MODELING OF THE NANOMETRIC REGIME OF CONE-JETS TO IMPROVE THE DESIGN AND UNDERSTANDING OF ELECTROSPRAY THRUSTERS THIS PROJECT WILL REPRODUCE THE ELECTROHYDRODYNAMIC PHENOMENA TAKING PLACE IN ELECTROSPRAY THRUSTERS BY CONSTRUCTING AND NUMERICALLY SOLVING A MODEL OF CONE-JETS WITH REALISTIC BOUNDARY CONDITIONS. THE ULTIMATE GOAL IS TO PRODUCE A MODELING TOOL FOR GUIDING THE DESIGN AND OPTIMIZING THE OPERATION OF ELECTROSPRAY THRUSTERS. THE KEY INNOVATION IS THE INCLUSION FOR THE FIRST TIME OF NOVEL PHYSICS DRIVING THE OPERATION OF THE NANOMETRIC REGIME. IN PARTICULAR THE MODEL WILL INCLUDE: A) THE EQUATIONS OF THE LEAKY DIELECTRIC MODEL (I.E. CONSERVATION OF MASS MOMENTUM AND SURFACE CHARGE; LAPLACE EQUATION FOR THE ELECTROSTATIC POTENTIAL; AND THE YOUNG- LAPLACE EQUATION FOR THE POSITION OF THE FREE SURFACE); B) A NOVEL TERM IN THE CHARGE CONSERVATION EQUATION TO MODEL ION EVAPORATION; AND C) A NOVEL ENERGY CONSERVATION EQUATION TO REPRODUCE THE NON-HOMOGENEOUS TEMPERATURE FIELD CAUSED BY ENERGY DISSIPATION. PROPELLANT PROPERTIES WILL RETAIN THEIR DEPENDENCE ON TEMPERATURE. THE DIRECT OUTCOMES OF THE MODEL ARE THE DEPENDENCE OF THE BEAM CURRENT ION/DROPLET CURRENT FRACTIONS JET DIAMETER DROPLET CHARGE TO MASS RATIO AND PRESSURE JUMP ACROSS THE LIQUID SURFACE ON THE PHYSICAL PROPERTIES OF THE PROPELLANT THE FLOW RATE THE GEOMETRY OF THE ELECTRODES AND THE EMITTER TEMPERATURE. MODEL RESULTS WILL BE VALIDATED WITH EXPERIMENTAL MEASUREMENTS OF RELEVANT ELECTROSPRAY CHARACTERISTICS. THE INTEREST IN SMALLSATS HAS EXPLODED IN THE LAST TWO DECADES DUE TO ADVANCEMENTS IN ELECTRONICS POWER AND FABRICATION TECHNIQUES COMBINED WITH THE SIGNIFICANT LOWER MISSION COSTS ASSOCIATED WITH THE FABRICATION AND LAUNCH OF THESE PLATFORMS AS SECONDARY PAYLOADS. HOWEVER THE CURRENT ABSENCE OF ADVANCED MICROPROPULSION IS PREVENTING THE USE OF SMALLSATS IN MISSIONS OF HIGH VALUE TO NASA SUCH AS SPACECRAFT CONSTELLATIONS FORMATION FLYING INSERTION INTO HIGH ALTITUDE ORBITS INTERPLANETARY VOYAGE ETC. THE MINIMUM THRUST AND POWER AT WHICH ELECTROSPRAY PROPULSION CAN OPERATE ITS HIGH EFFICIENCY THE SMALL FOOTPRINT PER EMITTER AND THE EASINESS FOR SCALE UP MAKE ELECTROSPRAY PROPULSION A TECHNOLOGY IDEAL FOR PRIMARY PROPULSION AND ATTITUDE CONTROL OF CUBESATS AND LARGER SMALLSATS. CONVENTIONAL ELECTRIC PROPULSION TECHNOLOGIES BASED ON A PLASMA DISCHARGE (E.G. ION ENGINES AND HALL THRUSTERS) ARE DIFFICULT TO MINIATURIZE BELOW POWER LEVELS OF TENS OF WATTS DUE TO INCREASING LOSSES AT DECREASING PLASMA DISCHARGE VOLUME AND ARE LIKELY UNSUITABLE FOR THESE PLATFORMS WITH HIGHLY RESTRICTED VOLUME MASS AND POWER BUDGETS. ELECTROSPRAY PROPULSION IS THUS AN ENABLING TECHNOLOGY FOR SMALLSATS AND A FUNDAMENTAL KNOWLEDGE OF HOW IT OPERATES IS NEEDED TO FULFILL ITS POTENTIAL. UNDERSTANDING HOW TO INCREASE THE CHARGE TO MASS RATIO OF ELECTROSPRAYED DROPLETS WHILE SUPPRESSING ION EVAPORATION AND THEREFORE DEVELOPING THE CAPABILITY TO INCREASE THE ISP WILL BE A MAYOR IMPROVEMENT AT THE SYSTEM LEVEL DERIVED FROM THIS PROJECT. CURRENTLY THE ISP OF ELECTROSPRAY THRUSTERS OPERATING IN THE DROPLET AND DROPLET/ION MIXED REGIME IS A FEW HUNDRED SECONDS A RELATIVELY LOW VALUE THAT LIMITS ITS USE FOR HYPOTHETICAL SMALLSAT MISSIONS REQUIRING HIGH DELTA-V (E.G. INTERPLANETARY FLIGHT AND TRANSFER TO HIGH ALTITUDE ORBITS). A SECOND IMPROVEMENT WILL BE LAYING THE FOUNDATION FOR A PASSIVE FEED SYSTEM IN WHICH THE PROPELLANT FLOWS THROUGH THE INNER CHANNEL OF A CAPILLARY TUBE TOWARDS THE EMITTER TIP PULLED BY THE NEGATIVE PRESSURE IN THE TAYLOR CONE EXERTED BY THE ELECTRIC FIELD. A THIRD IMPROVEMENT IS OBTAINING A GOOD UNDERSTANDING OF OPERATION AT VARYING EMITTER TEMPERATURE A COMMON OCCURRENCE DUE TO THE CHANGING ENVIRONMENTAL CONDITIONS TYPICAL OF SPACE MISSIONS.