The latest buzz in the search for life away from our own small blue planet comes from new observations made by the Cassini probe as it orbited one of Saturn’s moons, Enceladus. The observations were made in 2015, but a paper which came out in Science now reveals that Cassini detected hydrogen gas in a plume of material from the moon’s surface, and suggests that Enceladus has active hydrothermal activity on its surface.
The presence of H2 suggests that liquid water below the ice is reacting with rocks. This is important because we know that life on Earth can survive in exactly those conditions. Although the most familiar forms of life on Earth for many people are oxygen-loving, theories suggest that life on Earth may have originated in deep sea vents, feeding on minerals found there. This suggests that the same could occur elsewhere — and Enceladus looks like an excellent candidate.
Even though life in these conditions on Enceladus probably wouldn’t be advanced multicellular life, it’s an important proof of concept. So far, we have no undisputed evidence of life developing anywhere but on Earth. Those who hope for aliens will welcome proof of even simple microbes forming elsewhere — after all, it’s how we all had our beginning!