WE PROPOSE TO ADVANCE A CRYOBOT DESIGN THAT USES CLOSED-CYCLE HOT WATER DRILLING (CCHWD) TECHNOLOGY AS THE PRIMARY MEANS OF PENETRATING ICE. THE PRIMARY ROLE OF THE PROMETHEUS (NUCLEAR-POWERED ROBOTIC MECHANISM TECHNOLOGY FOR HOT-WATER EXPLORATION OF UNDER-ICE SPACE) VEHICLE WILL BE TO ENABLE ACTIVELY CONTROLLED DESCENT THROUGH THE ICE SHELL INTO EUROPA S SUBSURFACE OCEAN. IN PROMETHEUS WE WILL DESIGN DEVELOP AND TEST A CCHWD CRYOBOT THAT IS COMPATIBLE WITH A SMALL FISSION REACTOR AND WHICH CAN BE DEVELOPED BY 2022 INTO A REALISTIC FLIGHT CRYOBOT. THE DESIGN IS A NUCLEAR FISSION POWERED SUCCESSOR TO STONE AEROSPACE S VALKYRIE AND SPINDLE CRYOBOTS CAPABLE OF ACHIEVING A 15 KM DESCENT THROUGH A EUROPAN ICE PROFILE IN UNDER A YEAR AND UNDER 200 KG VEHICLE MASS NOT COUNTING REACTOR MASS. BASED ON ANALYSES AND DESIGN WORK FROM PRIOR AND ON-GOING STONE AEROSPACE CRYOBOT PROJECTS WE ANTICIPATE THE FLIGHT CRYOBOT TO HAVE A 37 CM DIAMETER AND 4 M LENGTH.DESIGN ISSUES WE WILL ADDRESS INCLUDE: CREATING AND USING A NUCLEAR SURROGATE HEAT SOURCE FOR REALISTIC TESTING CRYOBOT SUBSYSTEMS OPTIMIZING AN END-TO-END SYSTEM DESIGN TAILORED TO THE EUROPAN ICE COLUMN DESIGNING AN EFFECTIVE HEAT EXCHANGER TO USE REACTOR WASTE HEAT FOR HOT WATER DRILLING DEVELOPING A ROBUST JET PUMP DESIGN FOR WATER JETTING INCORPORATING A PASSIVE MELTING DEFAULT CAPABILITY IN THE EVENT OF CCHWD FAILURE DESIGNING AN EFFICIENT HEAT MANAGEMENT SYSTEM FOR THE VEHICLE VALIDATING THERMAL ANALYSES IN EUROPAN CONDITIONS DEVELOPING AN ONBOARD SPOOLER FOR VERTICAL MOTION CONTROL OF THE CRYOBOT DESIGN AND TESTING OF A PRESSURE SHELL THAT WILL ENABLE CCHWD INITIATION AT THE SURFACE DESIGN AND TESTING OF A NOSE GEOMETRY OPTIMIZED FOR PASSIVE MELTING AT THE SURFACE INVESTIGATION OF DIRTY ICE PROPERTIES AND CRYOVAC TESTING OF CRYOBOT CAPABILITIES WITHIN DIRTY ICE WE WILL TEST A FUNCTIONAL SUB-SCALE CCHWD CRYOBOT AND VARIOUS PROMETHEUS SUBSYSTEMS BOTH IN PURE WATER ICE AND DIRTY ICE IN THE STONE AEROSPACE EUROPA TOWER CRYOGENIC/VACUUM FACILITY. THE INTERNAL VOLUME OF THE EUROPA TOWER CRYOVAC CHAMBER IS 0.75 M IN DIAMETER AND 2 M TALL AND THE CHAMBER CAN SIMULATE THE TEMPERATURES AND VACUUM CONDITIONS BELIEVED TO EXIST IN EUROPA S SURFACE BRITTLE AND DUCTILE ICES.