Development of a magnetic cardan suspension coupled with a single actuated axis for gravity assisted pointing of directional devices: A case study of Moon to Earth alignment for a laser ranging reflector

A new class of Lunar Laser Ranging (LLR) experiments has been recently investigated by the international Space Agencies, in order to deploy a set of Next Generation Lunar Reflector (NGLR) on the Moon surface, funded under NASA's Commercial Lunar Payload Services (CLPS) program (Currie et al., 2020). In principle the Cube Corner Reflector (CCR) arrays deployed by Apollo and Lunokhod missions in the 70's will be flanked (at different locations) by single bigger reflectors, thus removing the systematic errors in the Time of Flight (TOF) measurement induced by the Moon librations (Turyshev et al., 2012).In this paper we describe a mechanism formed by a passive cardan magnetic suspension, dedicated to the alignment of the CCR toward the mean Earth direction. The suspension is able to compensate for the misalignment due to the slope of the landing site that can be different at each site (Zupp, 2013). If proper control of azimuth angle of the spacecraft at touchdown cannot be guaranteed, an additional motor to rotate the magnetic suspension must be provided by the lander, for the alignment toward the mean Earth direction.Once the landing site is defined, the geometry of the retroreflector housing, together with that of the cardan suspension, will autonomously (without human intervention) and passively (without provision of electrical power by the lander) provide the right elevationThe mechanical performances of the magnetic suspension have been preliminarily investigated in (Ancillai et al., 2020). The solution presented can be applied to any directional device, requiring pointing capability, like antennas, and can be adopted with low friction rolling bearings as well.(c) 2022 COSPAR. Published by Elsevier B.V. All rights reserved.