1. Propulsion Trade Study for Translational Motion Main ThrustersIsp (s)FuelCatalystOxidizerPower ReqThrust rangeExample Flight HistoryComplexity solid rocket 270 to 290HTPB---38-51 kN Star-37FM (TE-M- 783)extensivesimple cryogenic biprop 445- 465LH 2 -LO 2 - 20,800- 24,750 lbs Pratt&Whitney RL- 10limitedcomplex storable biprop 280- 325 N 2 H 4, MMHIrN2O4N2O4 -2 - 900 lbsHiPAT Dual Modeextensivemoderate monoprop rocket 220- 235N2H4N2H4 Ir--0.5 - 400 NMR-104Bextensivesimple Ion engine3100Xe--2kW20 - 92 mNDS-1limitedcomplex Hall thrusters2000Xe--1.5-4.5kW.025 -.05 N UM-USAF P5 Hall Thrusterlimitedcomplex Electrothermal (arcjet)600N2H4N2H4 Ir-1.8-2.0kW~0.25 Nextensivecomplex Electrothermal (resistojet)300N2H4N2H4 Ir-500-700kW~0.27Non Surrey UoSAT-12extensivecomplex * Hydroxy-terminated Polybutadiene (HTPB) *Liquid hydrogen (LH2) *Liquid oxygen (LO2) *Hydrazine (N2H4) *Xenon (Xe) *Nitrogen Tetroxide(N2O4)

2. Propulsion Options for Attitude Control Attitude ControlAdjustmentTranslationPower Req.3-Dir Rot.Rapid ∆Dir Combine Rot/Trans Professional's Opinion (Steve Lee) momentum wheelvery finenoneyes no yes, with main thrust probably would use a reaction wheel instead reaction wheelvery finenoneyes no yes, with main thrust overkill for this application, usually used for photos monoprop clustersfine-roughyesnoyes yes, off modulationgreat idea!

3. Pressure Regulated vs. Blowdown Tank Pressurization ComparisonPressure RegulatedBlowdown Component ComplexityComplexSimple Controls ComplexitySimpleComplex Pressure lossNoneFunction of propellant consumed Loss in thruster forceNoneFunction of tank pressure MassAdditional mass from presurant monitoring components Additional mass from added tank thickness to withstand high pressures Pressurization RequiredLow  313 psiHigh  745 psi to complete mission #tanks neededOnePotentially two if not enough fuel volume available in high pressure tank Change in performance between ΔV and Attitude maneuvers NoneIsentropic expansion of pressurant results in temperature drop within the tank  temporary lull in pressure. Fits mission profileYesNo