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Meteorites, Microfossils and ExobiologyThe discovery of evidence for biogenic activity and possible microfossils in a Martian meteorite may have initiated a paradigm shift regarding the existence of extraterrestrial microbial life. Terrestrial extremophiles that live in deep granite and hydrothermal vents and nanofossils in volcanic tuffs have altered the premise that microbial life and microfossils are inconsistent with volcanic activity and igneous rocks. Evidence for biogenic activity and microfossils in meteorites can no longer be dismissed solely because the meteoritic rock matrix is not sedimentary. Meteorite impact-ejection and comets provide mechanisms for planetary cross-contamination of biogenic chemicals, microfossils, and living microorganisms. Hence, previously dismissed evidence for complex indigenous biochemicals and possible microfossils in carbonaceous chondrites must be re-examined. Many similar, unidentifiable, biological-like microstructures have been found in different carbonaceous chondrites and the prevailing terrestrial contaminant model is considered suspect. This paper reports the discovery of microfossils indigenous to the Murchison meteorite. These forms were found in-situ in freshly broken, interior surfaces of the meteorite. Environmental Scanning Electron Microscope (ESEM) and optical microscopy images indicate that a population of different biological-like forms are represented. Energy Dispersive Spectroscopy reveals these forms have high carbon content overlaying an elemental distribution similar to the matrix. Efforts at identification with terrestrial microfossils and microorganisms were negative. Some forms strongly resemble bodies previously isolated in the Orgueil meteorite and considered microfossils by prior researchers. The Murchison forms are interpreted to represent an indigenous population of the preserved and altered carbonized remains (microfossils) of microorganisms that lived in the parent body of this meteorite at diverse times during the past 4.5 billion years (Gy).
Document ID
19980021283
Document Type
Technical Memorandum (TM)
External Source(s)
Authors
Hoover, Richard B. (NASA Marshall Space Flight Center Huntsville, AL United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1997
Publication Information
Publication: SPIE: The International Society for Optical Engineering
Volume: 3111
ISSN: 0277-786X
Subject Category
Astrophysics
Report/Patent Number
NAS 1.26:207366
NASA/TM-97-207366
Meeting Information
Instruments, Methods, and Missions for the Investigation of Extraterrestrial Microoganisms(San Diego, CA)
Distribution Limits
Public
Copyright
Public Use Permitted.

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