THE ELEMENT PHOSPHORUS (P) IS GENERALLY CLASSIFIED AS A MINOR OR TRACE ELEMENT IN TERRESTRIAL AND EXTRATERRESTRIAL SAMPLES. HOWEVER DESPITE ITS RELATIVE SCARCITY IN THE SOLAR SYSTEM PHOSPHORUS HAS RECEIVED A SIGNIFICANT AMOUNT OF ATTENTION FROM THE COSMOCHEMICAL COMMUNITY DUE BOTH TO ITS ROLE IN CAPTURING TRACE ELEMENTS IN PHOSPHATE MINERAL CRYSTAL LATTICES AND IN THE ASTROBIOLOGICAL IMPLICATIONS OF PHOSPHORUS TO THE DEVELOPMENT OF LIFE ON THE EARTH (E.G. PASEK 2015). DESPITE THE ROLE OF PHOSPHORUS IN COSMOCHEMICAL EVOLUTION SEVERAL FACETS OF PHOSPHORUS COSMOCHEMISTRY REMAIN UNCLEAR INCLUDING 1) THE EXTENT OF VOLATILE FORMS OF PHOSPHORUS PRESENT WITHIN THE EARLY SOLAR SYSTEM INCLUDING THE GAS PHOSPHINE (PH3) 2) THE OXIDATION REACTIONS BETWEEN SIDEROPHILIC (METAL-LOVING) P MINERALS SUCH AS SCHREIBERSITE (FE NI)3P AND SILICATES AND OXIDES TO GIVE PHOSPHATE AND 3) A DETAILED ANALYSIS OF WHY SPECIFIC PHOSPHATE MINERALS ARE MORE COMMON IN METEORITES THAN ON PLANETARY BODIES. WE PROPOSE TO INVESTIGATE THESE KEY ASPECTS OF PHOSPHORUS COSMOCHEMISTRY TO BETTER CONSTRAIN THE PHASES AND FORMS THAT GOVERN THE DISTRIBUTION OF THIS KEY ELEMENT IN OUR SOLAR SYSTEM. THIS OBJECTIVE WILL BE ACCOMPLISHED BY EXPERIMENTAL ANALYSES THAT ARE FED INTO SOLAR SYSTEM AND PLANET CHEMISTRY MODELS.