Exobiology / Science / Space

A whole new world

Saturn’s icy moon Enceladus, photographed by the Cassini orbiter in 2005.

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!

9 thoughts on “A whole new world

    • Aside from my textbooks, which cover it briefly, yes! In no particular order: I recently read The Vital Question, by Nick Lane. What is Life by Addy Pross sort of touches on that, too, though it’s more generally about how chemical reactions become biological, rather than a specific theory of the origin of life on Earth. Rare Earth by Peter D. Ward also touches on it, and why complex life is probably uncommon in the universe. Ward also has a new book which I haven’t read yet, A New History of Life. Adam Rutherford has a rather fun book, Origin of Life / Creation, which touches both on the origin of life on Earth and synthetic biology.


  1. I thought (and I could absolutely be wrong about this) we had discovered bacteria fossils in meteorites? Or are bacteria not simple microbes? Thanks in advance!


    • That’s more of a controversial theory than something all scientists would agree with, I think. There’s certainly people who believe that those shapes are fossils of bacteria. Oddly enough, I’m having trouble finding anything directly addressing that online. If I find any more information, I’ll make a post about it!

      Bacteria are indeed simple microbes, at least in that they don’t have complex internal structures (though they are highly adapted for a whole range of environments — in fact, it’s recently been found that bacteria thrive better in zero gravity).


      • Yeah, there was a Martian meteorite with structures in that were interpreted by one research group as being fossil bacteria. As far as I understand it, that interpretation is controversial and the structures (whatever they may be) have only been seen in the one meteorite. So not exactly a smoking gun.


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