Open Access. Powered by Scholars. Published by Universities.®

Political Science Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 3 of 3

Full-Text Articles in Political Science

High-Fidelity Simulation Of Small-Body Lander/Rover Spacecraft, Stefaan Van Wal Jan 2018

High-Fidelity Simulation Of Small-Body Lander/Rover Spacecraft, Stefaan Van Wal

Aerospace Engineering Sciences Graduate Theses & Dissertations

The scientific return of spacecraft missions that explore solar system small bodies can be increased through the inclusion of surface exploration with deployed probes. In this dissertation, a methodology is presented that allows for fast, parallel simulation of bouncing trajectories of arbitrary-shaped ballistic probes in the small-body environment. This enables planning of probe deployment and operation, and supports their inclusion on future missions.

The coarse small-body shape is modeled using an implicit signed distance field (SDF) that allows for fast collision detection. Statistical features are included onto the SDF using procedural generation techniques. The small-body gravity field is captured using ...


Low-Thrust Many-Revolution Trajectory Optimization, Jonathan David Aziz Jan 2018

Low-Thrust Many-Revolution Trajectory Optimization, Jonathan David Aziz

Aerospace Engineering Sciences Graduate Theses & Dissertations

This dissertation presents a method for optimizing the trajectories of spacecraft that use low-thrust propulsion to maneuver through high counts of orbital revolutions. The proposed method is to discretize the trajectory and control schedule with respect to an orbit anomaly and perform the optimization with differential dynamic programming (DDP). The change of variable from time to orbit anomaly is accomplished by a Sundman transformation to the spacecraft equations of motion.

Sundman transformations to each of the true, mean and eccentric anomalies are leveraged for fuel-optimal geocentric transfers up to 2000 revolutions. The approach is shown to be amenable to the ...


Review Of Railgun Modeling Techniques: Computation Of Railgun Force And Other Key Factors, Nathan James Eckert Jan 2017

Review Of Railgun Modeling Techniques: Computation Of Railgun Force And Other Key Factors, Nathan James Eckert

Aerospace Engineering Sciences Graduate Theses & Dissertations

Currently, railgun force modeling either uses the simple “railgun force equation” or finite element methods. It is proposed here that a middle ground exists that does not require the solution of partial differential equations, is more readily implemented than finite element methods, and is more accurate than the traditional force equation. To develop this method, it is necessary to examine the core railgun factors: power supply mechanisms, the distribution of current in the rails and in the projectile which slides between them (called the armature), the magnetic field created by the current flowing through these rails, the inductance gradient (a ...