, I will have substantial funding to launch my own group, which seems the logical next step.

Describe your biggest career milestone.

Carbonates are minerals produced in water; the fact that none had been found on Mars had long been used to argue that there were never oceans on Mars. But my adviser told me about a river in Spain that was very acidic; I knew that carbonates do not form in acidic water. I was two years into my PhD and proposed that oceans on Mars were also acidic and that this acidity inhibited the formation of carbonates. A team including me and my adviser submitted a paper on the subject to Nature on 7 January 2004. NASA's rover Opportunity landed on Mars days later — and found direct evidence for such acidic environments. We had accurately anticipated the rover's results. Our paper was published on 23 September 2004, and was central to the completion of my PhD.

Does the Urey prize have a special meaning for you?

It won't help me to get grants or positions, but it is a high personal honour. There is a long list of names of very, very, very important people in planetary science who have won this award.

Has it been difficult to adjust to living and working in the United States?

Not really. Life in California is not so different from life in Spain, and I already had a good command of English. The biggest difference is that the United States rewards effort and merit.

Do you have any regrets about your career?

No. Some time ago I realized that my errors were necessary to bring me to where I am now. I didn't begin to pursue my PhD until I was 30, and while I was away from science I worked as a bartender, a taxi driver, a film-rating classifier and a teacher, among other things. But I got my PhD in 2006 and started working for NASA, and that was a turning point in my career. It offered me the freedom and resources to pursue my own investigations. My career would have been totally different without the NASA experience.