SCIENCE GOALS&OBJECTIVES THE GOAL OF THIS PROJECT IS TO UNDERSTAND THE PRESERVATION POTENTIAL OF MOLECULAR BIOSIGNATURES WITHIN LACUSTRINE SEDIMENTS ON EARLY MARS. USING LABORATORY ANALYSES THE PRINCIPAL OBJECTIVE WILL BE TO DETERMINE THE RATES OF DEGRADATION FOR MOLECULAR BIOSIGNATURES IN COLD DRY ENVIRONMENTS USING SEDIMENT SAMPLES OBTAINED FROM LAKE UNTERSEE A CLOSED-BASIN PERENNIALLY ICE-COVERED ANTARCTIC LAKE AND AN ADJACENT PALEO-LAKE BASIN. UNDERSTANDING THE TAPHONOMY OF MOLECULAR BIOSIGNATURES IN COLD DRY ONCE AQUEOUS ENVIRONMENTS IS CRITICAL FOR DEVELOPING STRATEGIES TO SEARCH FOR EVIDENCE OF LIFE ON MARS - WHERE MEAN ANNUAL TEMPERATURES MAY HAVE BEEN WELL BELOW FREEZING EVEN DURING THE PLANET'S PRESUMED WARM AND WET PERIOD - AND ALSO HAS IMPLICATIONS FOR THE SEARCH FOR LIFE ON ICY MOONS. PERENNIALLY ICE-COVERED LAKES ARE RARE ON EARTH AND THEIR COLD AND DRY PALEO-COUNTERPARTS ARE ESPECIALLY FEW. HYPERARID BIOMARKER PRESERVATION FROM SUCH DEPOSITS REMAIN LARGELY UNDERSTUDIED. IN TEMPERATE HYPERARID SOILS LABILE LIPID BIOMARKER STRUCTURES ARE WELL PRESERVED OVER MILLIONS OF YEARS. HOWEVER IT IS STILL NOT KNOWN IF FRAGILE INFORMATION-RICH BIOMOLECULES SUCH AS DNA WOULD SURVIVE OVER GEOLOGICAL TIMESCALES UNDER OPTIMAL CONDITIONS. IN MANY ENVIRONMENTS IT IS OFTEN EXCEEDINGLY DIFFICULT TO KNOW THE DIVERSITY AND ABUNDANCE OF THE SOURCE BIOMASS FOR PRESERVED BIOMARKERS WHICH LEADS TO DIFFICULTY IN MEASURING THE RATE OF DEGRADATION. THESE UNCERTAINTIES CAN BE ADDRESSED BY STUDYING SEDIMENTS FROM THE UNTERSEE OASIS. LOCATED IN QUEEN MAUD LAND ANTARCTICA LAKE UNTERSEE HAS A LOCAL CLIMATE THAT IS DOMINATED BY INTENSE EVAPORATION AND SUBLIMATION. ITS ECOLOGY IS DOMINATED BY PROKARYOTIC MICROORGANISMS THAT FORM BENTHIC MICROBIAL MATS WITH A RANGE OF MORPHOLOGIES INCLUDING PINNACLES AND LARGE CONICAL STRUCTURES. ADJACENT TO LAKE UNTERSEE IS AN ICE-FREE REGION THAT CONTAINS A PALEO-LAKE BASIN. THIS BASIN;AND ITS SHORELINES CONTAIN LACUSTRINE CLAYS AND DESICCATED MICROBIAL MATS THAT ONCE RESIDED BENEATH THE ICE-COVER OF A LAKE THAT REACHED DEPTHS OF 50-60 M. SAMPLES COLLECTED IN 2016 AND NOW AT NASA AMES RESEARCH CENTER RANGE FROM MODERN MICROBIAL MATS TO THOSE THAT HAVE BEEN EXPOSED TO COLD DESICCATION DURING RECENT DECADES TO THOSE THAT HAVE BEEN DESICCATED FOR UP TO 10 000 YEARS. THIS RANGE OF SAMPLE EXPOSURE AGES WILL ALLOW US TO EXPLORE THE EFFECT OF COLD AND DRY TAPHONOMIC PROCESSES ON BIOMARKER DEGRADATION. WHILE THIS IS RELATIVELY BRIEF FROM A GEOLOGICAL PERSPECTIVE IT ALLOWS US TO UNDERSTAND THE EARLY STAGES OF BIOMARKER DIAGENESIS DURING WHICH TIME MOST DEGRADATION OCCURS. HYPOTHESES&MEASUREMENTS WE PROPOSE TO MEASURE THE ABUNDANCE AND STRUCTURAL INTEGRITY OF RANGE OF BIOMOLECULES IN TERMS OF STABILITY: DNA PROTEINS AND LIPIDS. WE HYPOTHESIZE THAT DNA WILL BE SIGNIFICANTLY MORE DEGRADED THAN PROTEINS AND THAT PROTEINS WILL BE PREFERENTIALLY LOST IN COMPARISON TO MORE RECALCITRANT LIPIDS. BY COMPARING THE ABUNDANCE OF THESE BIOMOLECULES IN THE FREEZE-DRIED MATS OF VARIOUS AGES TO THE MODERN MATS IN LAKE UNTERSEE WE CAN MEASURE THE RATE OF DEGRADATION WITH INCREASING EXPOSURE AGE. SIGNIFICANCE AND RELEVANCE WITH THIS PROJECT WE SEEK TO FILL AN IMPORTANT KNOWLEDGE GAP BY INVESTIGATING THE EARLY DIAGENESIS AND THE PRESERVATION POTENTIAL OF MOLECULAR BIOMARKERS IN AN EXCELLENT PLANETARY ANALOG ENVIRONMENT FOUND IN ANTARCTICA. THIS PROJECT RESPONDS TO AND IS RELEVANT TO NASA EXOBIOLOGY THEMES "EARLY EVOLUTION OF LIFE AND THE BIOSPHERE" AND "BIOSIGNATURES AND LIFE ELSEWHERE" KEY RESEARCH QUESTIONS ABOUT BIOSIGNATURES (NASA ASTROBIOLOGY STRATEGY 2015) AND IS DIRECTLY RELEVANT TO GOAL 7 OF THE ASTROBIOLOGY ROAD MAP: DETERMINE HOW TO RECOGNIZE SIGNATURES OF LIFE ON OTHER WORLDS AND ON EARLY EARTH.