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2008 Annual Science Report

Indiana University, Bloomington Reporting  |  JUL 2007 – JUN 2008

Design, Construction and Testing of a Cavity-Ring Down Spectrometer for Determination of the Concentration and Isotopic Composition of Methane

Project Summary

The recent detection of CH4 in the Martian atmosphere and observations suggesting that it varies both temporally and spatially argues for dynamic sources and sinks. CH4 is a gaseous biomarker on Earth that is readily associated with methanogens when its H and C isotopic composition falls within a certain range. It is imperative that a portable instrument be developed that is capable of measuring the C and H isotopic composition of CH4 at levels comparable to that on Mars with a precision similar to that of an isotope ratio mass spectrometer and that such an instrument be space flight capable. Such an instrument could guide a rover to a site on Mars where emission of biogenic gases is occurring and samples could be collected for Mars sample return.

4 Institutions
3 Teams
0 Publications
0 Field Sites
Field Sites

Project Progress

Design, construction and testing of a Cavity-Ring Down Spectrometer (CRDS) for determination of the concentration and isotopic composition of methane

During the past 12 months, we have measured in detail the absorption spectra for 12CH4, 13CH4, CH3D and CO2. We’ve designed a peak fitting routine to integrate the 12CH4 and 13CH4 peaks in the wavelength region of our CRDS. We’ve tested this software on a CH4 gas standard of known isotopic composition and were able to reproduce the δ13C of the 2 ppm standard with an accuracy of ±5o/oo. Although this accuracy is twice that of the multipass instrument on MSL, it is 10 times less than the accuracy of the individual ring-down events. The inaccuracy is due to imprecision in the wavelength of the laser, which will be rectified by upgrading the instrument with a wavelength monitor. A manuscript describing the methodology, instrument and first measurement is being prepared for Optics Express. A proposal to take the current instrument to Technology Readiness Level 6 was submitted to the Mars Instrument Development Program in June ’07 with collaboration from Paul Mahaffy of Goddard Space Flight Center and has recently been awarded.

We also tested a Los Gatos CRDS at the McGill University arctic research station (MARS) on Axel Heiberg Island for two weeks in April ’08 where we measured CH4 fluxes from the permafrost soil and hot springs. These results indicate that the CH4 fluxes are sufficiently high that our current CRDS should be able to measure their isotopic composition and our current plan is to return to MARS next spring with the upgraded instrument. We are presently preparing the instrument for CH4 activity measurements on permafrost methanogens while they are being exposed to simulated Martian conditions at the Techshot facility in Greenfield, Indiana.

    John Kessler
    Project Investigator
    Tullis Onstott Tullis Onstott
    Project Investigator
    Barbara Sherwood Lollar

    Objective 2.1
    Mars exploration

    Objective 2.2
    Outer Solar System exploration

    Objective 3.3
    Origins of energy transduction

    Objective 4.1
    Earth's early biosphere

    Objective 5.1
    Environment-dependent, molecular evolution in microorganisms

    Objective 5.2
    Co-evolution of microbial communities

    Objective 5.3
    Biochemical adaptation to extreme environments

    Objective 6.1
    Environmental changes and the cycling of elements by the biota, communities, and ecosystems

    Objective 6.2
    Adaptation and evolution of life beyond Earth

    Objective 7.1
    Biosignatures to be sought in Solar System materials

    Objective 7.2
    Biosignatures to be sought in nearby planetary systems