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Full-Text Articles in Astrodynamics
A Nonlinear Least Squarees Approach To Orbit Determination In Near-Earth Orbits, Ryan M. Vorst
A Nonlinear Least Squarees Approach To Orbit Determination In Near-Earth Orbits, Ryan M. Vorst
Theses and Dissertations
This work explores relevant scenarios to implement a Frequency on Arrival method using nonlinear least squares to determine a transmitting satellite’s orbit based only on measurements of the received radio frequency. Multiple relevant collection geometries, such as a target in prograde low earth orbit, in retrograde low earth orbit, in sun synchronous orbit, in near-perigee highly elliptical orbit, in near-apogee highly elliptical orbit, and in geosynchronous orbit, are simulated to collect theoretical received frequency data. Once data collection has been simulated, the theoretical apparent frequencies recorded are used in a nonlinear least squares method with differential correction to find a …
Orbit Determination With Event-Based Cameras To Improve Space Domain Awareness, Conor M. Wisentaner
Orbit Determination With Event-Based Cameras To Improve Space Domain Awareness, Conor M. Wisentaner
Theses and Dissertations
The objective of this research is to assess the utility of a COTS EBC for SDA applications by evaluating its ability to produce data for orbit updates of resident space objects. Unlike traditional frame-based imaging sensors, the pixels on an EBC activate independently when a change in brightness is detected to produce a continuous data flow on a per pixel basis. This unique functionality provides much higher temporal resolution than traditional frame-based sensors, such that an EBC can generate far more data points from a single observation than a frame-based sensor. However, current COTS EBCs have less spatial resolution than …
Leveraging External Sensor Data For Enhanced Space Situational Awareness, Charlie T. Bellows
Leveraging External Sensor Data For Enhanced Space Situational Awareness, Charlie T. Bellows
Theses and Dissertations
Reliable Space Situational Awareness (SSA) is a recognized requirement in the current congested, contested, and competitive environment of space operations. A shortage of available sensors and reliable data sources are some current limiting factors for maintaining SSA. Unfortunately, cost constraints prohibit drastically increasing the sensor inventory. Alternative methods are sought to enhance current SSA, including utilizing non-traditional data sources (external sensors) to perform basic SSA catalog maintenance functions. Astronomical data, for example, routinely collects serendipitous satellite streaks in the course of observing deep space; but tactics, techniques, and procedures designed to glean useful information from those collects have yet to …
Trajectory Optimization For Spacecraft Collision Avoidance, James W. Sales Jr.
Trajectory Optimization For Spacecraft Collision Avoidance, James W. Sales Jr.
Theses and Dissertations
The last several decades have resulted in an unfortunate byproduct of space exploration and development: orbital debris. Satellites in Low Earth Orbit have been required to make an ever increasing number of course corrections in order to avoid collisions. Despite efforts to the contrary, collisions continue to occur, each time creating additional debris and increasing the requirement for the remaining satellites to maneuver. Every required maneuver decreases a satellite's service life. The purpose of this study is to develop a minimum thrust profile to maneuver an orbiting satellite out of its projected error ellipse before a collision occurs. For comparison, …
Application Of Kam Theorem To Earth Orbiting Satellites, Bryan D. Little
Application Of Kam Theorem To Earth Orbiting Satellites, Bryan D. Little
Theses and Dissertations
An orbit that lies on a Kolmogorov, Arnold, and Moser (KAM) Torus will remain on that torus until and unless it experiences a force that causes it to leave the torus. Earth satellites that are subject only to the Earth's gravity field may lie on such KAM tori. Analyzing on orbit satellite position data should allow for the identification of the fundamental frequencies needed to define the KAM tori for modeling Earth satellite orbits. KAM Tori are created for the Gravity Recovery and Climate Experience (GRACE) and Jason-1 satellites to model their orbital motion. Precise position data for the satellites …
Optimal Orbital Coverage Of Theater Operations And Targets, Kimberly A. Sugrue
Optimal Orbital Coverage Of Theater Operations And Targets, Kimberly A. Sugrue
Theses and Dissertations
The use of satellites as a tactical asset to support theater operations is a desired capability for future space operations. Unlike traditional satellite systems designed to provide coverage over the entire globe or large regions, tactical satellites would provide coverage over a small region which can be modeled as a single ground point defined by a latitude and longitude. In order to provide sufficient utility as a theater asset, a satellite should be placed in an orbit that provides a maximum amount of coverage of the target ground point. This study examined the optimization of orbit parameters to maximize the …