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Project Progress

Development of Life Detection Methodology and Technology (dm)

This project has become one of the major activities of the Astrobiology Program at JPL/Caltech, with many members of the JPL laboratory being involved in the definition of non-earthcentric biosignatures and in the development of methods to measure these biosignatures. It is closely connected to the conceptual issue of the co-evolution of Earth and life on one hand, and the search for life outside the Earth on the other. The program consists of four parts: 1) the definition of life and its biosignatures; 2) the development of methods for measurement of these biosignatures; 3) the fabrication of instruments and software to enable these measurements in the field and eventually in flight, and 4) the use of extreme environments on Earth as terrestrial analogs of life â?? both for testing our life detection methods, and for learning more about the limits of life that should be considered. Finally, there is a genomics component to the work, as one of the major organisms of interest has now been completely sequenced, and genome expression and analysis has become possible. This latter program is jointly funded by NAI and the DOE microbial program.

In the definition of life, we have published two articles on the subject of non-Earthcentric life detection, defining the elements that should be measured, and delineating a preliminary strategy for the measurements. In addition, an internal document describing this strategy and how it can be applied to missions is under preparation.

With regard to the development of methods for measurements, two major projects have emerged. One of these involves the development of UV laser induced fluorescence methods for the detection of organic carbon signatures, while the other involves the development of a desk-top computerized tomographic X-ray unit for the detection of life within endolithic environments. This approach has been very successful as well, with current resolution of endolithic populations now possible at the few micrometer level.

With regard to instrument fabrication, the UV fluorescence apparatus is now to the size of a backpack unit, while the CT instrumentation is a small desk-top unit, soon to be made smaller. In both cases considerable software development has been necessary to adapt the instruments to their new scientific roles. Finally, the work in extreme environments has yielded a range of results, ranging from the isolation of several new extremophilic micro-organisms to the genome sequencing and analysis (both molecular analysis and expression analysis) of Shewanella oneidensis MR-1. This work has revealed that major metabolic innovation in MR-1 has occurred by gene duplication and adaptation with the organism, and has begun to reveal the major modes of regulation under aerobic and anaerobic conditions.