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A network of small satellites is designed to ferry data from Mars to Earth. The small satellites, or data mules, are assumed to have laser communicators and maintain cycler orbits. The concept exploits the fact that two nearby optical communicators can achieve extremely high data rates and that cycler orbits carry a satellite between Mars and Earth regularly. The use of a network of satellites on phase-shifted cycler orbits ensures that transfers from Mars to Earth happen with regular cadence. The cycler approximations, combinations, and cross-link analysis steps are outlined and shown to produce favorable results achieving petabit-scale transfers approximately yearly with as few as six satellites without significantly impacting regular Deep Space Network operations, for an average data rate that is much better than direct downlink alone. [ABSTRACT FROM AUTHOR]

Optical communications are a key technology enabler to return increasing amounts of data from space exploration platforms such as robotic spacecraft in Earth orbit or across the solar system. However, several challenges have hindered the deployment and utilization of this technology in an operational context, most notably its sensitivity to atmospheric impairments such as cloud coverage. To mitigate this problem, building a network of interconnected and geographically disperse ground stations has been proposed as a possible solution to ensure that, at any point in time, at least one space-to-ground optical link is available to contact the space-based platforms. In this paper, we present a new approach for quantifying the availability of an optical ground network that is both computationally inexpensive and suitable for high-level architectural concept studies. Based on the cloud fraction data set, several approximation methods are used to estimate the probability of having a certain number of space-to-ground links fail due to cloud coverage. They are developed in order to capture increasingly complex atmospheric factors, from sites with independent weather conditions, to stations that are both temporally and spatially correlated. Then, the proposed approximation methods are benchmarked and recommendations on how to utilize and implement them are finally summarized. [ABSTRACT FROM PUBLISHER]

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. • Data mule spacecraft flying on Earth–Mars cycler orbits can be used to enhance the capabilities of the Deep Space Network (DSN). • Earth–Mars cycler orbits computed in a patched-conics model are a good initial guess to compute similar cycler orbits in the ephemeris model. • Low-thrust propulsion can be leveraged to design fuel-optimal cycler trajectories. • The propellant mass required to utilize the Earth–Mars cycler orbits is compatible with ESPA-class satellites (< 500 kg). [ABSTRACT FROM AUTHOR]