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SlimeSat (Space Laboratory for Investigations of Microbial Ecophysiology): A Proposal for a New Platform for the Investigation of the Effects of Variable Gravity and Space Radiation on Microbial Ecophysiology.    B.M. Bebout¹, E.D. Fleming¹, A.E. Frisbee¹, L.E. Prufert-Bebout¹, J.C. Rask¹, A.J. Ricco², F. Selch¹, S.P. Worden¹, and Bruce Yost¹. ¹ NASA Ames Research Center, Moffett Field, CA, ²Stanford University, Palo Alto, CA. 

A new small satellite mission is proposed.  SlimeSat would use existing flight-qualified and successfully flown small satellite hardware (the GeneSat platform) with suitable modifications to examine the growth and photosynthetic efficiency of cyanobacteria – key target organisms for development and integration into future in-situ resource utilization and life support systems for oxygen production and/or carbon sequestration.  To the growth and measurement capabilities of the GeneSat platform, we would add the capability to conduct the biological experimentation at different g-levels ranging from 0 to 1g, with main focus on lunar and martian gravitational forces.  Cyanobacteria (blue green algae) are bacteria that perform oxygenic photosynthesis, exactly like higher plants on land.  Pulse-amplitude-modulated (PAM) fluorometry would be used to quantify the efficiency of photosynthesis by determining the proportion of photons captured by chlorophyll that are converted to useful chemical energy (as opposed to being lost as fluorescence).  PAM fluorometry has been in wide use in plant physiology and ecology laboratories around the world for some time.  As an optical technique that requires no moving parts and very little energy, it is ideal for adaptation to flight hardware.  The PAM fluorometer provides information about the general condition of the photosynthetic apparatus, key to the well-being of the photosynthetic organism (cyanobacteria, plants, or algae), and is a very sensitive indicator of stress (desiccation, radiation, etc.) in the organism.