posted August 22, 1997
|Testing the Evidence for Life on Mars: NASA and NSF Fund New Studies of Martian Meteorite
Written by G. Jeffrey Taylor
Hawai'i Institute of Geophysics and Planetology
NASA and the National Science Foundation (NSF) have awarded grants to test the evidence that fossil life has been discovered in martian meteorite ALH84001. PSR Discoveries has covered the debate about the evidence in a series of articles and will continue to do so.
The projects, funded after close scrutiny by other scientists, are listed below. They are organized by type of investigation and arranged alphabetically in each section. Many of the studies actually address topics across subject areas, but we list them under the topic that constitutes the major portion of the research being done.
The nature of organic compounds is important in evaluating whether life existed on Mars. The presence of organic compounds alone does not prove that life existed, as such chemicals can form by nonbiological processes, too. One of the chief research problems will be to test for contamination of the samples, on both Mars and Earth.
|Amino Acids and Other Organic Compounds in Antarctic Meteorites and Ice (NASA grant)|
|An Investigation of Carbon Isotope Abundances in ALH84001 (NSF grant)|
|Carbon Characterization, Element Abundances and X-ray Near Edge Structure Measurements on ALH84001 (NASA grant)|
|The Search for Unique Biomarkers in the Martian (SNC) Meteorites ALH84001 and EETA79001 (NASA grant)|
Biomarkers are minerals or other substances whose presence indicate that organisms were living in a rock. Many of the investigations focus on the nature of the mineral magnetite in ALH84001, in comparison to magnetite produced by bacteria on Earth.
|Deciphering Sulfur Isotopic Systematics as a Potential Biomarker in ALH84001 (NASA grant)|
|High Resolution Examination of the Intact "Microfossil" - Mineral Interface of ALH84001 for Evidence of Physical and Mineralogical Changes Consistent with Microbial Activity (NSF grant)|
|Iron-Oxide and-Sulfide Mineral Particles as Biomarkers (NSF grant)|
|Microstructural Studies Bearing on the Origin of Carbonates and Associated Minerals in Martian Meteorite ALH84001 (NASA grant)|
|Oxide and Sulfide Mineral Indicators of Past Biological Activity (NASA grant)|
|The Isotopic Composition of Iron: A Chemical Fingerprint for Ancient Life (NASA grant)|
|The Isotopic Composition of Iron: A Chemical Fingerprint for Biologic Activity (NSF grant)|
The possible fossils in ALH84001 are associated with carbonate minerals. There is a raging debate about how the carbonates formed, with some scientists claiming that the carbonates formed at low temperatures, hence consistent with life, while others argue that the carbonates formed at high temperatures (more than 700 oC), incompatible with life. The numerous investigations in this area are designed to determine the temperature and mode for formation of the carbonate minerals in ALH84001.
|An Electron Microscopy Survey of Carbonate-Bearing Regions of ALH84001 (NASA grant)|
|Collaborative Research: Ion Microprobe Analysis of O and C Isotope Ratios in ALH84001 (NSF grants)|
|Experimental Investigations of the Origins of Martian Carbonates (NASA grant)|
|Isotropic and Experimental Constraints on the Genesis of Carbonates in Martian Meteorite ALH84001 (NASA grant)|
|Paleomagnetic and Rock Magnetic Constraints on the Thermal History of Martian Meteorite ALH84001 (NASA grant)|
|Pathways of Mineral Alteration and Organic Synthesis in Hydrothermal Systems on Mars (NSF grant)|
|Petrologic Studies of Martian Carbonates in ALH84001 (NSF grant)|
|Stable Isotopic Analysis of Secondary Minerals in ALH84001 (NASA grant)|
One of the most dramatic lines of evidence is the existence in ALH84001 of fossil-like objects. It is also one of the most controversial lines of evidence. Studies focus on the nature of very tiny fossils and living bacteria in rocks on Earth, for comparison to those in ALH84001.
|Do Nanobacteria Exist? A Microbial Landscape at Nanometer Scale (NASA grant)|
The age of the carbonate minerals is important for understanding the evolution of climate on Mars. It is also indirectly related to the issue of fossil life in ALH84001, as some age estimates suggest that the carbonates formed about 3.5 billion years ago, during the time when the climate of Mars is thought to have been wetter and warmer than it is now. However, determining the age of the carbonates may be the most difficult experiment of all those funded.
|Comprehensive Microprobe Studies of Stable Isotopes, Noble Gas Isotopes and Trance Elements in Primary and Secondary Minerals in Ancient Martian Meteorites (NASA grant)|
|Radiometric Dating of ALH84001 Carbonates (NASA grant)|
One investigation involving numerous scientists from several institutions encompasses all the categories above, in an integrated, multidisciplinary project.
|An Evaluation of Biogenicity in ALH84001 (NASA grant)|
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