Lunar Relativistic Positioning System (LRPS) for human exploration

• Main Authors: LEVRINO, LUCA, COLANGELO, LUIGI, GATTO, GIACOMO, LINTY, NICOLA UMBERTO, TARTAGLIA, Angelo, Hoffman, Jeffrey A.
• Other Authors: Sandau R., Nakasuka S., Kawashima R., Sellers J. J., Levrino, Luca, Colangelo, Luigi, Gatto, Giacomo, Linty, NICOLA UMBERTO, Tartaglia, Angelo
• Format: Book Part
• Language: English
• Published: International Academy of Astrunautics 2015
• Subjects: relativistic positioning system; lunar exploration; GNSS; RPS; South Pole; South pole
• Online Access: http://hdl.handle.net/11583/2643719; https://shop.iaaweb.org/?q=node/8870

Abstract: The future of human spaceflight is oriented towards the exploration of planetary bodies beyond Low Earth Orbit (LEO). As on the Earth, the need for a navigation system becomes paramount, especially when we plan to build permanent planetary bases. In particular, this paper treats the case of a human outpost located at the lunar South Pole, and leverages a relativistic positioning algorithm in order to fulfill this goal. This mission is also intended as a test bed for similar future missions. Here, it is shown that it is possible to position users such as manned or unmanned rovers thanks to a constellation of 6 and then 12 nanosatellites orbiting around the Moon, with an accuracy of at most 100 m and 50 m respectively. In fact, the chosen highly elliptical frozen orbits provide coverage over an area centered at the South Pole and of 1500 km radius with at least 4 satellites always in view, which is the minimum number for our positioning algorithm to work. Each satellite is equipped with a clock so that it can emit pulse-like signals that are received by the user, which is equipped with another clock and so it is able to count the pulses emitted by the different nanosatellites. A ground station at the South Pole updates the ephemerides and the proper times of the satellites, transmitting them periodically to the users. In this paper we analyze the architecture of such a mission, describing in details the concept of operations, orbits, and nanosatellites subsystems, maximizing the use of components off the shelf. We also include an implementation plan and a cost model, highlighting the sustainability of the project. Finally, a set of ground tests to qualify this mission for lunar orbit is described, and its top five technical and programmatic risks are discussed.