Successive Convexification for Passively-Safe Spacecraft Rendezvous on Near Rectilinear Halo Orbit

TL;DR

This paper introduces a sequential convex programming method for fuel-efficient, passively-safe spacecraft rendezvous on near rectilinear halo orbits, accounting for uncertainties and ensuring safety at all times.

Contribution

It develops a novel optimization approach combining SCP and chance constraints to guarantee passive safety and robustness in lunar orbit rendezvous scenarios.

Findings

Successfully demonstrated on realistic Gateway rendezvous simulation.

Ensures safety and constraint satisfaction throughout the trajectory.

Accounts for uncertainties in orbital insertion, actuation, and navigation.

Abstract

We present an optimization-based approach for fuel-efficient spacecraft rendezvous to the Gateway, a space station that will be deployed on a near rectilinear halo orbit (NRHO) around the Moon. The approach: i) ensures passive safety and satisfies path constraints at all times, ii) meets the specifications for critical decision points along the trajectory, iii) accounts for uncertainties that are common in real-world operation, such as due to orbital insertion, actuation, and navigation measurement, via chance constraints and utilizes a stabilizing feedback controller to bound the effect of uncertainties. We leverage sequential convex programming (SCP) and isoperimetric reformulation of path constraints, including passive safety, to eliminate the risk of inter-sample constraint violations that is common in existing methods. We demonstrate the proposed approach on a realistic simulation of a rendezvous to the Gateway.