Saturday, July 31, 2010

A Link To Evidence Of Living Organisms On Mars, Roughly 4 Billion Years Ago


A new article in press of the journal Earth and Planetary Science Letters unveils groundbreaking research on the hydrothermal formation of Clay-Carbonate rocks in the Nili Fossae region of Mars. The findings may provide a link to evidence of living organisms on Mars, roughly 4 billion years ago in the Noachian period.

The paper “Hydrothermal formation of Clay-Carbonate alteration assemblages in the Nili Fossae region of Mars”, by Adrian J. Brown et al, suggests that carbonate bearing rocks found in the Nili Fossae region of Mars are made up of hydrothermally altered ultramafic (perhaps komatiitic) rocks. It also shows that the carbonates at Nili Fossae are not pure Mg-carbonate. Moreover, the study explains that talc is present in close proximity to the carbonate locations - rather than previously suggested saponite - and talc-carbonate alteration of high-Mg precursor rocks has taken place.

Adrian Brown, corresponding author, explains: “We suggest that the associated hydrothermal activity would have provided sufficient energy for biological activity on early Mars at Nili Fossae. Furthermore, in the article we discuss the potential of the Archean volcanics of the East Pilbara region of Western Australia as an analog for the Nochian Nili Fossae on Mars. They indicate that biomarkers or evidence of living organisms, if produced at Nili, could have been preserved, as they have been in the North Pole Dome region of the Pilbara craton.”

“Earth and Planetary Science Letters is delighted to be publishing this exciting new scientific finding, which marks a significant finding in the Nili Fossae region of Mars, highlighting similarities between traces of life on early Earth and early Mars, and suggests a landing site for an exobiology mission to Mars", remarked Tilman Spohn, Editor, Earth and Planetary Sciences."

The Nili Fossae region has one of the largest exposures of clay minerals discovered by the mapping spectrometer (called OMEGA for its French name's acronym) on the European Space Agency's Mars Express orbiter. These minerals have also been mapped in greater detail by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on the Mars Reconnaissance Orbiter (See http://crism.jhuapl.edu/gallery/featuredImage).
Color Image of Nili Fossae Trough
Credit: NASA/JPL-Caltech/Univ. of Arizona 

This image covers an area nearly one kilometer (six-tenths of a mile) wide, at 21.1 degrees north latitude, 74.2 degrees east longitude. North is up. It is a composite of exposures that HiRISE took in the infrared, red and blue portions of the spectrum. Color is enhanced beyond the standard enhancement in HiRISE color images, as this view is excerpted from a special video treatment of the full-frame image. The purple areas are basaltic in composition, including sand-sized material that bounces around in the wind to form dunes. Basalt in the most common type of volcanic rock on the Earth and other terrestrial planets. Orange areas are rich in clays. Clay minerals contain water in their mineral structure and may also preserve organic materials, so there is great interest in studying these deposits to understand past environments that could have supported life. The blue-green patches are outcops of unaltered rocks rich in the mineral pyroxene.

This is a portion of the full-frame color image catalogued as PSP_003086_2015 in the HiRISE collection (See http://hirise.lpl.arizona.edu/PSP_003086_2015). The image was taken at a local Mars time of 3:38 p.m. The scene is illuminated from the west with a solar incidence angle of 62 degrees, thus the sun was about 28 degrees above the horizon. The season on Mars was northern autumn. 

Color Image of Nili Fossae Trough, Candidate MSL Landing Site (PSP_003086_2015)
Color Image of Nili Fossae Trough, Candidate MSL Landing Site
Credit: NASA/JPL/University of Arizona

The Nili Fossae region of Mars is one of the largest exposures of clay minerals discovered by the OMEGA spectrometer on Mars Express and mapped in greater detail by the CRISM spectrometer on MRO (see the gallery).

In the HiRISE IRB color, dark blue regions are basaltic in composition, including sand-sized material that bounces around in the wind to form dunes. Basalt in the most common type of volcanic rock on the Earth and other terrestrial planets.

The light-toned areas (with a variety of colors) and covered by small-scale fractures is the clay-rich material. Clay minerals contain hydrogen and oxygen (i.e., water) within their mineral structure, and may also preserve organic materials, so there is great interest in studying these deposits to understand past environments that could have supported life.

NASA also released a video produced by the digital animation group at JPL, scrolling from south to north over this image, as a simulation of the view from the MRO spacecraft.The colors have been specially enhanced for this video, beyond the standard enhancements applied to all HiRISE color images. A sample of the enhanced color is shown here; the purple areas are basaltic materials, orange areas are rich in clays, and the blue-green patches are outcops of unaltered rocks rich in the mineral pyroxene. This would be a wonderful place for detailed exploration by a rover like MSL.

Since its first appearance in 1966, Earth and Planetary Science Letters has built up an enviable reputation. Its successful formula of presenting high-quality research articles with minimal delay has made it one of the most important sources of information in its field. The articles published reflect the great impact made on research in the geosciences by the use of successful research methods from other disciplines such as chemistry, physics, and mathematics. It also covers research into all aspects of lunar studies, plate tectonics, ocean floor spreading, and continental drift, as well as basic studies of the physical, chemical and mechanical properties of the Earth's crust and mantle, the atmosphere and the hydrosphere.

Mid 2002 a new section of short reviews called Frontiers was introduced within Earth and Planetary Science Letters. These high profile papers are written by leading experts and published as the opening pages to regular EPSL issues. The papers fill an important niche of fast communications that bring the scientific community up-to-speed on interesting new areas of science.

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Sources and contacts
NASAAlfred McEwen

Full bibliographic information:The article title is “Hydrothermal formation of Clay-Carbonate alteration assemblages in the Nili Fossae region of Mars” (doi:10.1016/j.epsl.2010.06.018) by Adrian J. Brown and Janice Bishop (SETI Institute), Simon J. Hook, Alice M. Baldridge and Nathan T. Bridges (Jet Propulsion Laboratory), Bradley J. Thomson (Johns Hopkins University Applied Physics Laboratory), Giles M. Marion (Desert Research Institute), and Carlos R. de Souza Filho (Universidade Estadual de Campinas), and James K. Crowley.

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