01 / Contract Profile

80NSSC23K0895 Federal Contract Award

Agency code 8000

SOLAR EXTREME ULTRAVIOLET (EUV) AND X-RAY PHOTONS ARE A PRIMARY SOURCE OF ENERGY FOR THE UPPER ATMOSPHERES OF TERRESTRIAL PLANETS. TO BEST CHARACTERIZE HOW THE SOLAR EUV FLUX IMPACTS EARTH S IONOSPHERE-THERMOSPHERE- MESOSPHERE SYSTEM, MORE ACCURATE MODELS OF THE SOLAR EUV SPECTRUM ARE NEEDED. SIMPLE F10.7-BASED PROXY MODELS ARE OFTEN USED, BUT STUDIES HAVE SHOWN THAT MODELS USING FOUR PROXIES FROM DISTINCT TEMPERATURE REGIONS OF THE SUN BETTER ESTIMATE THE SOLAR EUV. MEANWHILE, PHOTOELECTRONS ARE A PRODUCT OF SOLAR EUV PHOTOIONIZING THE NEUTRAL ATMOSPHERE, WHOSE ENERGY SPECTRA PRESERVE DISTINCTIVE FEATURES OF THE SOLAR EUV SPECTRA AND CAN BE USED TO VALIDATE SOLAR IRRADIANCE MODELS. IN THIS PROJECT, WE UTILIZE A UNIQUE COMBINATION OF OBSERVATIONS AND MODELS AVAILABLE AT MARS, THE QUALITY OF WHICH ARE UNPARALLELED BY MEASUREMENTS AT ANY OTHER PLANET INCLUDING EARTH, TO BEST VALIDATE THE SOLAR IRRADIANCE MODELING FOR BOTH MARS AND EARTH, WHICH ADDRESSES FST#1: BEYOND F10.7: QUANTIFYING SOLAR EUV FLUX AND ITS IMPACT ON THE IMT SYSTEM. OUR PROPOSED OBJECTIVES ARE: (1) CHARACTERIZE AND VALIDATE A SOLAR IRRADIANCE MODEL, SYNTHETIC REFERENCE SPECTRA (SYNREF) MODEL, USING A COMBINATION OF MAVEN (MARS ATMOSPHERE AND VOLATILE EVOLUTION) OBSERVATIONS AND PHOTOELECTRON MODELING WITH THE SUPERTHERAML ELECTRON TRANSPORT (STET) MODEL (2) COMPARE VALIDATED SYNREF IRRADIANCES WITH THOSE MEASURED BY THE TIMED AND SORCE X-RAY PHOTOMETER SYSTEM (XPS) LEVEL 4 MODELED IRRADIANCES (3) DEVELOP A SOFT X-RAY PROXY BASED ON THE AUGER ELECTRON FLUXES (PHOTOELECTRONS PRODUCED BY SOFT X-RAYS < ~2.5 NM) AND (4) PROVIDE A FLARE CATALOG FROM 1999 TO 2006 AND 2014 TO 2022 AT THE VANTAGE POINT OF MARS WITH OBSERVATIONS FROM MARS GLOBAL SURVEYOR (MGS) AND MAVEN. OUR OBJECTIVES OF IMPROVING THE SOLAR IRRADIANCE MODELING DIRECTLY ADDRESS FST #1: BEYOND F10.7: QUANTIFYING SOLAR EUV FLUX AND ITS IMPACT ON THE IMT SYSTEM BY IDENTIFYING NEW AND/OR IMPROVED EUV INDICES FOR DRIVING MODEL PREDICTIONS OF ITM STRUCTURE. IN ADDITION, OUR OBJECTIVES 3 AND 4 PROVIDE A LONG-TERM PROXY FOR SOFT X-RAYS AT AN ADDITIONAL VANTAGE AWAY FROM EARTH. THIS ADDITIONAL CATALOG OF FLARES OBSERVED AT MARS IS OF PARTICULAR INTEREST FOR STUDYING OVER-THE-LIMB AND FAR-SIDE FLARE EFFECTS ON NEAR-SIDE DISK RADIANCE AND RADIATIVE TRANSPORT IN THE SOLAR CORONA, WHICH IMPROVES OUR GENERAL UNDERSTANDING OF THE SOLAR FLARE GENERATION AND THUS ALSO HELPS A BETTER QUANTIFICATION OF SOLAR EUV FLUXES.