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Project Progress

Astrobiology Funding to the US Geological Survey (dm)

The primary objective of last year’s work was to examine hyperthermophile communities in Yellowstone National Park and tufa deposits in the Mono and Searles Lake Basins to determine whether these different communities exhibited unique spectral signatures in the visible to near-infrared wavelengths (350-2500 nm). We focused the YNP work on Mushroom Spring, Octopus Spring and Nymph Creek. In those areas we found that each of the major communities displays spectral absorptions unique to each community. For example, for Cyanidium caldarium from Nymph Creek, it has a green peak at 542 nm and an otherwise flat visible spectra. The red edge occurs at 710 nm and there is an absorption centered at 878 nm. Downstream, Chlorella-like organisms occur. These organisms have spectral characteristic very different from the Cyanidium-like community at the spring source. Phormidium from Octopus Spring has a complex spectra with visible maxima at 590 and 648 nm, chlorophyll a absorption at 675 nm, and absorptions at 740 (bacteriochlorophyll c), 798, and 874 nm. The in situ spectra show the same absorptions as the extracted Synechococcus-chlorophyll a absorption, red edge at 765 nm and absorptions at 716, 798 and 877 nm. The red color of the Chloroflexus is subdued as it lies below the Synechococcus. These differences are due not only to the various compounds but also the manner in which they occur in the organisms. Differences in the spectral character of sinter were also observed, with sinter around pools having hyperthermophile organisms exhibiting absorptions due to organic compounds. Data for tufa from Mono Lake and Searles Lake show that both thermal emission and visible-near infrared variations in the spectral character of tufa occur, which can be attributed to differences not only in the mineralogy but also to differences in other attributes such as the amount of absorbed water.