Astrobiologists are calling on NASA to use what geologists are learning about a new era sometimes called the “Anthropocene” to help develop space missions for the search for extraterrestrial intelligence.
The Anthropocene, although not yet officially recognised as a geological era, reflects the time when humans began influencing the Earth strongly enough to leave significant traces in the geological record. These include everything from ecological changes to planet-wide deposits of radioactive fallout from nuclear bomb tests. There are also materials such as plastics, concrete, and exotic minerals that are likely to find their way into the geological record.
“We are in an era now where human influence is not just starting to affect the climate, but enacting permanent changes that will be visible in the rock record for millions of years,” says Jacob Haqq-Misra, an astrobiologist at the Blue Marble Space Institute of Science, in Seattle, Washington, US.
Not that astronomers can peer into the rock strata of alien worlds in the hope of finding traces of existing (or vanished) civilisations. What they can do is look for changes in planetary atmospheres — changes that Haqq-Misra and colleagues refer to as “techno-signatures” in a policy paper submitted to the US National Academy of Sciences.
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