But there could be niches where life thrived in the distant past, when Mars had a thicker atmosphere and a wetter surface. So when Red Planet scientist Janice Bishop was invited to look at carbonate rocks in the Mojave Desert a few years ago, she immediately saw implications for Mars.
Bishop had already published a 2006 International Journal of Astrobiology paper calling iron oxides an "ultraviolet sunscreen" for ancient photosynthesis on Earth. The result of the newer study, published in 2011 in the same journal showed that the Mojave rocks collected also had iron oxide coatings, under which carbonates were hiding.
"They were all hiding under this red mineral at the top, called hematite," Bishop told Seeker in an interview. Hematite is also a common element on Mars.
Besides being senior research scientist and chair of the astrobiology group at the SETI Institute, Bishop is known for her work creating an instrument on the Mars Reconnaissance Orbiter called CRISM (Compact Reconnaissance Imaging Spectrometer). The spacecraft has been taking high-resolution pictures and spectroscopic images of Mars for more than a decade, providing reams of information on how the surface looks like today and how it may have evolved.
And Bishop is one of several scientists working on the "sunscreen" idea. The University of Maryland's Gozen Ertem, for example, is looking at how well biomolecules can hide from ultraviolet radiation in different mixtures. She will present on her research at the American Association for the Advancement of Science Conference next month. (Ertem did not respond to requests for an interview.)
It's unclear how well Martian microbes (if they existed) would have fared in their environment, but at the least the studies on iron oxides are yielding valuable information about how life evolved on Earth. This could help scientists better understand the possibility of life in other environments across the solar system, or even exoplanetary systems.
|Banded iron formations (such as the one pictured at ceter at Karijini National Park, Western Australia) may come in part from iron metabolized by microorganisms|
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