Mars Perseverance rover Image Credit: NASA/JPL-Caltech

Image Credit: NASA/JPL-Caltech

Join us for an online community event featuring Dr. Sarah Johnson, Georgetown University and Dr. Carol Cleland , University of Colorado, Boulder.

Recorded on Wednesday, February 24th

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Exciting new research is attempting to find evidence for either extinct or existing life in the universe.  Previous Mars missions found that liquid water existed on Mars in the distant past, raising the question of whether there might be evidence for extinct life. The Curiosity rover, which landed on Mars in 2012, explored the “habitability” of Mars. It found nutrients and energy sources that microbes could have used and established that Mars indeed had regions that could have been friendly to life in the ancient past. The Perseverance rover, launched in July 2020 and landing on Mars in February 2021, will take the next step by looking for the signs of past life itself. At the same time, other nations are joining the search for life on Mars, and new technologies are paving the way for life detection missions to the far reaches of the solar system. 

What sort of evidence of life are scientists looking for and what methods are they employing?  Are these methods too Earth-centric? What would constitute compelling scientific evidence for an unfamiliar form of life?

Dr. Sarah Johnson

Sarah Johnson

Dr. Sarah Johnson is an Associate Professor of Planetary Science at Georgetown University.  Her research group focuses on detecting biosignatures, or traces of life, and is involved with analyzing data from current spacecraft and devising new techniques for future missions. A former Rhodes Scholar and White House Fellow, she received her Ph.D. from MIT and has worked on NASA’s Spirit, Opportunity, and Curiosity Rovers. She is also a visiting scientist with the Planetary Environments Lab at NASA’s Goddard Space Flight Center and the author of The Sirens of Mars: Searching for Life on Another World, which was a New York Times Editor’s Choice and one of the New York Times 100 Notable Books of 2020. 

Dr. Carol Cleland

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Dr. Carol Cleland is a Professor of Philosophy and Director for the Center for the Study of Origins, University of Colorado, Boulder and affiliated with the NASA Institute for Astrobiology (NAI) and a member of CU’s Center for Astrobiology. Specializing in Philosophy of Science, Dr. Cleland is the author of The Quest for a Universal Theory of Life: Searching for life as we don’t know it (Cambridge University Press, 2019) and co-author (with Mark Bedau) of The Nature of Life: Classical and Contemporary Perspectives from Philosophy and Science (Cambridge University Press, 2010; reprinted in paperback 2018). She has published extensively in both science and philosophy journals.  She is currently working with Robert Hazen on developing a more historically informative taxonomy of mineral species for planetary science (PNAS, 12/20). She is also working on a new book on the role of anomalies in scientific discovery.


This event is free and open to the public – no registration necessary. Questions and answers will follow presentations by the two speakers.

Questions? Please email [email protected]