We present a method for designing and optimizing Earth–Mars cycler orbits for the Solar System Pony Express (SSPE) mission concept. The SSPE is aimed at augmenting the capabilities of the Deep Space Network (DSN) by enabling high latency and high bandwidth communications through the use of interplanetary data mules. The SSPE will leverage a network of smallsats, outfitted with optical laser communications, and by exploiting cycler orbits it will perform flybys of Mars at least once a year, retrieving 1–3 petabits of data per flyby from missions already operating at the planet. This data will then be downlinked to Earth during the next Earth flyby, also occurring about once a year. The SSPE satellites are launched as a rideshare payload with another Mars-bound mission. Each data mule flying in the SSPE network is equipped with a low-thrust propulsion system that is used for cycler orbit injection and for targeting flybys of Earth and Mars. Cycler orbits are first computed using a patched conic approximation and impulsive thrust. These candidate solutions are then transitioned into a higher-fidelity ephemeris model, and using an indirect optimization method, fuel-optimal low-thrust transfers are computed between each pair of flybys. We present three high-fidelity candidate solutions where a 500 kg data mule is inserted into an Earth–Mars cycler orbit using the NASA Evolutionary Xenon Thruster (NEXT). In all three cases, the results show that the fuel consumption is feasible from a mission design perspective and that solutions obtained in the patched conics model can be successfully transitioned to the ephemeris model using low-thrust propulsion.

我们提出了一种为太阳系小马快递 (SSPE) 任务概念设计和优化地球-火星循环器轨道的方法。SSPE 旨在通过使用星际数据骡实现高延迟和高带宽通信，从而增强深空网络 (DSN) 的能力。SSPE 将利用配备光学激光通信的小型卫星网络，并通过利用循环器轨道，每年至少飞越火星一次，从已经在火星上运行的任务中每次飞越获取 1-3 PB 的数据。然后，在下一次地球飞越期间，这些数据将被下行传输到地球，大约每年发生一次。SSPE 卫星与另一项火星任务一起作为拼车有效载荷发射。在 SSPE 网络中飞行的每个数据骡都配备了一个低推力推进系统，用于循环轨道注入和瞄准地球和火星的飞越。首先使用修补的圆锥近似和脉冲推力计算 Cycler 轨道。然后将这些候选解决方案转换为更高保真度的星历模型，并使用间接优化方法计算每对飞越之间的燃料最佳低推力转移。我们提出了三个高保真候选解决方案，其中使用 NASA 进化氙气推进器 (NEXT) 将 500 千克数据骡插入地球-火星循环器轨道。在这三种情况下，