Design and performance of a Martian autonomous navigation system based on a smallsat constellation
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Author/Creator ORCID
Date
2022-11-30
Type of Work
Department
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Citation of Original Publication
"S. Molli et al. “Design and performance of a Martian autonomous navigation system based on a smallsat constellation.” Acta Astronautica 203 (February 2023): 112-124. https://doi.org/10.1016/j.actaastro.2022.11.041 "
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Subjects
Abstract
Deciphering the genesis and evolution of the Martian polar caps can provide crucial understanding of Mars’
climate system and will be a big step forward for comparative climatology of the terrestrial planets. The growing
scientific interest for the exploration of Mars at high latitudes, together with the need of minimizing the resources onboard landers and rovers, motivates the need for an adequate navigation support from orbit. In the
context of the ARES4SC study, we propose a novel concept based on a constellation that can support autonomous
navigation of different kind of users devoted to scientific investigations of those regions. We study two constellations, that differ mainly for the semi-major axis and the inclination of the orbits, composed of 5 small
satellites (based on the SmallSats design being developed in Argotec), offering dedicated coverage of the Mars
polar regions. We focus on the architecture of the inter-satellite links (ISL), the key elements providing both
ephemerides and time synchronization for the broadcasting of the navigation message. Our concept is based on
suitably configured coherent links, able to suppress the adverse effects of on-board clock instabilities and to
provide excellent range-rate accuracies between the constellation’s nodes. The data quality allows attaining good
positioning performance for both constellations with a largely autonomous system. Indeed, we show that ground
support can be heavily reduced by employing an ISL communication architecture. Periodic synchronization of
the clocks on-board the constellation nodes with terrestrial time (TT) is enabled through the main spacecraft (the
mother-craft), the only element of the constellation enabling radio communication with the Earth. We report on
the results of numerical simulations in different operational scenarios and show that a very high-quality orbit
reconstruction can be obtained for the constellation nodes using a batch-sequential filter or a batch filter with
overlapping arcs, that could be implemented on board the mother-craft, thus enabling a high level of navigation
autonomy. The assessment of the achievable positioning accuracy with this concept is fundamental to evaluate
the feasibility of a future positioning system providing a global coverage of the red planet.