Optimized Low-Thrust Missions from GTO to Mars

A small spacecraft has three primary methods to get to Mars: by a dedicated launch vehicle, by sharing a ride with another Mars-bound mission, or via rideshare to Earth orbit and making its own way to the Red Planet. The third option may be the most attractive in terms of cost effectiveness and frequency of access, which are the main drawbacks of the first two, respectively. In the past 5 years, over 50 satellites have been launched from U.S. soil en route to geosynchronous orbit and beyond. Many of these launches do not use the full capability of the launch vehicle, leaving an opportunity for a small secondary spacecraft to get a ride to geosynchronous transfer orbit (GTO). Starting from an ESPA-ring rideshare to GTO, a solar-electric propulsion (SEP) powered spacecraft can make its own way to Mars orbit to perform a useful mission. In this paper, we explore the mission design space for small, ESPA-class (200-450 kg) spacecraft transferring from GTO to Mars orbit. This is accomplished by creating tools that jointly optimize low-thrust trajectories and spacecraft subsystems to create feasible mission concepts. An example is given of an Areostationary telecom orbiter that reaches Mars in 2 years with a dry mass of 200 kg.