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Project Progress

The prime objectives of this effort are to (1) estimate the probable extreme environment constraints for a habitable planet, (2) predict the microbial communities most likely to remain active on a planet across a significant fraction of the planet’s lifespan, for stars of different spectral types, and (3) develop both linear and non-linear statistical methods for detecting spectral signatures resulting from the activity of these communities. Accomplishing these goals requires a combination of modeling, laboratory experimentation, and fieldwork. Efforts this year have been greatly enhanced by collaborations with colleagues in the Ames Research Center (ARC) and Jet Propulsion Laboratory (JPL) Biosignatures (JPL1) teams.

Modeling efforts have included work on principal component analysis of near infrared spectral signatures, studies of the photosynthetic limits of the continuously habitable zone, and a first attempt to describe the feedback loops that may have contributed to stabilization of the Archean biosphere. Laboratory and fieldwork have focused on attempts to determine whether a biosphere can develop in basalt or ultramafic rocks. If microbial communities can ?make a living? in such primordial environments without prior chemical weathering, biogeochemical interaction may appear quite early in the life history of a terrestrial planet.

We plan to extend our work with Martin Fisk and have received a NASA Exobiology award to explore the distribution of microbial life in deep subsurface basalts. We are submitting an Exobiology proposal with Bob Coleman to explore the serpentinization of olivine in the ultramafic formations in The Cedars. We are extending our principal component analysis of spectral signatures into visible spectral regions and adding gas giant spectra to the data set. We will continue our collaboration with David Des Marais to understand the signal detection limits for cyanobacterial mat gas fluxes across the Earth’s history. We will also continue to explore the likelihood of developing significant biospheres on planets orbiting cooler stars than our Sun.