How do you design a mission using electric propulsion for orbit raising?

Electric propulsion orbit raising trades longer transfer time for propellant mass savings. Design considerations: Transfer strategy - Spiral trajectory with continuous thrusting, Optimization of thrust direction and coast arcs, Passage through Van Allen belts (radiation exposure). Analysis: Low-thrust trajectory optimization (indirect or direct methods), Propellant mass vs time vs array degradation trade, and Eclipses during transfer affect thrusting time. System sizing: Thruster power determines thrust (P = T*v/2eta), Solar array sized for end-of-transfer power at 1 AU, Battery for eclipse operations, and Propellant (typically xenon) tank sizing. Mission phases: Launch to GTO on chemical vehicle, Electric propulsion spiral to GEO (4-6 months typical), and Station-keeping thereafter. Benefits: 20-30% mass saving vs chemical insertion, Enables heavier payloads on given launcher. Challenges: Revenue delay, radiation hardening, and extended operations burden.