Design of a Continuous-Thrust Solar Polar Mission

Design of a Continuous-Thrust Solar Polar Mission

Van der Weg, W.J.

Ambrosius, B.A.C. (mentor)

Aerospace Engineering

Space Engineering

Astrodynamics & Space Missions

2010-05-12

Understanding the Sun's natural processes helps us to understand how the Earth responds to the Sun's variations and helps improve our ability to predict its behavior. A probe in polar orbit around the Sun would be able to help provide a more complete picture of the Sun by studying coronal features from various angles, by linking particle and field observation to images of the Sun, by determining the magnetic structures and convection patterns in the polar regions of the Sun, and by following the evolution of solar structures over a full solar rotation. Previous theses have tackled the transfer from Earth to Solar Polar Science Orbit by using solar sails to propel the spacecraft. An alternative is a spacecraft using solar electric propulsion. This offers the advantage of a spacecraft that is more maneuverable, less mechanically complex, and is based on proven technology. Unlike the solar sail spacecraft however, this requires the spacecraft to carry propellant onboard to perform the transfer. An almost entirely analytical implementation is constructed, featuring the use of the shape-based approach (exponential sinusoid) to model the transfer. The implementation connects multiple shapes by way of gravity assist at specified planets, and uses Edelbaum's theory to model the remaining necessary inclination change, to investigate a transfer from Earth to a solar polar orbit at 0.4 AU distance from the Sun. An optimal solution is sought using an optimization strategy consisting of a random (Monte Carlo) method to perform an initial exploration of the search space, a global (Genetic Algorithm) method, and a local (Nelder-Mead) search method to refine the optimum located by the global method. The goal is to minimize propellant mass and transfer time, while maintaining a realistic transfer that does not violate various imposed constraints (such as departure and arrival velocity). Two solar electric propulsion options are offered (one performing a swing-by at Venus and another performing a swing-by at Jupiter), and compared to a reference solar sailing design. After experimentation it was found that the model is useful for simpler transfers, but a more involving implementation (using multiple separate coasting and thrust arcs) is required to give it the means to tackle more intricate problems. In addition, a more in-depth exploration of the inclination change maneuvers would be beneficial (especially with regards to a distance constrained maneuver).

Sun
Solar Polar

http://resolver.tudelft.nl/uuid:9d5b3d65-fee6-4e53-91fc-837d16835121

2010-06-02

Student theses

master thesis

(c) 2010 Van der Weg, W.J.