Earth-Mars microsatellite mission using ballistic capture and low-thrust propulsion

Growing interest in the 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 to inject a microsatellite into a desired orbit around Mars taking advantage of multi-body dynamics, performing a double gravity, from the Moon and the Earth, which concludes in a low-energy capture at Mars, and nonlinear control for orbit injection maneuvers. If compared to a traditional Earth-Mars transfer, the proposed solution allows relevant propellant savings, although limiting the targeting of specific arrival conditions at Mars and of the orbit parameters at the capture. Consequently, the microsatellite shall be capable of performing the maneuvers required to transfer from the original capture orbit to the desired operative one. In this work, the microsatellite is assumed to be equipped with 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 gravity assist transfer (simulated also 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.