The study of possible life on worlds beyond Earth is somewhat complicated by the fact that we have yet to find life on worlds beyond Earth. As a result, astrobiology is primarily focused, not on studying extraterrestrial life, but on developing ways to find it — chemical markers of biological activity we test for in samples taken from Mars or other planets. Recently, CSUN Professor of Biology Chhandak Basu advanced a proposal that one such “biomarker” could be gene expression data, based on profiles of microorganisms found closer to home.
Basu and his coauthor Scott Perl, a scientist with the NASA Jet Propulsion Laboratory and the Los Angeles Natural History Museum, made the case for their approach in the journal Frontiers in Astronomy and Space Sciences this past summer. Astrobiologists already identify possible biomarkers by studying bacteria and other microbes found in extreme environments on Earth that approximate chemical, temperature, and light conditions found on other planets. Basu and Perl suggest that RNA sequencing of such “extremophile” microorganisms would identify markers of the biological processes necessary for survival in those habitats. To the extent that Martian life is based on chemistry similar to that found on Earth, it would likely use similar biological processes. Thus, better understanding of extremeophile gene expression on Earth could help identify biomarkers to test for in Martian samples.
The full paper is available Open Access on the journal website.
Image: Earth, viewed from orbit. (Flickr: NASA)