Q&A WITH AN ASTROBIOLOGIST

Scientists have detected the longest organic molecules on Mars to date, a major leap forward in the search for life on the Red Planet

- Anita Chandran talks to Dr Caroline Freissinet

What makes your team's discovery on Mars so exciting?

We found large organic molecules composed of 10, 11 and 12 atoms of carbon. These long, chain-shaped molecules - called alkanes - are very fragile. They're much more fragile than the ring-shaped (or 'aromatic') molecules made of carbon that we detected previously. What this shows is that these long-chain molecules can be preserved over geological periods of time. They were found on rocks that are 3.7 billion years old, which means they were deposited 3.7 billion years ago and preserved until today. This has huge implications for the search for life on Mars, because we believe that, if life ever existed on Mars, it was around the same time that these molecules were deposited.

What do we mean by 'organic' molecules?