Life in the Martian Meteorite - Case Study Example

Institution: Life in the Martian Meteorite ALH84001 Name: Date: Instructor: Life in the Martian Meteorite ALH84001 Table: Evidence for and against the biogenic origin of features in the Martian meteorite For Against 1.Morphological evidence Morphological evidence is described in terms of form and structure. There was evident of tube like structures that were believed to have a close resemblance to fossils. Therefore the tube like structures resembled pieces of fossilized bacteria that had occurred close to the globules. During the exploration process feasible cells were also reported and their sizes ranging from 80-100nm (Bradley et al. 1997). 1.Morphological evidence The morphology of the nanostructures was believed to be very minute such that their survival was not guaranteed in any way possible. Therefore the explanation for the nanostructures can be entirely being attributed to the sides and angles outlook of the finely layered crystal. The little descriptions of the evident of unusual morphologies are incomplete and there was lack of information on internal mechanisms. Hence the explanation was mainly as a result of speculations (Mckay, 2010). 2.Crystallographic evidence There was great evidence of the magnetite that were generated as a result of microbe’s bacterial strain. There was formation of an exclusive crystal that was described in the form of hex octahedral shapes. The crystals were believed to have been formed as a result of inorganic process and the evident of water that assisted in the formation of the crystals. Thus the presence of magnetite crystals in Martian meteorite may be as a result of biogenic process. They were therefore regarded as a form of evidence of oldest life yet to be found (Mckay et al. 1996). 2.Crystallographic evidence There was lack of reports of the presence of inorganic processes that was engaged in the explanation of hexa-octahedral magnetite terrestrial model. Furthermore the presence of bacterial strain may be considered as a product of natural selection. The crystal therefore may be formed as a result of natural selection processes as opposed to the existence of life (Gibson et al. 2001). 3.Mineralogical evidence Carbon globules were believed to have been formed during the time when there was the existence of liquid form of water. Carbonate globules are generally formed in the earth as a result of biologic actions at temperatures below 100 degrees centigrade. It is therefore evident that the carbonate globules existed in low temperatures aqueous basis as they were moderately uninterrupted through succeeding processes. Magnetite substances are comparable to magnet fossils found in sediments and soils (Thomas-Keptra et al. 2001). 3.Mineralogical evidence Carbonate globules can be formed even on earth without the existence of biological manipulation and even at high temperatures as above 650 degrees centigrade. Thus the existence of carbonate globules exhibited no features to imply the likelihood that they were generated by living process within its existence (Gibson et al. 2001). 4.Chemical evidence The materials found involved the evidence of chemical composition for instance hydrocarbons and other minerals composition within the substances. In addition there was presence of complex organic molecules. In these case amino acids the terrestrial contamination process was the likelihood of Martian indigenous. Thus the biological molecules present exhibited the resemblance of PAH’s generated through biological processes on earth (Bradley et al. 1996). 4.Chemical evidence The evidence of the suggestions based on the existence of life has not been acknowledged widely. This is due to the fact that it is believed that the weathering and modification in the process of being exposed to the environmental setting on the ice surface. Meteorites on the surface of the ice are generally warmed by the rays of the sun and therefore melt the adjacent ice thus giving the opportunity and the likelihood of contamination and chemical adjustment (Bradley et al. 1996). 5.Isotopic evidence The isotopic composition evident in the carbonate globules. Hence in this case the Polycyclic aromatic hydrocarbons (PAHs) together with amino acids that are considered to be the chemical structure blocks of proteins were evident and consistent. The original carbon bearing molecules of PAHs were therefore considered as evidence of the existence of life that formed the isotopic component (Becker et.al. 1999). 5.Isotopic evidence On the other hand the isotopic component was considered to be inconsistent with the composition of the molecules. Hence the molecule composition within the carbonate globules were inconsistent and only assumptions were made in regards to the isotopic form of composition (Becker et.al. 1999). Morphological evidence: Morphology can be considered as evidence in form of shapes, forms and structures in existence. Morphology evidence was considered in terms of microscopy metaphors that resembled fossils. The fossils are generally used as evidence of some form of existence with its origin in form of structures and shapes (Weiss et al. 2004). Crystallographic evidence: Crystallography is regarded as the study of crystals. The study of crystals therefore forms the evidence of the existence of crystals in its own form and pattern. Crystal are generally substances that take a arithmetical form as a result of regular collection of molecules. Hence the molecules form the crystal. An example of the evidence based form of crystal involves the hexa-octahedral magnetite. Mineralogical evidence: Minerals are considered as important form of substances. Therefore minerals are essential geological substances comprising of a precise chemical composition. An example of a form of minerals includes CaCo3. This type of mineral constitutes the composition of both carbon and calcium. Calcium and carbon forms the composition of this type of mineral (Knoll, 1998). Chemical evidence: The analysis of minerals is important for the purpose of giving an exact chemical composition of minerals. The evidence founded chemical composition such as hydrocarbons constitute certain chemical components that are evident through microprobe analysis of the composition of the minerals. Isotopic evidence: As isotope evidence is considered as a ration of various elements within a particular substance. The composition of the elements can be in various forms of ratio. For instance the carbonate isotope may be in form of C, H, O, S in various ratios (Becker et al. 1998). Summary Many scientists throughout the world are in the quest of discovering the existence of life in another planet other than the earth. Achieving a generally acknowledged stand in regard to the existence of life in another planet draws a lot of difficulty and arguments. Thus the observations made in relation to the existence of life elicited some forms of alternative types of explanations to the inorganic processes. Despite a lot of alternative form of explanations there was a great evidence of the existence of life on planet Mars in early periods due to the evidence that was observed. The magnetite crystals form the strongest form of evidence of the existence of life. However, the evidence is considered as incidental and therefore elicited a lot of controversies. In this case there is need for dedication in a lot of research to determine the evidence of alien life in other planets as opposed to making numerous types of assumptions. List of References Becker, L., Popp, B., Rust, T., &Bada, J. L,1999,The Origin of Organic Matter in the Martian Meteorite ALH84001.Earth and Planetary Science Letters, Vol. 167, Issues 1-2, pp. 71-79. Bradley, J. P., Harvey, R. P. &McSween Jr., H. Y.,1996, Magnetite Whiskers and Platelets in the ALH84001 Martian Meteorite: Evidence of Vapor Phase Growth. GeochimicaetCosmochimicaActa, Vol. 60, No. 24, pp. 5149-5155. Thomas-Keprta, K. L., Clemett, S. J., Bazylinski, D. A., Kirschvink, J. L., McKay, D. S., Wentworth, S. J., Vali, H., Gibson, Jr., E. K., McKay, M. F. &Romanek, C. S., 2001, Truncated hexa-octahedral magnetite crystals in ALH84001: Presumptive biosignatures. Proceedings of the National Academy of Sciences of the United States of America, Vol. 98, No. 5, pp. 2164-2169. http://www.pnas.org/content/98/5.toc McKay, D. S.,Gibson Jr., E. K., Thomas-Keprta, K. L.,Vali, H., Romanek, C. S., Clemett, S. J.,Chillier, X. D. F., Maechling, C. R. &Zare, R. N., 1996, Search for Past Life on Mars: Possible Relic Biogenic Activity in Martian Meteorite ALH84001. Science, Vol. 273, Issue 5277, pp. 924-928. http://links.jstor.org/sici?sici=0036-8075%2819960816%293%3A273%3A52772.0.CO%3B2-V Weiss, B. P., Kim, S. S., Kirschvink, J. L., Kopp, R. E., Sankaran, M., Kobayashi, A. and Komeili, A., 2004, Magnetic tests of magneto some chains in Martian meteorite ALH84001. Proceedings of the National Academy of Sciences of the United States of America, Vol. 101, No. 22, pp. 8281-8284. http://www.pnas.org/content/101/22.toc McKay, C.P., 2010, Liquid water formation around rocks and meteorites on Antarctic Polar Plateau ice.Antarctic Science, Vol. 22, 287-288. Knoll, Andrew, H., 1998, “A Martian Chronicle”. The Sciences, July/August 1998, pages 20-26. Gibson, Everett K. Jr., McKay, David S., Thomas-Keprta, Kathie L., Wentworth, S. J., Westall, F., Steele, Andrew, Romanek, Christopher S., Bell, M. S., Toporski, J., 2001, “Life on Mars: evaluation of the evidence within Martian meteorites ALH84001, Nakla, and Shergotty”. Precambrian Research, 106, pages 15-34 Read More