Trajectory Design for the ESA LISA Mission

TL;DR

This paper presents an optimized trajectory design for the ESA LISA mission, including transfer and science orbit optimization, navigation analysis, and error mitigation strategies to ensure stable formation in space.

Contribution

It introduces a combined transfer and science orbit optimization approach for LISA, along with detailed navigation and error analysis to enhance mission stability.

Findings

Optimal transfer $ ext{Δ}v$ of 1092 m/s per spacecraft for 2034 launch

Corner angle variation maintained at approximately $60^ ext{o} extpm 1^ ext{o}$

Navigation corrections can reduce insertion errors to preserve constellation stability

Abstract

The three Laser Interferometer Space Antenna (LISA) spacecraft are going to be placed in a triangular formation in an Earth-trailing or Earth-leading orbit. They will be launched together on a single rocket and transferred to that science orbit using Solar Electric Propulsion. Since the transfer $\Delta v$ depends on the chosen science orbit, both transfer and science orbit have been optimised together. For a thrust level of 90 mN, an allocation of 1092 m/s per spacecraft is sufficient for an all-year launch in 2034. For every launch month a dedicated science orbit is designed with a corner angle variation of close to $60^\circ \pm 1.0^\circ$ and an arm length rate of maximum 10 m/s. Moreover, a detailed navigation analysis of the science orbit insertion and the impact on insertion errors on the constellation stability has been conducted. The analysis shows that Range/Doppler measurements together with a series of correction manoeuvres at the beginning of the science orbit phase can reduce insertion dispersions to a level where corner angle variations remain at about $60^\circ \pm 1.1^\circ$ at $99\%$ C.L.. However, the situation can become significantly worse if the self-gravity accelerations acting during the science orbit phase are not sufficiently characterised prior to science orbit insertion.