2006 Annual Science Report
Virtual Planetary Laboratory (JPL/CalTech) Reporting | JUL 2005 – JUN 2006
Searching for Life on Mars: Interpretation of Remote-Sensing Observations of Methane
Mars long has been considered to be a cold, dead planet. However, recent reports of methane in the Martian atmosphere suggest that methane is being produced at present. Thus there is the question of what as-yet unidentified process on Mars is responsible for the observed methane.
To understand what are the possibilities for Martian sources of methane, VPL Team Member Mark Allen co-organized an NAI Distributed Workshop on Martian methane, held on May 18, 2005, at Ames Research Center and other sites around the world. This workshop was an international interdisciplinary forum to discuss the issues raised by the Martian methane detection. Its organization was a cross-NAI team collaborative effort; co-organizers were Bruce Runnegar (NAI Central), James Lyons (NAI UCLA), and Mike Mumma (NAI Goddard). Arising from this workshop were suggestions for a number of possible sources for the Martian methane that were based on the terrestrial analogue. Subsequent to the workshop, the terrestrial analogue as a basis for planning an exploration strategy at Mars to identify the methane source was further developed for a paper submitted to EOS for publication as a feature article.
The main conclusions of this study were that the measurement of the δ13C value for Martian methane alone would not sufficiently distinguish abiogenic geological from biogenic-related processes. Some additional differentiation might be possible if both δ13C(CH4) and δ2H(CH4) were known simultaneously. The presence of ethane, propane and butane, in addition to methane, distinguishes a geological versus microbial origin for hydrocarbon gases, but cannot distinguish between ancient biogenic (thermogenic) processes and abiogenic sources related to water-rock reactions. Future observations at Mars of species congenerated with methane and the correlation of the atmospheric methane abundance with surface features may provide additional insight regarding the potential methane source.
PROJECT INVESTIGATORS:Mark Allen
RELATED OBJECTIVES:Objective 2.1
Biosignatures to be sought in Solar System materials