Life in Martian rocks
If you have read Deception Point by Dan Brown (author of The DaVinci Code) you will get the feel for how much importance is put on finding extraterrestrial life, not as alien civilizations but rather in organic form : bacteria, fossils, microbes, anything which would tell us that other planets can or once could support life. But how do the real life investigations compare with those of fiction? In fact, the race is definitely on and scientific eyes have been turned to Mars for some time now. There is some evidence that Mars was wet and warm in its first hundred million years or so. This could have provided a suitable environment for organic life. However, so far years of study have failed to come up with conclusive evidence. Undaunted, scientists have turned to ever more sophisticated tools to achieve their goal. This month two scientific breakthroughs have could bring us closer to the answer about whether there ever was life on Mars.
The first report is based on studies of minerals since these survive longer than organic matter. Fabien Stalport and his researchers at the University of Paris have turned their attention to calcite formation. On Earth calcite is formed in three different ways: 1. Living organisms create biotic calcite, a good example being limestone. 2. geologic processes such as magmatism can form abiotic calcite. 3. A combination of the two processes can act directly on existing rocks to produce so-called diagenetic calcite. The researchers studied different samples of the three types of calcite and found that while abiotic calcites were pure, the biotic ones contained impurities; their crystals grew faster randomly substituting magnesium atoms for calcium. This created structurally weaker crystals, a fact which became apparent when heat was applied. The biotic samples started degrading at a temperature 40oC cooler than the abiotic ones. The simplicity of this technique means that the appropriate instruments can be included on the future space probes allowing tests to be carried out directly on Mars as to what form of calcites can be found there.
The second report comes from J. William Schopf and and his colleagues at the UCLA. This group has used confocal laser scanning microscopy and Raman spectroscopy to study 650-million to 850-million-year-old fossils preserved in rocks. In the journal Astrobiology this month they showed stunning 3D-images of the fossils. The technique allows them to study microscopic fossils inside the rocks, and search for signs of life, such as organic cell walls. The researchers are confident that, given an opportunity, they could use this technique to analyze material brought from Mars.
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