Week 4 Presentation Thursday, Feb 5, 2009 Orbit Transfer Vehicle Electric Propulsion System: High-Level Analysis and Component Specifications Week 4 Presentation Thursday, Feb 5, 2009 Brad Appel Propulsion Group 1

Electric Propulsion System Analysis Determine a performance range for mission feasibility Choose a thruster for the X1 design Hall thruster BHT-1500 from Busek will satisfy the requirements EP system is in general modular  good for scaling System Property Desired Range Mission Constraint Thrust 90 - 200 mN TOF < 1 year Specific Impulse > 1500 s Reduce IMLEO Power Input < 5 kW Reasonable solar array size Brad Appel Propulsion Group 2

Propulsion System Components Xe Tank Pressure Regulator Mass Flow Controller FVV Hall Thruster Power Processing Unit From Power Distribution Unit X1 OTV Propulsion System Component Breakdown Component Mass [kg] Dimensions [m] Cost [$ US] Power Req. [W] Source Hall thruster BHT-1500 5.7 0.23 x 0.23 x 0.20 (box) 230,000 1,670 Busek PPU Assembly 8.3 0.40 x 0.45 x 0.15 (box) 690,000 -- Xenon Feed System 1.6 (plumbing and valves) Busek (Moog PFCV) Contingency Mass 3.1 Xenon Propellant 85 0.051 m^3 sphere diam = 0.46 m 300 DESC Tank 21 sphere diam = 0.47 m TOTAL 124.7 1,150,300   Brad Appel Propulsion Group 3

Backup Slides: EP Performance Comparison Brad Appel Propulsion Group 4

Backup Slides: EP Performance Comparison Brad Appel Propulsion Group 5

Backup Slides: Fundamental Equations Ideal rocket equation for propellant mass: Specific power of overall spacecraft: Mass of spherical tank: Brad Appel Propulsion Group 6

Backup Slides: Other Information Density Supercritical Xe: 1673 kg/m3 Cost Xe: $ 5.00 / liter* Assumptions for sizing code: Delta V = 8 km/s S/C specific power = 65 W/kg Payload = 250 kg *Source: Defense Energy Support Center – FY 2009 Data Brad Appel Propulsion Group 7