Space environment effects on the gravity probe B satellite control system
Abstract/Contents
- Abstract
- Gravity Probe B (GP-B) was a satellite-based physics experiment designed to test Einstein's General Theory of Relativity. Circling the Earth in a polar orbit, the spacecraft housed four spinning spherical gyroscopes and measured the inertial orientation of their spin axes. Based on the theory, two relativistic effects, the geodetic effect and the frame-dragging effect, were predicted to cause a drift of the gyroscope spin axes in perpendicular directions. GP-B made unprecedented measurements of both of these effects. The primary focus of this dissertation is an improvement to the GP-B spacecraft attitude estimation using an updated model based on the response of the control system to the space environment. Early data analysis revealed to 1% the influence of the geodetic effect in the motion of all four gyroscopes, but also illustrated the need to model and remove several systematic noise sources, in order to measure successfully the much smaller frame-dragging effect. Some disagreement in gyroscope drift rate estimates has been identified as a Newtonian torque, called the misalignment torque, and resulted from the interaction between electrical patches located on the gyroscope and housing surfaces. This torque caused a motion of the gyroscope spin axes that blended in with the science results, but that was modeled and removed from the data. This modeling required an improvement in satellite attitude estimation. The main contribution of the work described in this dissertation is to improve the spacecraft pointing knowledge, in order to model more effectively the misalignment torque disturbance. By modeling the response of the vehicle to the space environment, it was possible, in many cases, to reduce the pointing estimation uncertainty by a factor of two. Much of the improvement in satellite pointing estimation came from an improved understanding of the thermal space environment, specifically the thermal cycles that caused much of the vehicle motion that required additional terms in the attitude estimation model. The improvements made using the new model were used to generate a new time history of vehicle pointing for use in the GP-B data analysis.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2016 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Adams, Michael E |
|---|---|
| Associated with | Stanford University, Department of Aeronautics and Astronautics. |
| Primary advisor | DeBra, D. B. (Daniel B.) |
| Thesis advisor | DeBra, D. B. (Daniel B.) |
| Thesis advisor | Close, Sigrid, 1971- |
| Thesis advisor | Everitt, C. W. F. (C. W. Francis), 1934- |
| Thesis advisor | Rock, Stephen |
| Advisor | Close, Sigrid, 1971- |
| Advisor | Everitt, C. W. F. (C. W. Francis), 1934- |
| Advisor | Rock, Stephen |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Michael E. Adams. |
|---|---|
| Note | Submitted to the Department of Aeronautics and Astronautics. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2016. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2016 by Michael Edward Adams
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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