DIONE AND HELENE SHARE THE SAME ORBIT AT 6.26 SATURN RADII FROM THE GIANT PLANET INSIDE THE E RING. HELENE IS LOCATED IN THE LEADING LAGRANGIAN POINT L4 OF DIONES ORBIT. WE PROPOSE HERE TO INVESTIGATE DIONE HELENE IN TERM OF ORIGIN FORMATION AND EVOLUTION. SPECIFICALLY THE KEY OBJECTIVES ARE TO RETRIEVE THE PHOTOMETRIC PROPERTIES AND COMPOSITION OF THE MOONS TO ANSWER QUESTIONS SUCH AS: ARE DIONE AND HELENE FORMED FROM THE SAME MATERIAL? DID THEY FORM IN THE SAME REGION OF THE SOLAR SYSTEM? IS ONE SATELLITE OLDER THAN THE OTHER? DID THEY GO THROUGH THE SAME AMOUNT OF SPACE WEATHERING? THE CASE OF DIONE AND HELENE IS NOT UNIQUE: TETHYS ALSO SHARES ITS ORBIT WITH TWO OTHER MOONLETS. WE CHOOSE DIONE AND HELENE BECAUSE OF THE LARGER QUANTITY OF DATA AVAILABLE FOR HELENE COMPARED TO OTHER CO ORBITAL MOONS. THIS STUDY IS A STARTING POINT AND CAN BE REPLICATED FOR THE TETHYS AS WELL. CONCISE STATEMENT OF THE METHODS AND TECHNIQUES PROPOSED WE PROPOSE TO USE THE SYNERGY OF THE CASSINI INSTRUMENTS IN ORDER TO PROVIDE THE MOST COMPLETE COMPOSITIONAL EVALUATION OF DIONE AND HELENE POSSIBLE AND ADVANCE OUR UNDERSTANDING OF HOW EXOGENIC PROCESSES AFFECT THE SURFACE OF THESE SATELLITES. TO ACHIEVE THIS GOAL WE WILL GENERATE COMPOSITE RESOLVED AND UNRESOLVED SPECTRA OF BOTH MOONS TO CONDUCT SPECTRAL MODELING OVER A LARGE WAVELENGTH RANGE FROM THE ULTRAVIOLET TO THE INFRARED. FOUR CASSINI INSTRUMENTS WILL BE USED: UVIS (ULTRAVIOLET IMAGING SPECTROGRAPH) ISS (IMAGING SCIENCE SUBSYSTEM) VIMS (VISUAL AND INFRARED MAPPING SPECTROMETER) AND CIRS (COMPOSITE INFRARED SPECTROMETER). UNTIL NOW MOST INVESTIGATIONS HAVE FOCUSED ONLY ON ONE WAVELENGTH DOMAIN TELLING ONLY PART OF THE STORY. A MULTI WAVELENGTH ANALYSIS WILL ALLOW AN IN DEPTH INVESTIGATION OF THE SURFACES OF THE SATURNIAN SATELLITES AS EACH WAVELENGTH PROBES A DIFFERENT LAYER OF THE SURFACE. THIS WILL ALLOW US TO RETRIEVE COMPLIMENTARY PARAMETERS. SPECIAL ATTENTION WILL BE PAID TO THE SEARCH FOR CORRELATIONS OF BASIC PROPERTIES (ALBEDO SCATTERING PROPERTIES TEXTURE GRAIN SIZE COMPOSITION POROSITY THERMAL PROPERTIES) BETWEEN DIONE AND HELENE. WE WILL FOCUS ON SPECTROSCOPIC ANALYSIS OF UVIS ISS VIMS AND CIRS DATA STARTING WITH THE CREATION OF COMPOSITE SPECTRA OF THE SATELLITES DIONE AND HELENE. WE WILL ACCOUNT FOR DIFFERENCES IN INSTRUMENT RESOLUTION BY NEAREST NEIGHBOR REPLICATION OF THE LOW RESOLUTION OBSERVATIONS TO FILL THE SAME PROJECTION GEOMETRY AS THE HIGH RESOLUTION OBSERVATIONS. WE WILL THEN PERFORM A PHASE CURVE ANALYSIS USING PRIMARILY THE HAPKE MODEL BUT ALSO THE BURATTI AND OR SHKURATOV MODELS FOR COMPARISON. THIS FIRST MODELING STEP WILL PROVIDE INPUT PARAMETERS FOR A SPECTRAL MODELING TO INVESTIGATE THE COMPOSITION. WE WILL LOOK FOR SIGNATURES OF AMMONIA HYDROGEN PEROXIDE AND WATER VAPOR UTILIZING ALMOST THE ENTIRE LIGHT SPECTRUM ACCESSIBLE TO CASSINI. TO GET THE BIG PICTURE WE WILL CONNECT THESE RESULTS WITH WHAT IS KNOWN FROM THE PROPERTIES OF THE E RING AND FROM THE OTHER INNER SATELLITES OF SATURN (MIMAS ENCELADUS TETHYS AND RHEA). UPON THE SUCCESSFUL COMPLETION OF THIS PROJECT THE FUTURE PLAN IS TO REPEAT THIS ANALYSIS FOR TETHYS AND ITS CO ORBITAL MOONS TELESTO AND CALYPSO. STATEMENT OF THE PERCEIVED SIGNIFICANCE OF THE PROPOSED WORK TO THE OBJECTIVES OF THE SOLICITATION AND TO NASA INTERESTS AND PROGRAMS IN GENERAL. THE COMBINATION OF DATA FROM MULTIPLE INSTRUMENTS IS KEY TO INCREASING SCIENTIFIC RETURN FROM THE CASSINI OBSERVATIONS. THIS STUDY WILL ALLOW TO QUICKLY ENHANCED THE SCIENTIFIC RETURN OF CROSS TEAM OBSERVATIONS AND WILL INCREASE OUR UNDERSTANDING OF THE E RING REGION. IN ADDITION IT COULD LEAD TO MAJOR SCIENTIFIC DISCOVERIES SINCE THIS WORK BEING THE FIRST TO ASSOCIATE A SATELLITE AND ITS CO ORBITAL MOON(S) IN THE SAME ANALYSIS.