Positioning and Velocity Performance Levels for a Lunar Lander using a Dedicated Lunar Communication and Navigation System

Abstract

With the Moon becoming the next long-term objective in space for both agencies (ESA, 2021; NASA, 2021) and private actors (NASA, 2020), the number of expected missions to Earth's natural satellite might exceed, already in this decade, the overall number reached in the 1960s-1970s (Euroconsult, 2020).In the past, lunar missions have almost entirely relied on direct-to-Earth (DTE) communications, whilst using ranging radiometric measurements from Earth for navigation. The benefits of a lunar relay infrastructure were already envisaged in the early years of the Apollo missions (Farquhar, 1971) and were also demonstrated by the recent far-side landing of the Chinese Chang'E 4 mission (Gao et al., 2019; the latter focused on relaying telemetry to ground rather than providing an independent orbit determination and navigation solution). The growing trend in the number of missions to the Moon is creating demand for the deployment of a lunar communication and navigation infrastructure to support the international community. This, in turn, can act as a catalyst for additional public and private worldwide cislunar initiatives.

LCNS Positioning of a Lunar Surface Rover Using a DEM Based Altitude Constraint

“…In line with previous works [29,33], the lunar surface rover will be equipped with a LCNS receiver which can be modelled similarly to a space-borne GNSS receiver. Such a receiver is comprised of a radio frequency front-end (RFFE) and digital parts for signal processing.…”

“…As mentioned in previous publications [29,32,33], at least during Phase 2 of the Moonlight navigation roadmap, the navigation service will not be able to serve users in every location all the time. Given the limited number of satellites on the initial LCNS constellation (see Section 3.1), the navigation service will be provided in specific time slots for a specific area of the lunar surface.…”

“…final descent of a lunar lander) based on the predicted availability of the service. This process has been described in details in [29] and [33] and it is used accordingly in this contribution.…”

“…The LCNS transmission antenna pattern is considered symmetric and the off-boresight EIRP is provided in Figure 4. The transmission antenna pattern considered in this publication is based on internal ESA studies and aims to provide an example of a more representative pattern compared to previous publications from the same authors [29,33,35]. It is important to note that the final antenna patterns for LCNS are currently under assessment within the Phase A/B1 studies and are expected to be provide similar (or better) performances.…”

“…The maximum slope encountered is 21.2 degrees while the average slope is 8.2 degrees. The traverse was loaded into the ESA Lunar Navigation Simulator [28,29] to acquire the link data with the LCNS satellites. The simulation environment used in the publication considered also the terrain data provided on the NASA planetary data system (PDS) archive and generated by the lunar orbiter laser altimeter (LOLA) [30].…”