WE PROPOSE TO EXAMINE THE SPECTRAL AND PHOTOMETRIC PROPERTIES OF THE MATERIAL EMERGING FROM SATURN'S GEOLOGICALLY ACTIVE MOON ENCELADUS USING DATA OBTAINED BY THE VISUAL AND INFRARED MAPPING SPECTROMETER (VIMS) INSTRUMENT ONBOARD THE CASSINI SPACECRAFT. MORE SPECIFICALLY WE PLAN TO CONDUCT THE FOLLOWING INVESTIGATIONS: I) DETERMINE THE PLUME PARTICLE SIZE DISTRIBUTION IN ORDER TO EVALUATE THE IMPORTANCE OF VARIOUS PARTICLE FORMATION PROCESSES INSIDE ENCELADUS. II) INVESTIGATE THE ICE PARTICLES' STRUCTURES IN ORDER TO CONSTRAIN PARTICLE FORMATION CONDITIONS AND THE TOTAL MASS OF PLUME PARTICLES. III) DEVELOP SPECTROPHOTOMETRIC MODELS THAT SHOULD ENABLE US TO BETTER CHARACTERIZE VARIATIONS IN THE PLUME PARTICLE PROPERTIES IN SPACE AND TIME. SINCE THE TINY ICE GRAINS IN THIS PLUME ARE SAMPLES FROM BENEATH ENCELADUS' SURFACE THIS WORK SHOULD PROVIDE NEW INSIGHTS INTO THE PROCESSES OPERATING IN THE MOON'S INTERIOR. TO ACCOMPLISH THE ABOVE SCIENTIFIC OBJECTIVES WE WILL CONDUCT A COMPREHENSIVE ANALYSIS OF THE OBSERVATIONS OF ENCELADUS' PLUME BY CASSINI'S VISUAL AND INFRARED MAPPING SPECTROMETER (VIMS). THIS WILL INCLUDE DATA ACQUIRED AT CLOSE RANGE THAT PROVIDE SPATIALLY RESOLVED OBSERVATIONS OF MATERIAL EMERGING FROM INDIVIDUAL TIGER STRIPE FRACTURES AS WELL AS LOWER-RESOLUTION MEASUREMENTS THAT COVER A BROADER RANGE OF TIMES OBSERVATION GEOMETRIES AND ORBITAL PHASES. WE WILL COMPARE SPECTRA DERIVED FROM THESE VARIOUS OBSERVATIONS TO MODEL SPECTRA COMPUTED FOR A RANGE OF DIFFERENT GRAIN SIZES TEMPERATURES CRYSTALLINITY ETC. IN ORDER TO CONSTRAIN THOSE PARAMETERS AT DIFFERENT LOCATIONS AND TIMES WITHIN THE PLUME. OUR PREVIOUS EXPERIENCE WORKING WITH VIMS SPECTRA OF ENCELADUS' PLUMES (AS WELL AS ICE PARTICLES IN SATURN'S RINGS) AND MODELLING ICE GRAIN SPECTRA PROVIDE US WITH THE NECESSARY EXPERTISE TO CARRY OUT THIS RESEARCH. SINCE THIS INVESTIGATION WILL IMPROVE OUR UNDERSTANDING OF ENCELADUS' GEOLOGICAL ACTIVITY IT IS DIRECTLY RELEVANT TO THE CASSINI DATA ANALYSIS PROGRAM GOAL "TO ENHANCE THE SCIENTIFIC RETURN OF THE CASSINI MISSION BY BROADENING THE SCIENTIFIC PARTICIPATION IN THE ANALYSIS AND INTERPRETATION OF THE DATA RETURNED BY THE MISSION". THIS WORK WILL ALSO CONSIST OF "SCIENTIFIC INVESTIGATIONS UTILIZING ... DATA OBTAINED BY THE CASSINI MISSION" AND SO IS WELL WITHIN THE PURVIEW OF THE CASSINI DATA ANALYSIS PROGRAM