Exploration of optimal orbits in the strongly perturbed environment of the 2001 SN263 triple asteroid system

Exploration of optimal orbits in the strongly perturbed environment of the 2001 SN263 triple asteroid system

Obrecht, G.

Doornbos, E.N. (mentor)
Cowan, K. (mentor)

Aerospace Engineering

Astrodynamics and Space Missions

2016-06-03

For the past 20 years, the small bodies of the solar system, such as asteroids and comets, have been increasingly gathering the interest of scientists and space agencies. The latter have been multiplying the number of space missions to study them. Brazil does not want to be left out and has been working on its own mission, ASTER, which has the particularity of having as a target a triple asteroid system. Although adding great scientific interest to the mission, this characteristic considerably complicates the mission design, by making the space probe move in a complex gravitational field and submitting it to very strong perturbations forces. Following the past researches on the ASTER mission, which mostly dealt with the characterisation of the 2001 SN263 asteroid system, this work focuses on the preliminary design of mission orbits suitable for the exploration of the asteroids. Two phases of the mission are considered: the arrival in the system, which requires a parking orbit; and the exploration phase. For the latter, two scenarios are studied: a parallel and a sequential observations of the system. To find the optimal orbits for each of these cases, a computer tool has been designed, which comprises an orbit integrator able to propagate the trajectory of a spacecraft within the asteroid system, and an optimiser which uses evolutionary algorithms to find optima from a 5-dimensional search space in a single- or multi-dimensional objective space, according to objective functions that can be chosen and adapted to match the case considered. The computer tool performs well for all cases, and allows to draw general conclusions on which kind of orbits to consider for the ASTER mission. The results show that the solar radiation pressure is by far the most problematic perturbation and is hence driving the properties of the solutions. Among all cases, many optima are terminator orbits, which are by nature strong against solar radiation perturbations. Moreover, orbits closer to the bodies are more stable, and any trajectory too distant from the bodies will be blown away. This work concludes on the suitability of the optimisation methods selected to the orbit design for this mission, although it is advised to still improve the software to model the dynamics of the system in a more detailed manner, and on recommendations for the ASTER mission. No satisfying parking orbit has been found and the relative strength of the solar radiation pressure implies that there does not exist orbits sufficiently remote from the bodies to serve as parking orbits. It is recommended to investigate other solutions with active orbit maintenance. As for the exploration phase, the sequential observation scheme shows its superiority. Satisfying observation orbits can be found about all three bodies, which is not the case for the parallel observation because of the zones of instability present in-between the bodies.

orbit
optimization
asteroids
triple asteroid
perturbations
four body problem
ASTER

http://resolver.tudelft.nl/uuid:c5e0bc71-db3a-4619-a658-b0a773f45904

Student theses

master thesis

(c) 2016 Obrecht, G.