Are we ALONE? We asked the experts

Four specialists in the hunt for extraterrestrial life tell Ezzy Pearson how they're hoping to find aliens

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For centuries, humanity has asked itself whether it is alone in its ability to comprehend and investigate the cosmos, and whether Earth is the sole bastion of life in the Universe or simply a single outpost among billions of inhabited worlds. In the past, the exploration of extraterrestrial life was firmly left to the realm of science fiction, but in recent years the hunt for aliens has become an increasingly focused area of rigorous scientific research – from looking for echoes of Earth's habitats in our neighbouring worlds to searching for signals from distant star systems. We spoke with four of the leading figures involved in the hunt – an astrobiologist, an icy moon explorer, an exoplanet expert and a SETI searcher – to find out why we're closer than ever to finding an answer.

Penny Boston
Pioneers the field of astrobiology at the Ames Research Center

What is astrobiology?

Astrobiology is anything that touches on the quest for understanding whether there are other life forms in the rest of our Universe. It really is an all-encompassing, multidisciplinary area of research, looking at the bodies in our own Solar System for signs of past or present lifeforms, all the way out to the study of exoplanets.

How are you helping in the search for alien life?

I look at extreme life forms here on Earth as a template for other environments. Those that tolerate extreme environmental conditions - high temperatures, being frozen, being trapped in a salt crystal, those that process minerals rather than eating organic carbon made by plants. Other folks have studied some small animals, like tardigrades. Everybody loves a tardigrade - they can tolerate a whole lot.

How does learning about Earth help us find aliens?