1) Thermal Propulsion: Uses an inertpropellant which is heated by a power source like nuclear or electric power anddrives it through a supersonic nozzle to create thrust. It’s specific impulseis high but consumes a lot of fuel.
2) Chemical Propulsion: Powered by the exothermic reactions of the propellant. It isclassified into: SolidPropellant LiquidPropellant HybridPropellant Monopropellant3) Ion Drives: Creates thrust bythe acceleration of ions by electricity. These thrusters have very highspecific impulses and thus requires much less amount of fuel compared tochemical or thermal propulsion systems. But,it doesn’t produce a large amount of thrust and can only be used fororientation purposes.4) Solar Sail: Utilizes theradiation pressure exerted by sunlight on large mirrors to generate thrust. Themain advantage is that it does not use any form of fuel at all but relieslargely on solar power alone.
But, like ion thrusters it produces a low amountof thrust and the low availability of sunlight in Ganymede will pose a problemto this system.5) Thermal Fission: A fission reactor isused to heat a propellant to extremely high temperatures and then passed through a nozzle to createhigh thrust. Uncontrolled fission andother risks of handling the fuel canresult in failure of the mission.•A monopropellant rocket utilizes a single chemicalcompound as its propellant. Here, the energy needed for propulsion is obtainedfrom the exothermic reaction produced by the chemical compound. Hydrazine isthe most commonly used monopropellant. It is used in combination with granularalumina catalyst.
An igniter is not used for triggering the reaction. Instead,the catalyst is mixed with Hydrazine which leads to a highly exothermicreaction which produces a 1000?C gas which is a mixture of nitrogen, hydrogenand ammonia producing the required thrust.Acombination of Ion Drive and chemical thruster can result in much lowerconsumption of fuel thus reducing the mass of the whole spacecraftconsiderably. The Ion Drive can be used for the long travel between Earth andGanymede and the thruster can be used for purposes which can’t be fulfilled bythe drive like sudden changes in trajectory