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University of Colorado
1.
Handzo, Ryan E.
Satellite Navigation Using High Definition Television Signals.
Degree: MS, 2016, University of Colorado
URL: https://scholar.colorado.edu/asen_gradetds/189 
► Spacecraft operators can use a variety of observables to perform orbit determination throughout a mission. Currently the mission design community has an interest in…
(more)
▼ Spacecraft operators can use a variety of observables to perform orbit determination throughout a mission. Currently the mission design community has an interest in both autonomous spacecraft operations and in crewed, cis-lunar space missions. Navigators are focusing on ensuring resiliency and redundancy for satellites in the event that a navigation system fails. A spacecraft navigation system that utilizes high definition television (HDTV) signals is explored in this thesis. Using HDTV signals as the source for navigation observables, a satellite navigator can perform orbit determination (OD), either as the primary navigation source or as a backup navigation system. HDTV signals provide strong orbital coverage due to their prevalence around the world. It is shown that due to the high transmission powers HDTV signals are broadcast the signals can be received by satellites out to cis-lunar environments. The ability to extract accurate timing information from the signals in real time is demonstrated at a low CPU resource draw through the implementation of field-programmable gate arrays (FPGA). With the timing extracted from the signals, simulations show that accurate OD for satellites in lunar distant retrograde and halo orbits can be performed using only HDTV signals. These simulations are performed using the DE431 planetary ephemeris, planetary gravity, and solar radiation pressure in both an extended Kalman filter and square root information filter. The full satellite state, range and range-rate biases, and spacecraft reflectance are all successfully estimated by the filters with the presence of errors in the models of the systems dynamics. Since these signals are broadcast around the world at all times, they provide a free signal source for a satellite to utilize at any time more navigation information is needed or a back-up navigation source is required.
Advisors/Committee Members: Jeffrey S. Parker, Dennis Akos, Webster Cash.
Subjects/Keywords: spacecraft navigation; satellites; HDTV; signals; Aerospace Engineering
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APA (6th Edition):
Handzo, R. E. (2016). Satellite Navigation Using High Definition Television Signals. (Masters Thesis). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/189
Chicago Manual of Style (16th Edition):
Handzo, Ryan E. “Satellite Navigation Using High Definition Television Signals.” 2016. Masters Thesis, University of Colorado. Accessed March 07, 2021.
https://scholar.colorado.edu/asen_gradetds/189.
MLA Handbook (7th Edition):
Handzo, Ryan E. “Satellite Navigation Using High Definition Television Signals.” 2016. Web. 07 Mar 2021.
Vancouver:
Handzo RE. Satellite Navigation Using High Definition Television Signals. [Internet] [Masters thesis]. University of Colorado; 2016. [cited 2021 Mar 07].
Available from: https://scholar.colorado.edu/asen_gradetds/189.
Council of Science Editors:
Handzo RE. Satellite Navigation Using High Definition Television Signals. [Masters Thesis]. University of Colorado; 2016. Available from: https://scholar.colorado.edu/asen_gradetds/189
University of Colorado
2.
Bezrouk, Collin J.
Ballistic Capture into Lunar and Martian Distant Retrograde Orbits.
Degree: PhD, Aerospace Engineering Sciences, 2016, University of Colorado
URL: https://scholar.colorado.edu/asen_gradetds/147
► Distant retrograde orbits (DROs) are a neutrally stable class of three-body orbits. Because of their stability, DROs cannot be targeted with a low-energy transfer…
(more)
▼ Distant retrograde orbits (DROs) are a neutrally stable class of three-body orbits. Because of their stability, DROs cannot be targeted with a low-energy transfer along a stable manifold like unstable three-body orbits in the circular restricted three-body problem (CR3BP). However, in more complicated dynamical models, the effects of small perturbing forces can be exploited to build ballistic capture trajectories (BCTs) into DROs. We develop a method for building sets of BCTs for a particular reference DRO with recommendations for minimizing computational effort. Sets of BCTs are generated in the Earth-Moon system and the Mars-Phobos system due to their applicability to near-term missions and large difference in mass parameters. These BCT sets are stochastically analyzed to determine the range of conditions necessary for using a BCT, such as energy, solar system geometry, and origin. The nature of the DRO after the spacecraft is captured is studied, including minor body flyby altitudes and variations in the size and shape over time.
After a spacecraft has used a BCT, it can decrease its sensitivity to perturbations and extend its mission duration with a series of stabilizing maneuvers. Quasi-periodic orbits are constructed in the Earth-Moon CR3BP that lie on the boundary of stability, and closely resemble the DROs that result from using a BCT. Minimum cost transfers are then constructed between these quasi-periodic orbits and a target periodic DRO using a variety of methods for searching and optimizing. It is discovered that BCTs that target planar quasi-periodic DROs can be stabilized for about 15% of the cost of stabilizing a BCT with large out-of-plane motion.
Once a spacecraft is in a stable DRO, the long duration evolution of that orbit is of interest. Using a high fidelity dynamical model and numerical precision techniques, the evolution of several DROs in the Earth-Moon system is studied over a period of 30,000 years. The perturbing forces that cause a DRO to transition into an unstable orbit are identified and analyzed. DROs larger than 60,000~km grow in amplitude due to solar gravity until they depart the Moon after several centuries. DROs smaller than 45,000~km remain stable for 25,000 years or more, but decay in size due to the Moon'
s solid tide bulge, which eventually causes the DRO to depart the Moon. The DROs evolve chaotically and occasionally experience periods of relatively fast amplitude growth when the period of the DRO is in resonance with the frequency of particular perturbing forces.
Advisors/Committee Members: Jeffrey S. Parker, Daniel Scheeres, Daniel Kubitschek, Elizabeth Bradley, Daven Henze.
Subjects/Keywords: ballistic capture; distant retrograde orbit; low-energy; mission design; Phobos; weak stability boundary; Aerospace Engineering
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APA (6th Edition):
Bezrouk, C. J. (2016). Ballistic Capture into Lunar and Martian Distant Retrograde Orbits. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/147
Chicago Manual of Style (16th Edition):
Bezrouk, Collin J. “Ballistic Capture into Lunar and Martian Distant Retrograde Orbits.” 2016. Doctoral Dissertation, University of Colorado. Accessed March 07, 2021.
https://scholar.colorado.edu/asen_gradetds/147.
MLA Handbook (7th Edition):
Bezrouk, Collin J. “Ballistic Capture into Lunar and Martian Distant Retrograde Orbits.” 2016. Web. 07 Mar 2021.
Vancouver:
Bezrouk CJ. Ballistic Capture into Lunar and Martian Distant Retrograde Orbits. [Internet] [Doctoral dissertation]. University of Colorado; 2016. [cited 2021 Mar 07].
Available from: https://scholar.colorado.edu/asen_gradetds/147.
Council of Science Editors:
Bezrouk CJ. Ballistic Capture into Lunar and Martian Distant Retrograde Orbits. [Doctoral Dissertation]. University of Colorado; 2016. Available from: https://scholar.colorado.edu/asen_gradetds/147
University of Colorado
3.
Aziz, Jonathan David.
Low-Thrust Many-Revolution Trajectory Optimization.
Degree: PhD, 2018, University of Colorado
URL: https://scholar.colorado.edu/asen_gradetds/210
► 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…
(more)
▼ 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 inclusion of perturbations in the dynamic model, specifically aspherical gravity and third-body perturbations, and is improved upon through the use of modified equinoctial elements. An assessment of computational performance shows the importance of parallelization but that a single, multi-core processor is effective. The computational efficiency facilitates the generation of fuel versus time of flight trade-offs within a matter of hours. Many-revolution trajectories are characteristic of orbit transfers accomplished by solar electric propulsion about planetary bodies. Methods for modeling the effect of solar eclipses on the power available to the spacecraft and constraining eclipse durations are also presented. The logistic sunlight fraction is introduced as a coefficient that scales the computed power available by the fraction of sunlight available. The logistic sunlight fraction and Sundman-transformed DDP are used to analyze transfers from low-Earth orbit to geostationary orbit. The analysis includes a systematic approach to estimating the Pareto front of fuel versus time of flight. In addition to addressing many-revolution trajectories, this dissertation advances the utility of DDP in the three-body problem. Fuel-optimal transfers are presented in the Earth-Moon circular restricted three-body problem between distant retrograde orbits, between Lyapunov orbits and between Halo orbits. Those include mechanisms for varying the time of flight and the insertion point onto a target orbit. A multi-phase DDP approach enables initial guesses to be constructed from discontinuous trajectory segments. DDP is shown to leverage the system dynamics to find a heteroclinic connection between Lyapunov orbits, which is facilitated by the multi-phase approach.
Advisors/Committee Members: Daniel J. Scheeres, Shalom D. Ruben, Jeffrey S. Parker, Jacob A. Englander, Jay W. McMahon.
Subjects/Keywords: differential dynamic programming; low-thrust propulsion; solar electric propulsion; spaceflight; sundman transformation; trajectory optimization; Aerospace Engineering; Models and Methods
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APA (6th Edition):
Aziz, J. D. (2018). Low-Thrust Many-Revolution Trajectory Optimization. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/210
Chicago Manual of Style (16th Edition):
Aziz, Jonathan David. “Low-Thrust Many-Revolution Trajectory Optimization.” 2018. Doctoral Dissertation, University of Colorado. Accessed March 07, 2021.
https://scholar.colorado.edu/asen_gradetds/210.
MLA Handbook (7th Edition):
Aziz, Jonathan David. “Low-Thrust Many-Revolution Trajectory Optimization.” 2018. Web. 07 Mar 2021.
Vancouver:
Aziz JD. Low-Thrust Many-Revolution Trajectory Optimization. [Internet] [Doctoral dissertation]. University of Colorado; 2018. [cited 2021 Mar 07].
Available from: https://scholar.colorado.edu/asen_gradetds/210.
Council of Science Editors:
Aziz JD. Low-Thrust Many-Revolution Trajectory Optimization. [Doctoral Dissertation]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/asen_gradetds/210
University of Colorado
4.
De Smet, Stijn.
On the Design of Solar Gravity Driven Planetocentric Transfers Using Artificial Neural Networks.
Degree: PhD, 2018, University of Colorado
URL: https://scholar.colorado.edu/asen_gradetds/235
► The sun's gravity can be used to efficiently transfer between different planetocentric orbits. Such transfers cannot be designed in a two-body dynamical system, nor…
(more)
▼ The sun'
s gravity can be used to efficiently transfer between different planetocentric orbits. Such transfers cannot be designed in a two-body dynamical system, nor do analytical methods exist to identify such transfers. This dissertation presents a method to efficiently identify transfers between a specified departure and target orbit. This method is applied to a well known problem: transfers from inclined low-earth orbits to the geostationary orbit. Motivated by the large observed control authority of the sun for geocentric transfers, a new mission architecture is defined. This architecture allows the injection of multiple spacecraft around Mars in different target orbits, enabled by solar gravity driven orbital transfers. The efficient design of applications for a wide variety of departure and target orbits, requires an understanding of a large area of the phase space. This dissertation showcases how an artificial neural network architecture can accurately predict the solar gravity driven transfers, for a significantly large section of the phase space. The developed architecture is then used to efficiently identify transfers for several different applications. Multiple revolution transfers with maneuvers at intermediate periareions are identified that arrive at Phobos or Deimos. Furthermore, transfers are designed that transfer to both Phobos and Deimos in a single trajectory. In addition to addressing solar perturbed planetocentric transfers, this dissertation shows how the developed artificial neural network framework can be applied to a different problem, with different dynamics. As an example, the dissertation develops an artificial neural network architecture that can predict heteroclinic connections in the Earth-Moon circular restricted three-body problem.
Advisors/Committee Members: Daniel J. Scheeres, Natasha Bosanac, Jay McMahon, James D. Meiss, Jeffrey S. Parker.
Subjects/Keywords: artificial neural networks; astrodynamics; eccentric hill system; machine learning; periapse poincaré maps; Aerospace Engineering; Astrodynamics; Computer Sciences
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APA (6th Edition):
De Smet, S. (2018). On the Design of Solar Gravity Driven Planetocentric Transfers Using Artificial Neural Networks. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/235
Chicago Manual of Style (16th Edition):
De Smet, Stijn. “On the Design of Solar Gravity Driven Planetocentric Transfers Using Artificial Neural Networks.” 2018. Doctoral Dissertation, University of Colorado. Accessed March 07, 2021.
https://scholar.colorado.edu/asen_gradetds/235.
MLA Handbook (7th Edition):
De Smet, Stijn. “On the Design of Solar Gravity Driven Planetocentric Transfers Using Artificial Neural Networks.” 2018. Web. 07 Mar 2021.
Vancouver:
De Smet S. On the Design of Solar Gravity Driven Planetocentric Transfers Using Artificial Neural Networks. [Internet] [Doctoral dissertation]. University of Colorado; 2018. [cited 2021 Mar 07].
Available from: https://scholar.colorado.edu/asen_gradetds/235.
Council of Science Editors:
De Smet S. On the Design of Solar Gravity Driven Planetocentric Transfers Using Artificial Neural Networks. [Doctoral Dissertation]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/asen_gradetds/235
University of Colorado
5.
Hesar, Siamak Ghanizadeh.
A Framework for Precise Orbit Determination of Small Body Orbiting Spacecraft.
Degree: PhD, Aerospace Engineering Sciences, 2016, University of Colorado
URL: https://scholar.colorado.edu/asen_gradetds/141
► Spacecraft flying in close proximity of small bodies face a very complex dynamical environment with numerous types of perturbing forces acting on them. Development…
(more)
▼ Spacecraft flying in close proximity of small bodies face a very complex dynamical environment with numerous types of perturbing forces acting on them. Development of new techniques are needed for precise navigation of spacecraft in such environments. This study focuses on furthering our understanding of precise orbit determination of spacecraft in close proximity of small bodies via implementation of new methods for precise representation of strong and weak perturbing forces acting on spacecraft, such as the irregular gravitational field, strong solar radiation pressure effects, and thermal radiation pressure effects from the surface of small bodies.
Solar radiation pressure is a strong perturbing force acting on spacecraft in the orbital environment of small bodies that constantly pushes the spacecraft in a general direction away from the Sun. The existence of strong solar radiation pressure effects creates a complex dynamical environment around asteroids and comets that results in a particular set of orbital regimes, such as the family of the terminator or close to terminator orbits, whose dynamical evolution may not be intuitive. Small perturbations caused by maneuver errors and other sources may lead to large deviations in a spacecraft trajectory from its nominal orbit. Understanding the evolution of errors and uncertainties in the orbital elements of spacecraft is a crucial piece of mission planning and spacecraft navigation. In this thesis, we derive analytical expressions that govern the secular motion of the perturbed orbital elements in an environment that is strongly perturbed by the solar radiation pressure effects. Furthermore, we study a framework based on a Fourier series expansion for precise representation of the solar radiation pressure and small body surface thermal radiation pressure effects on spacecraft. This method is utilized in generating precise orbit determination solutions for simulated spacecraft in orbit about small bodies in the presence of dynamical and modeling errors.
Gravitational perturbations are other major disturbing forces in the proximity of a small body. This is especially true for spacecraft that come close to the surface of asteroids or comets in a landing or touch-and-go (TAG) scenario. Due to the irregular shape of these objects, a significant portion of the landing or TAG trajectory may lie inside a circumscribing sphere, where the conventional spherical harmonics expansion of the gravitational field is not convergent. Recent studies developed a so-called "interior" gravity field spherical harmonics expansion that extends down to the surface of the object without divergence issues. The interior gravity field, however, is not studied in the context of orbit determination and spacecraft navigation. This study investigates the feasibility of the utilization of such model to navigate spacecraft in a trajectory that is close to the surface of an irregularly shaped body of mass. The study will further examine the capability of estimating the spherical…
Advisors/Committee Members: Daniel J. Scheeres, Jeffrey S. Parker, Jay W. McMahon, Webster Cash, Shyam Bhaskaran.
Subjects/Keywords: Interior Gravity Field; Precise Orbit Determination; Small Body Navigation; Solar Radiation Pressure; Spacecraft Navigation; Thermal Radiation Pressure; Aerospace Engineering
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APA (6th Edition):
Hesar, S. G. (2016). A Framework for Precise Orbit Determination of Small Body Orbiting Spacecraft. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/141
Chicago Manual of Style (16th Edition):
Hesar, Siamak Ghanizadeh. “A Framework for Precise Orbit Determination of Small Body Orbiting Spacecraft.” 2016. Doctoral Dissertation, University of Colorado. Accessed March 07, 2021.
https://scholar.colorado.edu/asen_gradetds/141.
MLA Handbook (7th Edition):
Hesar, Siamak Ghanizadeh. “A Framework for Precise Orbit Determination of Small Body Orbiting Spacecraft.” 2016. Web. 07 Mar 2021.
Vancouver:
Hesar SG. A Framework for Precise Orbit Determination of Small Body Orbiting Spacecraft. [Internet] [Doctoral dissertation]. University of Colorado; 2016. [cited 2021 Mar 07].
Available from: https://scholar.colorado.edu/asen_gradetds/141.
Council of Science Editors:
Hesar SG. A Framework for Precise Orbit Determination of Small Body Orbiting Spacecraft. [Doctoral Dissertation]. University of Colorado; 2016. Available from: https://scholar.colorado.edu/asen_gradetds/141
University of Colorado
6.
Olikara, Zubin Philip.
Computation of Quasi-Periodic Tori and Heteroclinic Connections in Astrodynamics Using Collocation Techniques.
Degree: PhD, Aerospace Engineering Sciences, 2016, University of Colorado
URL: https://scholar.colorado.edu/asen_gradetds/144
► Many astrodynamical systems exhibit both ordered and chaotic motion. The invariant manifold structure organizes these behaviors and is a valuable tool for the design of…
(more)
▼ Many astrodynamical systems exhibit both ordered and chaotic motion. The invariant manifold structure organizes these behaviors and is a valuable tool for the design of spacecraft trajectories. The study of a system'
s dynamics often begins with the computation of its invariant tori (equilibrium points, periodic orbits, quasi-periodic orbits) and associated stable and unstable manifolds. Periodic orbits, in particular, have been used effectively for the design of low-energy transfers in the circular restricted 3-body problem (CR3BP). Quasi-periodic orbits offer similar benefits and are often more prevalent in the phase space, but additional complexities are involved in their computation. The foundation of this work is the development of a numerical method for computing two-dimensional quasi-periodic tori. The approach is applicable to a general class of Hamiltonian systems. Using a Fourier discretization and Gauss-Legendre collocation, a continuous representation of the torus is obtained. Included in the scheme is the computation of the torus'
s stable and unstable manifolds. These manifolds can then be used for the design of natural transfers. Two methods are presented for locating and continuing families of heteroclinic connections between quasi-periodic orbits in the CR3BP. A collocation-based approach for transitioning trajectories to a higher-fidelity ephemeris model is also included.
Advisors/Committee Members: Daniel J. Scheeres, Elizabeth Bradley, James D. Meiss, Jeffrey S. Parker, Hanspeter Schaub.
Subjects/Keywords: Gauss-Legendre collocation; heteroclinic connections; invariant manifolds; quasi-periodic orbits; restricted 3-body problem; spacecraft trajectory design; Aerospace Engineering; Applied Mathematics
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APA (6th Edition):
Olikara, Z. P. (2016). Computation of Quasi-Periodic Tori and Heteroclinic Connections in Astrodynamics Using Collocation Techniques. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/144
Chicago Manual of Style (16th Edition):
Olikara, Zubin Philip. “Computation of Quasi-Periodic Tori and Heteroclinic Connections in Astrodynamics Using Collocation Techniques.” 2016. Doctoral Dissertation, University of Colorado. Accessed March 07, 2021.
https://scholar.colorado.edu/asen_gradetds/144.
MLA Handbook (7th Edition):
Olikara, Zubin Philip. “Computation of Quasi-Periodic Tori and Heteroclinic Connections in Astrodynamics Using Collocation Techniques.” 2016. Web. 07 Mar 2021.
Vancouver:
Olikara ZP. Computation of Quasi-Periodic Tori and Heteroclinic Connections in Astrodynamics Using Collocation Techniques. [Internet] [Doctoral dissertation]. University of Colorado; 2016. [cited 2021 Mar 07].
Available from: https://scholar.colorado.edu/asen_gradetds/144.
Council of Science Editors:
Olikara ZP. Computation of Quasi-Periodic Tori and Heteroclinic Connections in Astrodynamics Using Collocation Techniques. [Doctoral Dissertation]. University of Colorado; 2016. Available from: https://scholar.colorado.edu/asen_gradetds/144
University of Colorado
7.
Parrish, Nathan Luis Olin.
Low Thrust Trajectory Optimization in Cislunar and Translunar Space.
Degree: PhD, 2018, University of Colorado
URL: https://scholar.colorado.edu/asen_gradetds/202
► Low-thrust propulsion technologies such as electric propulsion and solar sails are key to enabling many space missions which would be impractical with chemical propulsion.…
(more)
▼ Low-thrust propulsion technologies such as electric propulsion and solar sails are key to enabling many space missions which would be impractical with chemical propulsion. With exhaust velocities 10x higher than chemical rockets, electric propulsion systems can deliver a spacecraft to its target state for a fraction of the fuel. Due to the low thrust, the control must remain active for weeks or even years. When three-body dynamics are considered, the change in dynamics over the course of a trajectory can be extreme. This greatly complicates low-thrust mission design and navigation in cislunar and translunar space, making it an area of active research. Deterministic strategies for trajectory design and optimization rely on linearizing the problem and solving a series of linearized problems. In regimes with simple or slowly-varying dynamics, the linearization holds “true enough”, and we can easily arrive at a solution. However, three-body environments readily provide real cases where the linearization for all but the most carefully-chosen problem descriptions break down. This thesis presents a few modifications to existing algorithms to improve convergence. This thesis then uses this fast, robust method for trajectory optimization to generate training samples for a machine learning approach to optimal trajectory correction. We begin with one optimal low-thrust transfer. Then, we optimize thousands of transfers in the neighborhood of the nominal transfer. These transfers are described in the language of indirect optimal control, with the optimal control given as a function of Lawden’
s primer vector. We see that for a slightly different initial condition, the states and the costates both follow a slightly different trajectory to the target. A feedforward artificial neural network is trained to map the difference in states to the difference in costates, with a high degree of accuracy. Finally, we explore a potential application of this neural network: spacecraft that can navigate themselves autonomously in the presence of errors. We propose this as a method for future spacecraft that can optimally correct their trajectories without ground contacts. We demonstrate neural network navigation in two simplified dynamical environments: two-body heliocentric gravity, and the Earth-Moon circular restricted three body problem.
Advisors/Committee Members: Daniel J. Scheeres, Jeffrey S. Parker, Jay W. McMahon, Christoffer Heckman, Daniel Kubitschek.
Subjects/Keywords: artificial intelligence; crtbp; electric propulsion; neural networks; optimization; Aerospace Engineering; Engineering
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APA (6th Edition):
Parrish, N. L. O. (2018). Low Thrust Trajectory Optimization in Cislunar and Translunar Space. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/202
Chicago Manual of Style (16th Edition):
Parrish, Nathan Luis Olin. “Low Thrust Trajectory Optimization in Cislunar and Translunar Space.” 2018. Doctoral Dissertation, University of Colorado. Accessed March 07, 2021.
https://scholar.colorado.edu/asen_gradetds/202.
MLA Handbook (7th Edition):
Parrish, Nathan Luis Olin. “Low Thrust Trajectory Optimization in Cislunar and Translunar Space.” 2018. Web. 07 Mar 2021.
Vancouver:
Parrish NLO. Low Thrust Trajectory Optimization in Cislunar and Translunar Space. [Internet] [Doctoral dissertation]. University of Colorado; 2018. [cited 2021 Mar 07].
Available from: https://scholar.colorado.edu/asen_gradetds/202.
Council of Science Editors:
Parrish NLO. Low Thrust Trajectory Optimization in Cislunar and Translunar Space. [Doctoral Dissertation]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/asen_gradetds/202
University of Colorado
8.
Lathrop, Brian Wesley.
An Investigation of Alternate Transfer Strategies to the Sun-Earth Triangular Lagrangian Points.
Degree: PhD, Aerospace Engineering Sciences, 2014, University of Colorado
URL: https://scholar.colorado.edu/asen_gradetds/84
► Techniques for low energy transfers have been applied to constructing trajectories to various locations in the solar system. Previous techniques have concentrated on orbit…
(more)
▼ Techniques for low energy transfers have been applied to constructing trajectories to various locations in the solar system. Previous techniques have concentrated on orbit matching trajectory maneuvers and two-body transfers. This research investigates several strategies for low energy transfers that can be utilized to intersect desirable objects or locate to different equilibrium regions in the solar system. The principle tools utilized in this investigation stem from the three-body problem and the development of Lagrangian equilibrium points, periodic orbits and invariant manifolds. Another principle tool is the use of low thrust propulsion to develop low energy transfer trajectories utilizing long duration flight times. Of primary interest is the transfer to the Sun-Earth triangular equilibrium Lagrange points, commonly referred to as L
4 and L
5. Given the localized stability of these regions leading and trailing the Earth as it orbits the Sun, there is low cost to keep a spacecraft in these locations to perform scientific investigations. Of primary interest in the
S-E L
4/L
5 regions is the study of small body Trojan asteroids and near Earth objects, stereoscopic solar observations, and various space weather and early warning solar storm detection. This research attempts to minimize the trajectory transfer cost in terms of velocity maneuver impacts.
Advisors/Committee Members: George H. Born, Jeffrey S. Parker, Brandon Jones, Webster Cash, Rodney Anderson.
Subjects/Keywords: invariant manifolds; L4 L5; Lagrangian points; Low Energy Transfer; periodic orbits; three-body dynamics; Astrodynamics; Navigation, Guidance, Control and Dynamics
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APA (6th Edition):
Lathrop, B. W. (2014). An Investigation of Alternate Transfer Strategies to the Sun-Earth Triangular Lagrangian Points. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/84
Chicago Manual of Style (16th Edition):
Lathrop, Brian Wesley. “An Investigation of Alternate Transfer Strategies to the Sun-Earth Triangular Lagrangian Points.” 2014. Doctoral Dissertation, University of Colorado. Accessed March 07, 2021.
https://scholar.colorado.edu/asen_gradetds/84.
MLA Handbook (7th Edition):
Lathrop, Brian Wesley. “An Investigation of Alternate Transfer Strategies to the Sun-Earth Triangular Lagrangian Points.” 2014. Web. 07 Mar 2021.
Vancouver:
Lathrop BW. An Investigation of Alternate Transfer Strategies to the Sun-Earth Triangular Lagrangian Points. [Internet] [Doctoral dissertation]. University of Colorado; 2014. [cited 2021 Mar 07].
Available from: https://scholar.colorado.edu/asen_gradetds/84.
Council of Science Editors:
Lathrop BW. An Investigation of Alternate Transfer Strategies to the Sun-Earth Triangular Lagrangian Points. [Doctoral Dissertation]. University of Colorado; 2014. Available from: https://scholar.colorado.edu/asen_gradetds/84
University of Colorado
9.
Leonard, Jason Michael.
Supporting Crewed Missions using LiAISON Navigation in the Earth-Moon System.
Degree: PhD, Aerospace Engineering Sciences, 2015, University of Colorado
URL: https://scholar.colorado.edu/asen_gradetds/97
► Crewed navigation in certain regions of the Earth-Moon system provides a unique challenge due to the unstable dynamics and observation geometry relative to standard…
(more)
▼ Crewed navigation in certain regions of the Earth-Moon system provides a unique challenge due to the unstable dynamics and observation geometry relative to standard Earth-based tracking systems. The focus of this thesis is to advance the understanding of navigation precision in the Earth-Moon system, analyzing the observability of navigation data types frequently used to navigate spacecraft, and to provide a better understanding of the influence of a crewed vehicle disturbance model for future manned missions in the Earth-Moon system.
In this research, a baseline for navigation performance of a spacecraft in a Lagrange point orbit in the Earth-Moon system is analyzed. Using operational ARTEMIS tracking data, an overlap analysis of the reconstructed ARTEMIS trajectory states is conducted. This analysis provides insight into the navigation precision of a spacecraft traversing a Lissajous orbit about the Earth-Moon L
1 point. While the ARTEMIS analysis provides insight into the navigation precision using ground based tracking methods, an examination of the benefits of introducing Linked Autonomous Interplanetary Satellite Orbit Navigation (LiAISON) is investigated. This examination provides insight into the benefits and disadvantages of LiAISON range and range-rate measurements for trajectories in the Earth-Moon system.
In addition to the characterization of navigation precision for spacecraft in the Earth-Moon system, an analysis of the uncertainty propagation for noisy crewed vehicles and quiet robotic spacecraft is given. Insight is provided on the characteristics of uncertainty propagation and how it is correlated to the instability of the Lagrange point orbit. A crewed vehicle disturbance model is provided based on either Gaussian or Poisson assumptions. The natural tendency for the uncertainty distribution in a Lagrange point orbit is to align with the unstable manifold after a certain period of propagation. This behavior is influenced directly by the unstable nature of the orbit itself.
This thesis then examines several different LiAISON mission configurations to determine the benefits and disadvantages for future crewed missions in the Earth-Moon system. The following LiAISON supplemented configurations are analyzed over a wide trade space to determine their feasibility: 1) Geosynchronous and Earth-Moon halo orbiters; 2) A crewed vehicle in an Earth-Moon L
2 halo orbit with a navigation satellite orbiting another Earth-Moon Lagrange point; 3) A navigation satellite in an Earth-Moon halo orbit tracking a crewed vehicle in low lunar orbit; 4) A crewed vehicle on a trans-lunar cruise being tracked by a navigation satellite in an Earth-Moon halo orbit.
Advisors/Committee Members: George H. Born, Jeffrey S. Parker, Daniel J. Sheeres, Brandon A. Jones, Webster C. Cash.
Subjects/Keywords: Autonomous Navigation; Navigation; Orbit Determination; Stochastic Processes; Navigation, Guidance, Control and Dynamics; Space Vehicles
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APA (6th Edition):
Leonard, J. M. (2015). Supporting Crewed Missions using LiAISON Navigation in the Earth-Moon System. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/97
Chicago Manual of Style (16th Edition):
Leonard, Jason Michael. “Supporting Crewed Missions using LiAISON Navigation in the Earth-Moon System.” 2015. Doctoral Dissertation, University of Colorado. Accessed March 07, 2021.
https://scholar.colorado.edu/asen_gradetds/97.
MLA Handbook (7th Edition):
Leonard, Jason Michael. “Supporting Crewed Missions using LiAISON Navigation in the Earth-Moon System.” 2015. Web. 07 Mar 2021.
Vancouver:
Leonard JM. Supporting Crewed Missions using LiAISON Navigation in the Earth-Moon System. [Internet] [Doctoral dissertation]. University of Colorado; 2015. [cited 2021 Mar 07].
Available from: https://scholar.colorado.edu/asen_gradetds/97.
Council of Science Editors:
Leonard JM. Supporting Crewed Missions using LiAISON Navigation in the Earth-Moon System. [Doctoral Dissertation]. University of Colorado; 2015. Available from: https://scholar.colorado.edu/asen_gradetds/97
University of Colorado
10.
Herman, Jonathan F.C.
Improved Collocation Methods to Optimize Low-Thrust, Low-Energy Transfers in the Earth-Moon System.
Degree: PhD, Aerospace Engineering Sciences, 2015, University of Colorado
URL: https://scholar.colorado.edu/asen_gradetds/116
► Modern and near-future Solar Electric Propulsion capabilities enable many new missions that were inconceivable using chemical propulsion systems. Many of these involve highly complex…
(more)
▼ Modern and near-future Solar Electric Propulsion capabilities enable many new missions that were inconceivable using chemical propulsion systems. Many of these involve highly complex trajectories that are very challenging to design. New tools are needed that effectively utilize the rapidly growing parallel processing capabilities of modern computers. This research improves Gauss-Lobatto collocation methods, which are known to perform very well for low-thrust trajectory optimization, by formulating them as massively parallel processes. The parallelized elements of the problem formulation execute up to 11 times faster, depending on what force model is used and when evaluated by themselves. When accounting for the operations of the nonlinear programming solver, this translates to up to 3.7 times faster performance for solving a complete trajectory optimization problem, again depending on the force model that is used. The remaining barriers to further performance improvements, and the conditions upon which these depend, are clearly identified.
The implemented methods are combined into an optimization tool named Maverick. More general improvements to the formulation of the Gauss-Lobatto collocation methods are also developed and included in Maverick, which permit a more flexible use of these optimization schemes and enable them to find more complex solutions. One example of this is Maverick'
s ability to autonomously introduce gravity assists into trajectories, which greatly increases the utility and convergence radius of these methods.
In order to demonstrate the benefit of this work, three applications are studied. The first are transfers between halo-like orbits in the Earth-Moon system, which shows this is likely an unattractive region for missions like the New Worlds Observer. The second application investigates stabilization maneuvers in lunar distant retrograde orbits. This work demonstrates the feasibility of these stabilization transfers for a variety of sample return missions, such as the upcoming Asteroid Redirect Mission. The final application discussed is a series of multi-body low-thrust transfers from the Earth to the Moon that efficiently utilize highly variable dynamics to reduce propellant consumption, which is relevant for a variety of future mission concepts. These are computed for a wide range of flight times, showing that reductions up to 45% of the transfer time can be achieved with a propellant consumption as little as 0.5% of the total spacecraft mass. Up to 90% of the flight time can be eliminated for a propellant cost of 4% of the total spacecraft mass, or up to 83% for a propellant cost of less than 2%. The developed algorithm seamlessly transitions its solutions from full low-thrust, low-energy trajectories to the `pure' low-thrust trajectories that define the shortest transfer trajectories, validating its robust performance. Beyond these quanti_able results, these examples illustrate the complexity of the solutions that can be identified with these improved implementations…
Advisors/Committee Members: Jeffrey S. Parker, George Born, Brandon A. Jones, Jay McMahon, Bengt Fornberg.
Subjects/Keywords: Astrodynamics; Electric Propulsion; Low-Thrust Propulsion; Parallel computing; Trajectory Optimization; Aerospace Engineering
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APA ·
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APA (6th Edition):
Herman, J. F. C. (2015). Improved Collocation Methods to Optimize Low-Thrust, Low-Energy Transfers in the Earth-Moon System. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/116
Chicago Manual of Style (16th Edition):
Herman, Jonathan F C. “Improved Collocation Methods to Optimize Low-Thrust, Low-Energy Transfers in the Earth-Moon System.” 2015. Doctoral Dissertation, University of Colorado. Accessed March 07, 2021.
https://scholar.colorado.edu/asen_gradetds/116.
MLA Handbook (7th Edition):
Herman, Jonathan F C. “Improved Collocation Methods to Optimize Low-Thrust, Low-Energy Transfers in the Earth-Moon System.” 2015. Web. 07 Mar 2021.
Vancouver:
Herman JFC. Improved Collocation Methods to Optimize Low-Thrust, Low-Energy Transfers in the Earth-Moon System. [Internet] [Doctoral dissertation]. University of Colorado; 2015. [cited 2021 Mar 07].
Available from: https://scholar.colorado.edu/asen_gradetds/116.
Council of Science Editors:
Herman JFC. Improved Collocation Methods to Optimize Low-Thrust, Low-Energy Transfers in the Earth-Moon System. [Doctoral Dissertation]. University of Colorado; 2015. Available from: https://scholar.colorado.edu/asen_gradetds/116
University of Colorado
11.
Ko, Hyun Chul.
Representation of Unknown and Unmodeled Space Events for Satellites : Characteristics and Applications.
Degree: PhD, Aerospace Engineering Sciences, 2015, University of Colorado
URL: https://scholar.colorado.edu/asen_gradetds/120
► A new way of representing unknown and unmodeled space events (USEs) with Thrust-Fourier-Coefficients (TFCs) is introduced and its applications to satellite orbit determination (OD)…
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▼ A new way of representing unknown and unmodeled space events (USEs) with Thrust-Fourier-Coefficients (TFCs) is introduced and its applications to satellite orbit determination (OD) and event detection are studied. A USE is regarded as an event due to unknown changes of force model caused by unplanned maneuvers, unknown deployment, collision, or some other drastic change in space environment. A satellite'
s motion under USEs, transitioning between two arbitrary orbit states, can be represented as an equivalent orbital maneuver connecting those two states by applying the Fourier series representation of perturbing accelerations. This event representation with TFCs rigorously provides a unique control law that can generate the given secular behavior of a satellite due to a USE. This technique enables us to facilitate the analytical propagation of orbit information across a USE, which allows for the usage of an existing pre-event orbit solution to compute a post-event orbit solution. By directly appending TFCs and the represented event dynamics to a regular OD filter, the modified filter using TFCs is able to blend post-event tracking data to improve a post-event orbit solution in the absence of a dynamics model of USE. Case studies with simulated tracking data show that the event representation using TFCs helps to maintain OD across a period of USEs. In addition, when there is measurement data available during USEs, a modified sequential filter with TFCs is able to detect the onset and the termination time of an event. This event representation-based OD and event detection distinguishes itself from other approaches in that it does not rely on any assumption or a priori information of a USE. This generic approach enables us to fit tracking data in real time and therefore to maintain a satellite tracking in the presence of USEs. This method has the advantage of avoiding the difficulty of manual parameter tuning and, thus, is able to provide more accurate post-event OD solution with a single OD filter.
Advisors/Committee Members: Daniel J. Scheeres, George H. Born, John Hauser, Jay W. McMahon, Jeffrey S. Parker.
Subjects/Keywords: Event Detection; Event Representation; Maneuvering Satellite Tracking; Orbit Determination; Thrust-Fourier-Coefficients; Unknown Space Event; Mechanical Engineering; Navigation, Guidance, Control and Dynamics; Space Vehicles; Systems Engineering
Record Details
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Record Details
Similar Records
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❌
APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Ko, H. C. (2015). Representation of Unknown and Unmodeled Space Events for Satellites : Characteristics and Applications. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/asen_gradetds/120
Chicago Manual of Style (16th Edition):
Ko, Hyun Chul. “Representation of Unknown and Unmodeled Space Events for Satellites : Characteristics and Applications.” 2015. Doctoral Dissertation, University of Colorado. Accessed March 07, 2021.
https://scholar.colorado.edu/asen_gradetds/120.
MLA Handbook (7th Edition):
Ko, Hyun Chul. “Representation of Unknown and Unmodeled Space Events for Satellites : Characteristics and Applications.” 2015. Web. 07 Mar 2021.
Vancouver:
Ko HC. Representation of Unknown and Unmodeled Space Events for Satellites : Characteristics and Applications. [Internet] [Doctoral dissertation]. University of Colorado; 2015. [cited 2021 Mar 07].
Available from: https://scholar.colorado.edu/asen_gradetds/120.
Council of Science Editors:
Ko HC. Representation of Unknown and Unmodeled Space Events for Satellites : Characteristics and Applications. [Doctoral Dissertation]. University of Colorado; 2015. Available from: https://scholar.colorado.edu/asen_gradetds/120
. 
Open Access Theses and Dissertations