Lunar comms and nav infrastructure – first data relay orbiter Lunar Pathfinder, operational in 2024, paves the way for full constellation by 2030s

Nelly Offord Harle, Clive Oates, Sophie Bywater, Charles Cranstoun, Jonathan Friend, Gary Lay, Ben Schwarz, Paul Stevens, Bernhard Hufenbach, Francesco Liuicci, Matthew Cosby, Chris Saunders

link:: doi:: 10.2514/6.2021-4132


View Video Presentation: comms and nav infrastructure – first data relay orbiter Lunar Pathfinder, operational in 2024, paves the way for full constellation by 2030s A key to sustainable lunar exploration is access to permanent, low-cost and high performance service infrastructure. Easy access to support services such as communication and navigation will rapidly become essential for lunar missions, for technical and economic reasons. A similar trend has already been observed in the transportation domain in the USA, where 14 CLPS (Commercial Lunar Payload Services) compete regularly to provide transportation to the Moon as a service. To an emerging space nation with a low-budget science mission on the far-side, this infrastructure will be an enabler by removing the need for a relay spacecraft. To a commercial endeavour looking to invest in ISRU (In-Situ Resource Utilization), it will help close the business case for investment and grow the demand. Early 2021, in partnership with the European Space Agency (ESA), Surrey Satellite Technology Ltd (SSTL) started the clock on the development of Lunar Pathfinder, the first data-relay lunar orbiter to commercially offer communication services to missions on the surface and in orbit around the Moon. From 2024 onwards, lunar missions of all types (orbiters, rovers, landers, stationary instruments) will be able to access the service and dramatically enhance the value of their mission by lifting the multiple constraints of transferring data back to Earth. Transmitting Direct to Earth (DTE) presents several limitations that can be lifted by the use of a comms relay infrastructure. DTE relies on direct line of sight, which makes it impossible for far-side missions, and a risk for mobile missions likely to encounter obstructing terrain. It also limits the achievable data-rate and contact time with the often oversubscribed deep space ground stations, therefore constraining the overall volume of data that can be retrieved by the end user. With a store and forward capability, a proximity link, two simultaneous channels in S-band and UHF, Lunar Pathfinder data-relay spacecraft is designed to lift these constraints, allowing longer upload durations at higher data-rates with each of the lunar assets, and bulk-sending data, at high speed, back to an Earth Ground Station, ready for distribution to the end users. In addition to its main mission, Lunar Pathfinder will also carry a hosted payload, an ESA GNSS receiver, with the objective of running a GNSS weak signal detection experiment from lunar orbit, a significant step towards navigation service provision for lunar assets. The decision to proceed with building the Lunar Pathfinder infrastructure and services, in the frame of a commercial partnership between SSTL and ESA, was the result of a successful study phase realized for ESA in collaboration with Goonhilly Earth Station (GES). It was also enabled by NASA’s interest in using the communication services for their own robotic assets. Several customer missions are now actively working with SSTL Lunar (a new brand of SSTL, dedicated to the provision of lunar services) to prepare their communication service package. And we are not stopping there… As lunar missions evolve and move from mainly science and exploration towards in-situ resource utilization and purely commercial endeavours, such as tourism, they will increasingly rely on a lunar infrastructure that can provide permanent, low-cost and high performance key support services. Building upon the Lunar Pathfinder experience and the commercialisation of its services, an SSTL-led consortium, including established telecom operators, as well as space and ground segment integrators, is already working on the next generation infrastructure. With a space segment based on a constellation of data-relay orbiters and strong interoperability requirements with other infrastructure elements such as Gateway, the overall system will integrate into the backbone infrastructure.