Not listed NASA HAS A LONGSTANDING INTEREST IN LOOKING FOR LIFE ELSEWHERE IN THE UNIVERSE. TELESCOPES ARE CURRENTLY BEING DESIGNED AND BUILT THAT MWILL BE CAPABLE OF IDENTIFYING THE ATMOSPHERIC CONSTITUENTS OF EARTH-LIKE EXOPLANETS. CONSEQUENTLY IT IS DESIRABLE TO SYSTEMATICALLY EXPLORE POTENTIAL ATMOSPHERIC BIOSIGNATURES IN PREPARATION FOR THESE UPCOMING MISSIONS AND USE KNOWN SOLAR SYSTEM ATMOSPHERES FOR COMPARATIVE PLANETOLOGY. CHEMICAL DISEQUILIBRIUM OR THE COEXISTENCE OF TWO OR MORE LONG-TERM INCOMPATIBLE SPECIES HAS BEEN SUGGESTED AS A METHOD FOR LOOKING FOR LIFE REMOTELY. ALL THE BULK GASES EXCEPT FOR THE INERT GASES IN EARTH S ATMOSPHERE ARE CYCLED BY BIOLOGY AND SO IT IS REASONABLE TO EXPECT EXOPLANET ATMOSPHERES TO BE SIMILARLY PERTURBED AWAY FROM EQUILIBRIUM BY BIOGENIC GAS FLUXES. DISEQUILIBRIUM AS A BIOSIGNATURE IS APPEALING BECAUSE UNLIKE SEARCHING FOR GASES SPECIFIC TO PARTICULAR METABOLISMS SUCH AS MOLECULAR OXYGEN THE CHEMICAL DISEQUILIBRIUM APPROACH MAKES NO ASSUMPTIONS ABOUT THE UNDERLYING BIOCHEMISTRY. DESPITE BEING WIDELY CITED IN THE LITERATURE AS A PLAUSIBLE APPROACH THERE ARE VIRTUALLY NO STUDIES INVESTIGATING THE VIABILITY OF ATMOSPHERIC DISEQUILIBRIUM AS A LIFE DETECTION METRIC. WE PROPOSE A SYSTEMATIC INVESTIGATION OF THE UTILITY OF CHEMICAL DISEQUILIBRIUM AS A BIOSIGNATURE THROUGH 3 TASKS. TASK 1 WILL QUANTIFY THERMODYNAMIC DISEQUILIBRIUM FOR ALL PLANETARY ATMOSPHERES IN THE SOLAR SYSTEM THE EARLY EARTH AND AN ENSEMBLE OF MODELED EXOPLANETS. THIS IS DONE BY CALCULATING THE EQUILIBRIUM ABUNDANCES FOR EACH ATMOSPHERE USING GIBBS FREE ENERGY MINIMIZATION AND THEN CALCULATING THE GIBBS FREE ENERGY DIFFERENCE BETWEEN THE OBSERVED AND EQUILIBRIUM STATE TO QUANTIFY THE DEGREE OF DISEQUILIBRIUM. THE HYPOTHESIS WE ARE TESTING IS WHETHER BIOGENIC FLUXES HAVE A MUCH GREATER EFFECT ON ATMOSPHERIC COMPOSITION (AS MEASURED BY THE GIBBS ENERGY DIFFERENCE) THAN ABIOTIC SOURCES OF DISEQUILIBRIUM SUCH AS PHOTOCHEMISTRY AND GEOLOGICAL ACTIVITY. BY EXAMINING A LARGE ENSEMBLE OF PLANETS WE WILL DETERMINE EMPIRICAL RELATIONSHIPS BETWEEN BIOSPHERES AND ATMOSPHERIC DISEQUILIBRIUM. WE ANTICIPATE A SINGLE-NUMBER METRIC LIKE THE GIBBS FREE ENERGY DIFFERENCE TO BE INSUFFICIENT FOR UNAMBIGUOUSLY DETERMINING WHETHER A PLANET POSSESSES LIFE. EVEN WITHIN OUR OWN SOLAR SYSTEM THERE ARE AMBIGUITIES. PRELIMINARY CALCULATIONS INDICATE THAT THERE IS A LARGE BIOGENIC DISEQUILIBRIUM IN EARTH S ATMOSPHERE BUT THERE IS ALSO A LARGE DISEQUILIBRIUM IN MARS ATMOSPHERE CREATED BY PHOTOCHEMISTRY THE PERSISTENCE OF THIS UNEATEN `FREE LUNCH IS AN ANTIBIOSIGNATURE INDICATING THE ABSENCE OF EXTANT LIFE ON MARS SURFACE. TASK 2 WILL INVESTIGATE HOW THIS DEGENERACY BETWEEN BIOSIGNATURES AND ANTIBIOSIGNATURES MAY BE BROKEN WITH KINETIC DISEQUILIBRIUM METRICS. SPECIFICALLY WE WILL INCLUDE AQUEOUS PHASE REACTIONS IN A KINETIC MODEL TO CALCULATE THE POWER DRIVING DISEQUILIBRIUM ON TERRESTRIAL PLANETS WITH OCEANS. FINALLY TASK 3 WILL EVALUATE THE PRACTICALITY OF DISEQUILIBRIUM METRICS GIVEN NEAR-TERM TELESCOPE TECHNOLOGY. THIS WILL INVOLVE SIMULATING OBSERVATIONS WITH UNCERTAINTIES AND INVERTING THESE OBSERVATIONS TO RETRIEVE ATMOSPHERIC ABUNDANCES WITH SIMULATED UNCERTAINTIES. THESE ABUNDANCES WILL BE USED AS INPUTS INTO OUR DISEQUILIBRIUM METRIC CALCULATIONS TO DETERMINE HOW WELL DISEQUILIBRIUM MAY BE CALCULATED GIVEN IMPRECISE OBSERVATIONS. THESE CONCLUSIONS WILL INFORM NASA MISSIONS BY DETERMINING THE TELESCOPE APERTURES AND INTEGRATION TIMES REQUIRED TO DETECT DISEQUILIBRIUM BIOSIGNATURES. THROUGH THIS WORK WE EXPECT TO ANSWER THE ASTROBIOLOGY QUESTION: TO WHAT EXTENT AND IN WHAT CONTEXTS IS ATMOSPHERIC DISEQUILIBRIUM A RELIABLE METRIC FOR LIFE (OR ITS ABSENCE). WE WILL ALSO DETERMINE THE PRACTICAL UTILITY OF DISEQUILIBRIUM METRICS FOR NEAR-TERM TELESCOPE TECHNOLOGY. BY ANSWERING THESE QUESTIONS THIS PROPOSAL DIRECTLY ADDRESSES THE PLANETARY SCIENCE SOLICITATION OBJECTIVE TO 'ASCERTAIN' THE POTENTIAL FOR LIFE ELSEWHERE. $0 8/28/18 3 NASA HAS A LONGSTANDING INTEREST IN LOOKING FOR LIFE ELSEWHERE IN THE UNIVERSE. TELESCOPES ARE CURRENTLY BEING DESIGNED AND BUILT THAT MWILL BE CAPABLE OF IDENTIFYING THE ATMOSPHERIC CONSTITUENTS OF EARTH-LIKE EXOPLANETS. CONSEQUENTLY, IT IS DESIRABLE TO SYSTEMATICALLY EXPLORE POTENTIAL ATMOSPHERIC BIOSIGNATURES IN PREPARATION FOR THESE UPCOMING MISSIONS AND USE KNOWN SOLAR SYSTEM ATMOSPHERES FOR COMPARATIVE PLANETOLOGY. CHEMICAL DISEQUILIBRIUM, OR THE COEXISTENCE OF TWO OR MORE LONG-TERM INCOMPATIBLE SPECIES, HAS BEEN SUGGESTED AS A METHOD FOR LOOKING FOR LIFE REMOTELY. ALL THE BULK GASES EXCEPT FOR THE INERT GASES IN EARTH S ATMOSPHERE ARE CYCLED BY BIOLOGY, AND SO IT IS REASONABLE TO EXPECT EXOPLANET ATMOSPHERES TO BE SIMILARLY PERTURBED AWAY FROM EQUILIBRIUM BY BIOGENIC GAS FLUXES. DISEQUILIBRIUM AS A BIOSIGNATURE IS APPEALING BECAUSE UNLIKE SEARCHING FOR GASES SPECIFIC TO PARTICULAR METABOLISMS SUCH AS MOLECULAR OXYGEN, THE CHEMICAL DISEQUILIBRIUM APPROACH MAKES NO ASSUMPTIONS ABOUT THE UNDERLYING BIOCHEMISTRY. DESPITE BEING WIDELY CITED IN THE LITERATURE AS A PLAUSIBLE APPROACH, THERE ARE VIRTUALLY NO STUDIES INVESTIGATING THE VIABILITY OF ATMOSPHERIC DISEQUILIBRIUM AS A LIFE DETECTION METRIC. WE PROPOSE A SYSTEMATIC INVESTIGATION OF THE UTILITY OF CHEMICAL DISEQUILIBRIUM AS A BIOSIGNATURE THROUGH 3 TASKS. TASK 1 WILL QUANTIFY THERMODYNAMIC DISEQUILIBRIUM FOR ALL PLANETARY ATMOSPHERES IN THE SOLAR SYSTEM, THE EARLY EARTH, AND AN ENSEMBLE OF MODELED EXOPLANETS. THIS IS DONE BY CALCULATING THE EQUILIBRIUM ABUNDANCES FOR EACH ATMOSPHERE USING GIBBS FREE ENERGY MINIMIZATION, AND THEN CALCULATING THE GIBBS FREE ENERGY DIFFERENCE BETWEEN THE OBSERVED AND EQUILIBRIUM STATE TO QUANTIFY THE DEGREE OF DISEQUILIBRIUM. THE HYPOTHESIS WE ARE TESTING IS WHETHER BIOGENIC FLUXES HAVE A MUCH GREATER EFFECT ON ATMOSPHERIC COMPOSITION (AS MEASURED BY THE GIBBS ENERGY DIFFERENCE) THAN ABIOTIC SOURCES OF DISEQUILIBRIUM SUCH AS PHOTOCHEMISTRY AND GEOLOGICAL ACTIVITY. BY EXAMINING A LARGE ENSEMBLE OF PLANETS WE WILL DETERMINE EMPIRICAL RELATIONSHIPS BETWEEN BIOSPHERES AND ATMOSPHERIC DISEQUILIBRIUM. WE ANTICIPATE A SINGLE-NUMBER METRIC LIKE THE GIBBS FREE ENERGY DIFFERENCE TO BE INSUFFICIENT FOR UNAMBIGUOUSLY DETERMINING WHETHER A PLANET POSSESSES LIFE. EVEN WITHIN OUR OWN SOLAR SYSTEM THERE ARE AMBIGUITIES. PRELIMINARY CALCULATIONS INDICATE THAT THERE IS A LARGE, BIOGENIC DISEQUILIBRIUM IN EARTH S ATMOSPHERE, BUT THERE IS ALSO A LARGE DISEQUILIBRIUM IN MARS ATMOSPHERE CREATED BY PHOTOCHEMISTRY THE PERSISTENCE OF THIS UNEATEN `FREE LUNCH IS AN ANTIBIOSIGNATURE, INDICATING THE ABSENCE OF EXTANT LIFE ON MARS SURFACE. TASK 2 WILL INVESTIGATE HOW THIS DEGENERACY BETWEEN BIOSIGNATURES AND ANTIBIOSIGNATURES MAY BE BROKEN WITH KINETIC DISEQUILIBRIUM METRICS. SPECIFICALLY, WE WILL INCLUDE AQUEOUS PHASE REACTIONS IN A KINETIC MODEL TO CALCULATE THE POWER DRIVING DISEQUILIBRIUM ON TERRESTRIAL PLANETS WITH OCEANS. FINALLY, TASK 3 WILL EVALUATE THE PRACTICALITY OF DISEQUILIBRIUM METRICS GIVEN NEAR-TERM TELESCOPE TECHNOLOGY. THIS WILL INVOLVE SIMULATING OBSERVATIONS WITH UNCERTAINTIES AND INVERTING THESE OBSERVATIONS TO RETRIEVE ATMOSPHERIC ABUNDANCES WITH SIMULATED UNCERTAINTIES. THESE ABUNDANCES WILL BE USED AS INPUTS INTO OUR DISEQUILIBRIUM METRIC CALCULATIONS TO DETERMINE HOW WELL DISEQUILIBRIUM MAY BE CALCULATED GIVEN IMPRECISE OBSERVATIONS. THESE CONCLUSIONS WILL INFORM NASA MISSIONS BY DETERMINING THE TELESCOPE APERTURES AND INTEGRATION TIMES REQUIRED TO DETECT DISEQUILIBRIUM BIOSIGNATURES. THROUGH THIS WORK WE EXPECT TO ANSWER THE ASTROBIOLOGY QUESTION: TO WHAT EXTENT, AND IN WHAT CONTEXTS, IS ATMOSPHERIC DISEQUILIBRIUM A RELIABLE METRIC FOR LIFE (OR ITS ABSENCE). WE WILL ALSO DETERMINE THE PRACTICAL UTILITY OF DISEQUILIBRIUM METRICS FOR NEAR-TERM TELESCOPE TECHNOLOGY. BY ANSWERING THESE QUESTIONS, THIS PROPOSAL DIRECTLY ADDRESSES THE PLANETARY SCIENCE SOLICITATION OBJECTIVE TO 'ASCERTAIN' THE POTENTIAL FOR LIFE ELSEWHERE. Other Administrative Action $0 8/28/18 Not listed NASA HAS A LONGSTANDING INTEREST IN LOOKING FOR LIFE ELSEWHERE IN THE UNIVERSE. TELESCOPES ARE CURRENTLY BEING DESIGNED AND BUILT THAT MWILL BE CAPABLE OF IDENTIFYING THE ATMOSPHERIC CONSTITUENTS OF EARTH-LIKE EXOPLANETS. CONSEQUENTLY IT IS DESIRABLE TO SYSTEMATICALLY EXPLORE POTENTIAL ATMOSPHERIC BIOSIGNATURES IN PREPARATION FOR THESE UPCOMING MISSIONS AND USE KNOWN SOLAR SYSTEM ATMOSPHERES FOR COMPARATIVE PLANETOLOGY. CHEMICAL DISEQUILIBRIUM OR THE COEXISTENCE OF TWO OR MORE LONG-TERM INCOMPATIBLE SPECIES HAS BEEN SUGGESTED AS A METHOD FOR LOOKING FOR LIFE REMOTELY. ALL THE BULK GASES EXCEPT FOR THE INERT GASES IN EARTH S ATMOSPHERE ARE CYCLED BY BIOLOGY AND SO IT IS REASONABLE TO EXPECT EXOPLANET ATMOSPHERES TO BE SIMILARLY PERTURBED AWAY FROM EQUILIBRIUM BY BIOGENIC GAS FLUXES. DISEQUILIBRIUM AS A BIOSIGNATURE IS APPEALING BECAUSE UNLIKE SEARCHING FOR GASES SPECIFIC TO PARTICULAR METABOLISMS SUCH AS MOLECULAR OXYGEN THE CHEMICAL DISEQUILIBRIUM APPROACH MAKES NO ASSUMPTIONS ABOUT THE UNDERLYING BIOCHEMISTRY. DESPITE BEING WIDELY CITED IN THE LITERATURE AS A PLAUSIBLE APPROACH THERE ARE VIRTUALLY NO STUDIES INVESTIGATING THE VIABILITY OF ATMOSPHERIC DISEQUILIBRIUM AS A LIFE DETECTION METRIC. WE PROPOSE A SYSTEMATIC INVESTIGATION OF THE UTILITY OF CHEMICAL DISEQUILIBRIUM AS A BIOSIGNATURE THROUGH 3 TASKS. TASK 1 WILL QUANTIFY THERMODYNAMIC DISEQUILIBRIUM FOR ALL PLANETARY ATMOSPHERES IN THE SOLAR SYSTEM THE EARLY EARTH AND AN ENSEMBLE OF MODELED EXOPLANETS. THIS IS DONE BY CALCULATING THE EQUILIBRIUM ABUNDANCES FOR EACH ATMOSPHERE USING GIBBS FREE ENERGY MINIMIZATION AND THEN CALCULATING THE GIBBS FREE ENERGY DIFFERENCE BETWEEN THE OBSERVED AND EQUILIBRIUM STATE TO QUANTIFY THE DEGREE OF DISEQUILIBRIUM. THE HYPOTHESIS WE ARE TESTING IS WHETHER BIOGENIC FLUXES HAVE A MUCH GREATER EFFECT ON ATMOSPHERIC COMPOSITION (AS MEASURED BY THE GIBBS ENERGY DIFFERENCE) THAN ABIOTIC SOURCES OF DISEQUILIBRIUM SUCH AS PHOTOCHEMISTRY AND GEOLOGICAL ACTIVITY. BY EXAMINING A LARGE ENSEMBLE OF PLANETS WE WILL DETERMINE EMPIRICAL RELATIONSHIPS BETWEEN BIOSPHERES AND ATMOSPHERIC DISEQUILIBRIUM. WE ANTICIPATE A SINGLE-NUMBER METRIC LIKE THE GIBBS FREE ENERGY DIFFERENCE TO BE INSUFFICIENT FOR UNAMBIGUOUSLY DETERMINING WHETHER A PLANET POSSESSES LIFE. EVEN WITHIN OUR OWN SOLAR SYSTEM THERE ARE AMBIGUITIES. PRELIMINARY CALCULATIONS INDICATE THAT THERE IS A LARGE BIOGENIC DISEQUILIBRIUM IN EARTH S ATMOSPHERE BUT THERE IS ALSO A LARGE DISEQUILIBRIUM IN MARS ATMOSPHERE CREATED BY PHOTOCHEMISTRY; THE PERSISTENCE OF THIS UNEATEN `FREE LUNCH IS AN ANTIBIOSIGNATURE INDICATING THE ABSENCE OF EXTANT LIFE ON MARS SURFACE. TASK 2 WILL INVESTIGATE HOW THIS DEGENERACY BETWEEN BIOSIGNATURES AND ANTIBIOSIGNATURES MAY BE BROKEN WITH KINETIC DISEQUILIBRIUM METRICS. SPECIFICALLY WE WILL INCLUDE AQUEOUS PHASE REACTIONS IN A KINETIC MODEL TO CALCULATE THE POWER DRIVING DISEQUILIBRIUM ON TERRESTRIAL PLANETS WITH OCEANS. FINALLY TASK 3 WILL EVALUATE THE PRACTICALITY OF DISEQUILIBRIUM METRICS GIVEN NEAR-TERM TELESCOPE TECHNOLOGY. THIS WILL INVOLVE SIMULATING OBSERVATIONS WITH UNCERTAINTIES AND INVERTING THESE OBSERVATIONS TO RETRIEVE ATMOSPHERIC ABUNDANCES WITH SIMULATED UNCERTAINTIES. THESE ABUNDANCES WILL BE USED AS INPUTS INTO OUR DISEQUILIBRIUM METRIC CALCULATIONS TO DETERMINE HOW WELL DISEQUILIBRIUM MAY BE CALCULATED GIVEN IMPRECISE OBSERVATIONS. THESE CONCLUSIONS WILL INFORM NASA MISSIONS BY DETERMINING THE TELESCOPE APERTURES AND INTEGRATION TIMES REQUIRED TO DETECT DISEQUILIBRIUM BIOSIGNATURES. THROUGH THIS WORK WE EXPECT TO ANSWER THE ASTROBIOLOGY QUESTION: TO WHAT EXTENT AND IN WHAT CONTEXTS IS ATMOSPHERIC DISEQUILIBRIUM A RELIABLE METRIC FOR LIFE (OR ITS ABSENCE). WE WILL ALSO DETERMINE THE PRACTICAL UTILITY OF DISEQUILIBRIUM METRICS FOR NEAR-TERM TELESCOPE TECHNOLOGY. BY ANSWERING THESE QUESTIONS THIS PROPOSAL DIRECTLY ADDRESSES THE PLANETARY SCIENCE SOLICITATION OBJECTIVE TO 'ASCERTAIN' THE POTENTIAL FOR LIFE ELSEWHERE. $45.0k 8/15/17 2 NASA HAS A LONGSTANDING INTEREST IN LOOKING FOR LIFE ELSEWHERE IN THE UNIVERSE. TELESCOPES ARE CURRENTLY BEING DESIGNED AND BUILT THAT MWILL BE CAPABLE OF IDENTIFYING THE ATMOSPHERIC CONSTITUENTS OF EARTH-LIKE EXOPLANETS. CONSEQUENTLY, IT IS DESIRABLE TO SYSTEMATICALLY EXPLORE POTENTIAL ATMOSPHERIC BIOSIGNATURES IN PREPARATION FOR THESE UPCOMING MISSIONS AND USE KNOWN SOLAR SYSTEM ATMOSPHERES FOR COMPARATIVE PLANETOLOGY. CHEMICAL DISEQUILIBRIUM, OR THE COEXISTENCE OF TWO OR MORE LONG-TERM INCOMPATIBLE SPECIES, HAS BEEN SUGGESTED AS A METHOD FOR LOOKING FOR LIFE REMOTELY. ALL THE BULK GASES EXCEPT FOR THE INERT GASES IN EARTH S ATMOSPHERE ARE CYCLED BY BIOLOGY, AND SO IT IS REASONABLE TO EXPECT EXOPLANET ATMOSPHERES TO BE SIMILARLY PERTURBED AWAY FROM EQUILIBRIUM BY BIOGENIC GAS FLUXES. DISEQUILIBRIUM AS A BIOSIGNATURE IS APPEALING BECAUSE UNLIKE SEARCHING FOR GASES SPECIFIC TO PARTICULAR METABOLISMS SUCH AS MOLECULAR OXYGEN, THE CHEMICAL DISEQUILIBRIUM APPROACH MAKES NO ASSUMPTIONS ABOUT THE UNDERLYING BIOCHEMISTRY. DESPITE BEING WIDELY CITED IN THE LITERATURE AS A PLAUSIBLE APPROACH, THERE ARE VIRTUALLY NO STUDIES INVESTIGATING THE VIABILITY OF ATMOSPHERIC DISEQUILIBRIUM AS A LIFE DETECTION METRIC. WE PROPOSE A SYSTEMATIC INVESTIGATION OF THE UTILITY OF CHEMICAL DISEQUILIBRIUM AS A BIOSIGNATURE THROUGH 3 TASKS. TASK 1 WILL QUANTIFY THERMODYNAMIC DISEQUILIBRIUM FOR ALL PLANETARY ATMOSPHERES IN THE SOLAR SYSTEM, THE EARLY EARTH, AND AN ENSEMBLE OF MODELED EXOPLANETS. THIS IS DONE BY CALCULATING THE EQUILIBRIUM ABUNDANCES FOR EACH ATMOSPHERE USING GIBBS FREE ENERGY MINIMIZATION, AND THEN CALCULATING THE GIBBS FREE ENERGY DIFFERENCE BETWEEN THE OBSERVED AND EQUILIBRIUM STATE TO QUANTIFY THE DEGREE OF DISEQUILIBRIUM. THE HYPOTHESIS WE ARE TESTING IS WHETHER BIOGENIC FLUXES HAVE A MUCH GREATER EFFECT ON ATMOSPHERIC COMPOSITION (AS MEASURED BY THE GIBBS ENERGY DIFFERENCE) THAN ABIOTIC SOURCES OF DISEQUILIBRIUM SUCH AS PHOTOCHEMISTRY AND GEOLOGICAL ACTIVITY. BY EXAMINING A LARGE ENSEMBLE OF PLANETS WE WILL DETERMINE EMPIRICAL RELATIONSHIPS BETWEEN BIOSPHERES AND ATMOSPHERIC DISEQUILIBRIUM. WE ANTICIPATE A SINGLE-NUMBER METRIC LIKE THE GIBBS FREE ENERGY DIFFERENCE TO BE INSUFFICIENT FOR UNAMBIGUOUSLY DETERMINING WHETHER A PLANET POSSESSES LIFE. EVEN WITHIN OUR OWN SOLAR SYSTEM THERE ARE AMBIGUITIES. PRELIMINARY CALCULATIONS INDICATE THAT THERE IS A LARGE, BIOGENIC DISEQUILIBRIUM IN EARTH S ATMOSPHERE, BUT THERE IS ALSO A LARGE DISEQUILIBRIUM IN MARS ATMOSPHERE CREATED BY PHOTOCHEMISTRY; THE PERSISTENCE OF THIS UNEATEN `FREE LUNCH IS AN ANTIBIOSIGNATURE, INDICATING THE ABSENCE OF EXTANT LIFE ON MARS SURFACE. TASK 2 WILL INVESTIGATE HOW THIS DEGENERACY BETWEEN BIOSIGNATURES AND ANTIBIOSIGNATURES MAY BE BROKEN WITH KINETIC DISEQUILIBRIUM METRICS. SPECIFICALLY, WE WILL INCLUDE AQUEOUS PHASE REACTIONS IN A KINETIC MODEL TO CALCULATE THE POWER DRIVING DISEQUILIBRIUM ON TERRESTRIAL PLANETS WITH OCEANS. FINALLY, TASK 3 WILL EVALUATE THE PRACTICALITY OF DISEQUILIBRIUM METRICS GIVEN NEAR-TERM TELESCOPE TECHNOLOGY. THIS WILL INVOLVE SIMULATING OBSERVATIONS WITH UNCERTAINTIES AND INVERTING THESE OBSERVATIONS TO RETRIEVE ATMOSPHERIC ABUNDANCES WITH SIMULATED UNCERTAINTIES. THESE ABUNDANCES WILL BE USED AS INPUTS INTO OUR DISEQUILIBRIUM METRIC CALCULATIONS TO DETERMINE HOW WELL DISEQUILIBRIUM MAY BE CALCULATED GIVEN IMPRECISE OBSERVATIONS. THESE CONCLUSIONS WILL INFORM NASA MISSIONS BY DETERMINING THE TELESCOPE APERTURES AND INTEGRATION TIMES REQUIRED TO DETECT DISEQUILIBRIUM BIOSIGNATURES. THROUGH THIS WORK WE EXPECT TO ANSWER THE ASTROBIOLOGY QUESTION: TO WHAT EXTENT, AND IN WHAT CONTEXTS, IS ATMOSPHERIC DISEQUILIBRIUM A RELIABLE METRIC FOR LIFE (OR ITS ABSENCE). WE WILL ALSO DETERMINE THE PRACTICAL UTILITY OF DISEQUILIBRIUM METRICS FOR NEAR-TERM TELESCOPE TECHNOLOGY. BY ANSWERING THESE QUESTIONS, THIS PROPOSAL DIRECTLY ADDRESSES THE PLANETARY SCIENCE SOLICITATION OBJECTIVE TO 'ASCERTAIN' THE POTENTIAL FOR LIFE ELSEWHERE. Funding Only Action $45.0k 8/15/17 1 NASA HAS A LONGSTANDING INTEREST IN LOOKING FOR LIFE ELSEWHERE IN THE UNIVERSE. TELESCOPES ARE CURRENTLY BEING DESIGNED AND BUILT THAT MWILL BE CAPABLE OF IDENTIFYING THE ATMOSPHERIC CONSTITUENTS OF EARTH-LIKE EXOPLANETS. CONSEQUENTLY, IT IS DESIRABLE TO SYSTEMATICALLY EXPLORE POTENTIAL ATMOSPHERIC BIOSIGNATURES IN PREPARATION FOR THESE UPCOMING MISSIONS AND USE KNOWN SOLAR SYSTEM ATMOSPHERES FOR COMPARATIVE PLANETOLOGY. CHEMICAL DISEQUILIBRIUM, OR THE COEXISTENCE OF TWO OR MORE LONG-TERM INCOMPATIBLE SPECIES, HAS BEEN SUGGESTED AS A METHOD FOR LOOKING FOR LIFE REMOTELY. ALL THE BULK GASES EXCEPT FOR THE INERT GASES IN EARTH S ATMOSPHERE ARE CYCLED BY BIOLOGY, AND SO IT IS REASONABLE TO EXPECT EXOPLANET ATMOSPHERES TO BE SIMILARLY PERTURBED AWAY FROM EQUILIBRIUM BY BIOGENIC GAS FLUXES. DISEQUILIBRIUM AS A BIOSIGNATURE IS APPEALING BECAUSE UNLIKE SEARCHING FOR GASES SPECIFIC TO PARTICULAR METABOLISMS SUCH AS MOLECULAR OXYGEN, THE CHEMICAL DISEQUILIBRIUM APPROACH MAKES NO ASSUMPTIONS ABOUT THE UNDERLYING BIOCHEMISTRY. DESPITE BEING WIDELY CITED IN THE LITERATURE AS A PLAUSIBLE APPROACH, THERE ARE VIRTUALLY NO STUDIES INVESTIGATING THE VIABILITY OF ATMOSPHERIC DISEQUILIBRIUM AS A LIFE DETECTION METRIC. WE PROPOSE A SYSTEMATIC INVESTIGATION OF THE UTILITY OF CHEMICAL DISEQUILIBRIUM AS A BIOSIGNATURE THROUGH 3 TASKS. TASK 1 WILL QUANTIFY THERMODYNAMIC DISEQUILIBRIUM FOR ALL PLANETARY ATMOSPHERES IN THE SOLAR SYSTEM, THE EARLY EARTH, AND AN ENSEMBLE OF MODELED EXOPLANETS. THIS IS DONE BY CALCULATING THE EQUILIBRIUM ABUNDANCES FOR EACH ATMOSPHERE USING GIBBS FREE ENERGY MINIMIZATION, AND THEN CALCULATING THE GIBBS FREE ENERGY DIFFERENCE BETWEEN THE OBSERVED AND EQUILIBRIUM STATE TO QUANTIFY THE DEGREE OF DISEQUILIBRIUM. THE HYPOTHESIS WE ARE TESTING IS WHETHER BIOGENIC FLUXES HAVE A MUCH GREATER EFFECT ON ATMOSPHERIC COMPOSITION (AS MEASURED BY THE GIBBS ENERGY DIFFERENCE) THAN ABIOTIC SOURCES OF DISEQUILIBRIUM SUCH AS PHOTOCHEMISTRY AND GEOLOGICAL ACTIVITY. BY EXAMINING A LARGE ENSEMBLE OF PLANETS WE WILL DETERMINE EMPIRICAL RELATIONSHIPS BETWEEN BIOSPHERES AND ATMOSPHERIC DISEQUILIBRIUM. WE ANTICIPATE A SINGLE-NUMBER METRIC LIKE THE GIBBS FREE ENERGY DIFFERENCE TO BE INSUFFICIENT FOR UNAMBIGUOUSLY DETERMINING WHETHER A PLANET POSSESSES LIFE. EVEN WITHIN OUR OWN SOLAR SYSTEM THERE ARE AMBIGUITIES. PRELIMINARY CALCULATIONS INDICATE THAT THERE IS A LARGE, BIOGENIC DISEQUILIBRIUM IN EARTH S ATMOSPHERE, BUT THERE IS ALSO A LARGE DISEQUILIBRIUM IN MARS ATMOSPHERE CREATED BY PHOTOCHEMISTRY; THE PERSISTENCE OF THIS UNEATEN `FREE LUNCH IS AN ANTIBIOSIGNATURE, INDICATING THE ABSENCE OF EXTANT LIFE ON MARS SURFACE. TASK 2 WILL INVESTIGATE HOW THIS DEGENERACY BETWEEN BIOSIGNATURES AND ANTIBIOSIGNATURES MAY BE BROKEN WITH KINETIC DISEQUILIBRIUM METRICS. SPECIFICALLY, WE WILL INCLUDE AQUEOUS PHASE REACTIONS IN A KINETIC MODEL TO CALCULATE THE POWER DRIVING DISEQUILIBRIUM ON TERRESTRIAL PLANETS WITH OCEANS. FINALLY, TASK 3 WILL EVALUATE THE PRACTICALITY OF DISEQUILIBRIUM METRICS GIVEN NEAR-TERM TELESCOPE TECHNOLOGY. THIS WILL INVOLVE SIMULATING OBSERVATIONS WITH UNCERTAINTIES AND INVERTING THESE OBSERVATIONS TO RETRIEVE ATMOSPHERIC ABUNDANCES WITH SIMULATED UNCERTAINTIES. THESE ABUNDANCES WILL BE USED AS INPUTS INTO OUR DISEQUILIBRIUM METRIC CALCULATIONS TO DETERMINE HOW WELL DISEQUILIBRIUM MAY BE CALCULATED GIVEN IMPRECISE OBSERVATIONS. THESE CONCLUSIONS WILL INFORM NASA MISSIONS BY DETERMINING THE TELESCOPE APERTURES AND INTEGRATION TIMES REQUIRED TO DETECT DISEQUILIBRIUM BIOSIGNATURES. THROUGH THIS WORK WE EXPECT TO ANSWER THE ASTROBIOLOGY QUESTION: TO WHAT EXTENT, AND IN WHAT CONTEXTS, IS ATMOSPHERIC DISEQUILIBRIUM A RELIABLE METRIC FOR LIFE (OR ITS ABSENCE). WE WILL ALSO DETERMINE THE PRACTICAL UTILITY OF DISEQUILIBRIUM METRICS FOR NEAR-TERM TELESCOPE TECHNOLOGY. BY ANSWERING THESE QUESTIONS, THIS PROPOSAL DIRECTLY ADDRESSES THE PLANETARY SCIENCE SOLICITATION OBJECTIVE TO 'ASCERTAIN' THE POTENTIAL FOR LIFE ELSEWHERE. Funding Only Action $30.0k 8/18/16