BELOW ITS ICY CRUST EUROPA CONTAINS MORE WATER WITHIN ITS OCEAN THAN ALL THE SURFACE WATER ON EARTH. ADDITIONALLY THAT ~ 100 KM THICK OCEAN HAS LIKELY LAIN IN CONTACT WITH A SILICATE SEAFLOOR AND WATER-ROCK INTERACTIONS MAY BE SUPPLYING CHEMICALLY-REDUCED SPECIES INTO THE OCEAN. IN PARALLEL SUBDUCTION OF SURFACE ICE SHELL MATERIAL COULD PROVIDE A STEADY FLUX OF OXIDANTS (NOTABLY OXYGEN) FROM ABOVE LEADING TO REDOX REACTIONS THAT COULD PROVIDE THE ENERGY AS WELL AS THE ESSENTIAL CHNOPS FOR CARBON-BASED LIFE. ALL THESE FACTORS MAKE EUROPA ONE OF THE MOST GEOPHYSICALLY CHEMICALLY AND POTENTIALLY BIOLOGICALLY INTERESTING ENVIRONMENTS IN OUR SOLAR SYSTEM AND AS SUCH DRIVES OUR INTEREST TO EXPLORE AND SAMPLE ITS ICE AND OCEAN BELOW. TO REACH EUROPAS OCEAN AN ICE-PROBE MUST BE ABLE TO TRAVEL AND COMMUNICATE THROUGH A LAYER OF ICE OVERLYING THE OCEAN POTENTIALLY SEVERAL KILOMETERS (KMS) THICK THAT VARIES IN ITS PROPERTIES WITH DEPTH. THE UPPERMOST FEW KMS WILL BE RADIALLY FLEXING DUE TO THE FORCES OF JUPITER IO AND GANYMEDE. THIS TIDAL MOTION INDUCES FRACTURING AND FAULTING THAT ANY MEANS OF COMMUNICATION FROM A ROBOT SENDING SIGNALS INTERIOR-TO-SURFACE MUST ENDURE. THE EUROPA STI PROJECT PROPOSED HERE WILL TEST MULTIPLE COMMUNICATION TETHER DESIGNS WITH A GOAL OF BRINGING ONE (OR MORE) TO TRL 4/5 (THROUGH VALIDATION IN A LABORATORY SETTING THAT SIMULATES A RELEVANT ENVIRONMENT) AND WILL EVALUATE THE PERFORMANCE OF MULTIPLE FREE-SPACE COMMUNICATION ARCHITECTURES THAT COULD BE COUPLED WITH OR ALTERNATIVES FOR TETHERS TO A SUBSURFACE PROBE. TASKS INCLUDE: 1) CHARACTERIZE STRENGTH&PERFORMANCE OF MULTIPLE TETHERS AND THEIR DEPLOYMENT (PAYOUT) MECHANISM IN A LABORATORY SETTING THAT SIMULATES EUROPA-LIKE CONDITIONS; 2) MODEL POTENTIAL THERMO-MECHANICAL ENVIRONMENTAL HAZARDS WITHIN EUROPA S ICE SHELL THAT COULD POSE RISKS TO PROBE-LANDER COMMUNICATION; AND 3) EVALUATE SYSTEM PERFORMANCE OF RF ACOUSTIC AND OPTICAL FREE-SPACE COMMUNICATION STRATEGIES IN A VARIETY OF MODELED EUROPA ENVIRONMENTS. A STRATEGIC COMMUNICATION REPORT WILL BE PROVIDED TO NASA AS A FINAL DELIVERABLE. THE TETHERS AND PAYOUT HARDWARE WILL BE SUPPLIED BY WHOI AND WILL BE REPRESENTATIVE OF FIBER-OPTIC AND ELECTRICAL COMMUNICATIONS TETHERS AND PAYOUT MECHANISMS USED IN OCEAN RESEARCH ON EARTH INCLUDING ON A NASA-FUNDED EXPEDITION BENEATH ARCTIC SEA ICE IN 2016. OUR TEAM ALSO BRINGS EXPERTISE IN FREE-SPACE COMMUNICATIONS: RF (JHU-APL) AND SUBMARINE OPTICAL AND ACOUSTIC MODEMS (WHOI).