Dr. Todd Sauke

December 21, 2006

"Isotopic Spectrometer for Astrobiology"


The overarching goal of this project is to collaborate with NASA personnel to define and carry out experiments to apply tunable diode laser technology to exobiological applications in molecular and isotopic analysis. A Stable Isotope Laser Spectrometer (the SILS instrument) is under development at NASA's Ames Research Center to measure isotopic ratios in gas samples, particularly Carbon-13 to Carbon-12 ratios in carbon dioxide gas. The project aims to explore and develop the applicability of tunable diode lasers for exobiological application on space flight missions to the surface of Mars. Isotopic analysis has proven very revealing in elucidating the nature and history of the biogenic elements on Earth and there are an abundance of important applications for isotopic measurements of biogenic elements on Mars. Martian studies present perhaps the most powerful and fruitful extra-terrestrial opportunity to study the evolution of life. Solid state tunable diode laser technology is inherently miniaturizable, requires little electrical power, and provides an ultra-high resolution, tunable, spectroscopic quality source for molecular and isotopic analysis in the important mid-infrared spectral region. Appropriate experimental protocols must be developed to apply this technology to space-flight and planetary applications of interest to NASA. In our laboratory, isotopic ratio measurements of carbon 13/12 using diode laser spectroscopy have been made with an accuracy of significantly better than 0.1 percent. This accuracy is sufficient for many important applications relevant to planetary, geological, and exobiological research and demonstrates the viability of the technique.

We have developed a bench-top model of a thermoelectrically cooled infrared laser source for spectroscopy and, in this project, we plan to continue the development of the thermoelectrically cooled laser spectroscopy source, improve the speed and efficiency of our instrument, and determine optimum trade-offs between science return and instrument design for a miniaturized version of the instrument. In previous related work, we assembled a versatile suite of prototyping hardware for spectroscopy which enables flexible application to a variety of experimental improvements and upgrades of measurement protocols as experimental conditions require and new ideas permit. We have extensive software libraries for data analysis and display and have gained expertise and experience with the technology and methodology to enable rapid progress on future project goals. The instrument concepts to be developed under this project will provide powerful tools for the investigation into how life developed in our solar system.