Lessons Learned from the Mars Relay Network: Considerations for Future Relay Networks

The Mars Relay Network (MRN) has successfully demonstrated how a communications network at another planet can be assembled from dissimilar spacecraft over many years to provide relay services to smaller Mars surface missions. Consisting of Mars orbiters from NASA and ESA, NASA's Mars surface missions, NASA's Deep Space Network (DSN), ESA's deep space tracking network (ESTRACK), and the various operations centers that manage each of these elements (among other entities), this highly successful example of an inter-agency collaboration is a case study in how relay networks at other locations around the solar system could be instantiated.As exploratory interests in other planetary bodies (such as at the Moon or at Venus) continue to increase, the likelihood of needing to implement a relay network at those locations similarly increases. Though much study has been done on the link budgets, communications protocols, and overall network architectures between the various nodes in such networks, many of the lessons learned from the MRN are instead related to managing operations challenges.This paper outlines specific solutions that have been developed to manage the challenges that have arisen from the heterogeneous nature of the MRN, interfacing missions with different spacecraft designs, data handling architectures, operations paradigms, and institutional cultures. The adoption of data exchange standards has been instrumental in ensuring interoperability between the spacecraft and between their human operators. On this latter point, the critical role of the Mars Relay Operations Service (MaROS), which provides a centralized database and platform for mission operators to schedule and coordinate relay opportunities within this node-limited network, is summarized.This paper also describes the ongoing challenges of the ever-evolving MRN as it continues to provide relay services to the Mars surface missions and prepares to provide support for future Mars missions. Finally, this paper makes some recommendations regarding how future, similar networks may improve upon what has been achieved by the MRN.