Okay, They’re not Out There. But maybe something is. Any form of extraterrestrial life could shed light on at least some questions.
In that spirit, we learn from ScienceDaily of a newly published guidebook, in th form of a seriesof papers based on finds here on Earth:
Some of the leading experts in the field, including a UC Riverside team of researchers, have written a major series of review papers on the past, present, and future of the search for life on other planets. Published in Astrobiology, the papers represent two years of work by the Nexus for Exoplanet Systems Science (NExSS), a NASA-coordinated research network dedicated to the study of planetary habitability, and by NASA’s Astrobiology Institute.
Scientists have identified more than 3,500 planets around other stars (called exoplanets) and many more will be discovered in the coming decades. Some of these are rocky, Earth-sized planets that are in the habitable zones of their stars, meaning it’s neither too hot nor too cold for liquid water — and possibly life — to exist.
The five papers will serve as a reference for scientists searching for signs of life, called biosignatures, in the data they collect from future telescope observations.
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“We are using Earth to guide our search for life on other planets because it is the only known example we have,” said Timothy Lyons, a distinguished professor of biogeochemistry and director of the Alternative Earths Astrobiology Center. “But Earth actually offers us a great diversity of possibilities. Rather than being constrained to a study of present-day life, we use geological and geochemical analyses to examine the billions of years that life survived, evolved, and thrived on Earth under conditions that are very different than today’s, hence the concept of ‘alternative Earths.'”
Schwieterman’s review outlines the complexities of searching for life on planets that are too far away to visit, including phenomena called false positives and false negatives. “The search for life using biosignatures is not as simple as looking for a single molecule or compound. Atmospheric oxygen, for example, could be a sign of life, but there are many nonbiological ways that oxygen gas could be produced on an exoplanet. Conversely, it is possible that life could exist in the absence of oxygen gas, similar to early life on Earth or portions of the oceans today,” Schwieterman said. “This is one reason temporal biosignatures, which are based on dynamic phenomena such as atmospheric seasonality, might be more robust biosignatures in some circumstances.”Paper. (public access) – Edward W. Schwieterman, Nancy Y. Kiang, Mary N. Parenteau, Chester E. Harman, Shiladitya DasSarma, Theresa M. Fisher, Giada N. Arney, Hilairy E. Hartnett, Christopher T. Reinhard, Stephanie L. Olson, Victoria S. Meadows, Charles S. Cockell, Sara I. Walker, John Lee Grenfell, Siddharth Hegde, Sarah Rugheimer, Renyu Hu, Timothy W. Lyons. Exoplanet Biosignatures: A Review of Remotely Detectable Signs of Life. Astrobiology, 2018; 18 (6): 663 DOI: 10.1089/ast.2017.1729 More.
If this gets really interesting, maybe the appropriate answer to “Are They Out There?” is “Tell them we’ll call back as soon as possible.”
See also: Will a new type of photosynthesis, just discovered, change the hunt for alien life?
From Universe Today: Do icy worlds have enough chemicals to support life?
and
Physicist: It’s good news that aliens likely don’t exist. And a space entrepreneur’s surprising reaction… “Preserve the light of consciousness”? Hmmm. Musk doesn’t seem to agree with Darwinian philosopher Daniel Dennett that consciousness is an evolved illusion or with the panpsychists that everything is conscious.