Byron Davis
(Advisor: Prof. Gunter)

will propose a doctoral thesis entitled,

The Improvement of Multi-Satellite Orbit Determination through the Incorporation of Intersatellite Ranging Observations

On

Wednesday, December 2 at 11:00 a.m.
Remote (https://gatech.webex.com/meet/bdavis70)

Abstract
For many satellite remote sensing and communications missions, particularly those involving a formation or constellation of satellites, having precise knowledge of the satellite’s position in both an absolute and relative sense is essential. However, the capabilities of Global Navigation Satellite System (GNSS) based precise orbit determination (POD) alone and a priori knowledge of orbital dynamics parameters may not be enough to support an application’s needs. In an effort to improve multi-satellite POD, this thesis seeks to make the following three contributions:

• Quantify the potential gains to overall absolute and relative POD when additional intersatellite range observations are combined with standard GNSS observations for a constellation
• Assess the improvement that the incorporation of intersatellite ranges (ISRs) would provide constellations with respect to co-estimating corrections to non-spherical gravity terms and atmospheric drag models, and the degree to which these corrections help inform and improve the science return of larger dedicated gravity field missions
• Determine the expected POD performance, and subsequent system requirements, for a constellation with ISL capabilities operating in a partially or fully GNSS-denied environment

The GNSS+ISL POD and dynamics parameter estimation scheme is described and illustrated through a series of simulated case studies involving constellations of satellites in low Earth orbit (LEO).  Models for simulating realistic clock error, phase center variations, and carrier phase/pseudorange GNSS observation error were derived directly from hardware experimentation. Other sources of measurement error and dynamics uncertainty were based on current best estimates and practices found in the literature to create a robust and realistic simulation environment.  The precision of intersatellite ranging observations were also varied to represent different spacecraft platform capabilities, such as CubeSats. Simulations, POD, and parameter estimation were carried out using Mission Analysis, Operations, and Navigation Toolkit Environment (MONTE), which is the Jet Propulsion Laboratory’s signature astrodynamic analysis tool.

Committee

• Prof. Brian C. Gunter – School of Aerospace Engineering (advisor)
• Prof. Glenn Lightsey – School of Aerospace Engineering
• Prof. Koki Ho – School of Aerospace Engineering
• Dr. Eric Gustafson – Navigation Engineer, Jet Propulsion Laboratory
• Dr. Jill Seubert – Navigation Engineer, Jet Propulsion Laboratory