Two-Leg Deep Space Relay Architectures: Performance, Challenges, and Perspectives

TL;DR

This paper analyzes two-leg deep space relay architectures using radio and optical links, evaluating their performance, challenges, and potential advantages over direct communication, with a focus on orbital configurations and relaying techniques.

Contribution

It provides a comprehensive analysis of two-leg relay architectures for deep space communication, comparing different technologies and configurations to identify performance benefits and challenges.

Findings

Two-leg architectures can match direct link data rates with smaller ground antennas.

Optical links offer higher data rates but require precise pointing.

Relaying techniques impact system performance and complexity.

Abstract

In this paper, architectures for interplanetary communications that feature the use of a data relay are investigated. In the considered "two-leg" architecture, a spacecraft orbiting the Earth, or in orbit at a Lagrange point, receives data from a deep space probe (leg-1) and relays them towards ground (leg-2). Different wireless technologies for the interplanetary link, namely, radio frequencies above the Ka band and optical frequencies, are considered. Moreover, the cases of transparent and regenerative relaying as well as different different orbital configurations are addressed, offering a thorough analysis of such systems from different viewpoints. Results show that, under certain constraints in terms of pointing accuracy and onboard antenna size, the adoption of a two-leg architecture can achieve the data rates supported by direct space-to-Earth link configurations with remarkably smaller ground station antennas.