In case you missed them, here’s a few new stories I’ve published. Thanks as usual to all my excellent editors.

To find aliens, we must think of life as we don’t know it

Artist’s impression of a planet orbiting in the TRAPPIST-1 system. (Image credit: ESO/M. Kornmesser.)

From blob-like jellyfish to rock-like lichens, our planet teems with such diversity of life that it is difficult to recognise some organisms as even being alive. That complexity hints at the challenge of searching for life as we don’t know it – the alien biology that might have taken hold on other planets, where conditions could be unlike anything we’ve seen before. ‘The Universe is a really big place. Chances are, if we can imagine it, it’s probably out there on a planet somewhere,’ said Morgan Cable, an astrochemist at the Jet Propulsion Laboratory in Pasadena, California. ‘The question is, will we be able to find it?’

For decades, astronomers have come at that question by confining their search to organisms broadly similar to the ones here. In 1976, NASA’s Viking landers examined soil samples on Mars, and tried to animate them using the kind of organic nutrients that Earth microbes like, with inconclusive results. Later this year, the European Space Agency’s ExoMars Trace Gas Orbiter will begin scoping out methane in the Martian atmosphere, which could be produced by Earth-like bacterial life. NASA’s Mars 2020 rover will likewise scan for carbon-based compounds from possible past or present Mars organisms.

But the environment on Mars isn’t much like that on Earth, and the exoplanets that astronomers are finding around other stars are stranger still – many of them quite unlike anything in our solar system. For that reason, it’s important to broaden the search for life. We need to open our minds to genuinely alien kinds of biological, chemical, geological and physical processes. ‘Everybody looks for “biosignatures”, but they’re meaningless because we don’t have any other examples of biology,’ said the chemist Lee Cronin at the University of Glasgow…

[Read the entire piece on Aeon, published on 19 September.]

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