An Earth-Mars microsatellite mission leveraging low-energy capture and low-thrust propulsion

Growing interest in deep-space exploration using microsatellites is leading the development of novel trajectory design techniques compatible with the constraints of this class of spacecraft. The mission design discussed in this paper examines the possibility of injecting a microsatellite into a desired orbit around Mars taking advantage of multibody dynamics, performing Earth and Moon flybys, which concludes in a low-energy capture at Mars, followed by nonlinear control for orbit injection maneuvers. If compared to a traditional Earth-Mars transfer, the proposed solution leads to relevant propellant savings and extended launch windows, but the capture orbit established has chaotic behavior and time-varying osculating orbital parameters which may not satisfy the mission requirements. Consequently, the microsatellite is capable of transferring from the original low-energy capture orbit to the desired operative one. For this phase, the microsatellite is assumed to operate using a low-thrust propulsion system, which is ignited with the intent of driving the microsatellite toward two operational orbits: (a) a quasi-synchronous repeating 2-SOL orbit and (b) a sun-synchronous orbit with altitude of 200 km. To do this, nonlinear orbit control is employed. Convergence toward the desired operational orbits is investigated, and can be guaranteed - using the Lyapunov stability theory, in conjunction with the LaSalle invariance principle - under certain conditions related to the orbit perturbing accelerations and the low-thrust magnitude. The numerical simulations prove that the combination of multiple-flyby transfer (simulated with real ephemeris, with the use of GMAT) and low-thrust nonlinear orbit control represents a viable and effective strategy for microsatellite missions to Mars.