An Algorithm to Engineer Autonomous Ballistic Capture at Mars

Current deep-space missions heavily count on ground-based operations. Although reliable, ground slots will saturate soon, so hampering the current momentum in space exploration. EXTREMA, a project awarded an ERC Consolidator Grant in 2019, enables self-driving spacecraft, challenging the current paradigm and aiming, among others, at autonomously engineering ballistic capture. This work presents an autonomous ballistic capture algorithm suitable for spacecraft with limited control authority and onboard resources. The algorithm is applied to construct BC corridors at Mars, time-varying manifolds supporting capture that can be targeted far away from the planet. The algorithm envisaged a novel methodology to generate families of ballistic capture orbits characterized by succeeding capture epochs. The families are built by correcting in sequence the initial conditions of ballistic capture orbits provided that they are enough regular. New orbits are obtained solving a well-posed three-point boundary value problem exhibiting 8 boundary conditions. The conditions are linearized, and the problem is solved for a finite set of variables with the multiple shooting technique. The computationally demanding problem of finding ballistic capture orbits through stable sets manipulation is unburdened by just solving a linear system, making the algorithm compatible with CubeSats onboard resources. An overview of the autonomous BC algorithm and the details of the correction procedure are provided. The methodology is applied to generate families of orbits belonging to capture sets C−11 and C−16 starting from the same baseline capture orbit. In both cases, the method constructs sequences of initial conditions spanning more than 100 days. The algorithm performance is assessed and its limitations are discussed. Results are inspected against the solar gravity gradient field to get insight about how the methodology acts when it corrects a reference solution into a new capture orbit.