THE QUESTION OF WHAT ATMOSPHERIC GASES INDICATE THE PRESENCE OF LIFE BOTH ON SOLAR SYSTEM AND EXOPLANETS IS AN OLD ONE. TO GUIDE NEW RESEARCH WE HAVE TAKEN A DATA-DRIVEN APPROACH EXTENDING BEYOND SIMPLE EXTRAPOLATION FROM TERRESTRIAL BIOCHEMISTRY AND BASED ON OUR COMPILATION OF THREE SEPARATE YET INTERTWINED DATABASES. THE FIRST IS A DATABASE OF ALL MOLECULES THAT ARE VOLATILE AND STABLE AT STANDARD TEMPERATURE AND PRESSURE (SEAGER ET AL. 2016). THE SECOND IS A COLLECTION OF MOLECULES PRODUCED BY LIFE ( NATURAL PRODUCTS ) MANUALLY CURATED FROM AVAILABLE LITERATURE AND PUBLIC DATA REPOSITORIES (PETKOWSKI BAINS SEAGER 2018 IN PRESS). THIS DATABASE CONTAINS GENUINE NATURAL PRODUCTS (NOT DRUG METABOLITES OR SYNTHETIC DERIVATIVES) AND EACH NATURAL PRODUCT IS CONNECTED TO SPECIES FROM WHICH THE PRODUCT WAS ISOLATED. THE THIRD DATABASE IS UNDER CONSTRUCTION AND IS A PROXY FOR HYDROLYTICALLY STABLE CHEMICAL SPACE CREATED BY COMBINATORICS FROM SEED MOLECULES AND FILTERED BY HYDROLYTIC AND THERMODYNAMIC STABILITY CALCULATIONS AND ESTIMATORS. WE NOW HAVE DEVELOPED TECHNOLOGY TO DESCRIBE THE STRUCTURE AND THERMODYNAMICS OF THE CHEMICAL SPACE FROM WHICH A BIOCHEMISTRY IS SELECTED. THIS ALLOWS US TO MAP THE CHEMICAL SPACE OF LIFE ONTO AN EXHAUSTIVE SPACE FROM WHICH BIOCHEMISTRY IS SELECTED AND HENCE IDENTIFY BOTH THE CHEMISTRY THAT LIFE USES AND THE LACUNAE THAT LIFE AVOIDS. BUILDING ON THIS WORK WE PROPOSE TO 1] MINE THE DATABASES BOTH TO FIND NOT YET CONSIDERED POTENTIAL BIOSIGNATURE GASES AND EXPLORE SOME OF THEM AND 2] MAP HOW EARTH LIFE EXPLORES CHEMICAL SPACE BY A FEW CONCRETE EXAMPLES OF CHEMICAL FUNCTIONALITY LIFE AVOIDS. THE GOAL IS TO EXTEND CONCEPTS OF POSSIBLE CHEMICAL EVOLUTION RELEVANT TO THE ORIGIN EVOLUTION AND DISTRIBUTION OF LIFE FOR THE FIRST TOPIC WE CONSIDER EXOPLANETS WITH ATMOSPHERES WITH NO MOLECULAR OXYGEN AND LOW TO MEDIUM HOST STAR ULTRAVIOLET RADIATION. THIS OPENS THE POSSIBILITY FOR GASES TO ACCUMULATE TO DETECTABLE LEVELS EVEN FOR MOLECULES RAPIDLY DESTROYED IN EARTH S ATMOSPHERE THUS EXPANDING THE BIOSIGNATURE GASES WE SHOULD BE AWARE OF. PRELIMINARY WORK SHOWS PHOSPINE ISOPRENE AND HALOCARBONS ARE WORTHY FOR DETAILED EXPLORATION. WE WILL USE EXISTING EXOPLANET ATMOSPHERE CODES EXISTING PHOTOCHEMISTRY CODES AND EXISTING MOLECULAR LINE LISTS OR MOLECULE CROSS SECTIONS OR ESTIMATES. FOR THE SECOND TOPIC WE PROPOSE A RADICAL NEW APPROACH BASED ON EXPLORING HOW LIFE AVOIDS OR RARELY USES CERTAIN SPECIFIC CHEMICAL CLASSES OF MOLECULES AS WELL AS THE MOLECULES IT DOES USE. SOME OF THE EXCLUDED MOLECULAR CLASSES ARE CHEMICALLY FLEXIBLE STABLE AND HAVE WIDE CHEMICAL AND STRUCTURAL FUNCTIONALITY. THIS APPROACH HAS NOT BEEN ATTEMPTED BEFORE; INSTEAD THE COMMUNITY HAS FOCUSED ON A WIDE RANGE OF ISOLATED HYPOTHESES AS TO WHY LIFE DOES USE CERTAIN SPECIFIC CHEMICAL FUNCTIONALITIES (E.G. PEPTIDE BOND PHOSPHATES ETC.). WE HAVE QUANTIFIED OCCURRENCE RATES OF DIFFERENT BONDS MOLECULAR FRAGMENTS AND MOLECULES AMONGST LIFE S PRODUCTS SOLIDIFYING KNOWN YET CHEMICALLY PUZZLING GAPS AMIDST THE VAST DIVERSITY OF THE CHEMISTRY OF LIFE. IN RECENT WORK WE PRESENT A HYPOTHESIS FOR LIFE S NEAR AVOIDANCE OF N-S CONTAINING COMPOUNDS (PETKOWSKI BAINS SEAGER IN PRESS) AND THE PROPOSED WORK IS TO EXPLORE ADDITIONAL CONCRETE EXAMPLES. FOR THIS TOPIC WE USE A CUSTOM CHEMICAL COMBINATORICS CODE A SUITE OF PYTHON TOOLS BOTH CUSTOM-MADE AND EXISTING FOR CHEMOINFORMATICS LITERATURE REVIEW FOR REACTION RATES AND EXPERIMENTS INVOLVING NMR TIME COURSE REACTIVITY ASSAYS. THE SIGNIFICANCE OF THIS WORK IS THAT OUR NEW APPROACH MAY PROVIDE FRESH INSIGHT INTO LIFE S EVOLUTION THROUGH CHEMICAL SPACE AND ITS ORIGIN AND EARLY EVOLUTION AS WELL AS AN INSIGHT TOWARDS POSSIBLE BIOCHEMISTRIES AND BIOSIGNATURES OF NON-EARTH-LIKE LIFE ELSEWHERE .