The architecture of a system which enables the cost-effective exploration of the solar system is proposed. Such a system will make use of the benefits of the natural dynamics represented in the Circular Restricted Three-Body Problem (CRTBP). Additionally, a case study of the first missions which apply the lessons from the CRTBP is examined. The guiding principle of the proposed system is to apply lessons learned from both the Apollo project for deep space exploration and the International Space Station for long term habitation in space as well as modular space vehicle design. From this preliminary system design, a number of missions are outlined. These missions form the basis of an evolvable roadmap to fully develop the infrastructure required for long-term sustained manned exploration of the solar system. This roadmap provides a clear and concise pathway from current exploration capabilities to the current long-term goal of sustained manned exploration of Mars. The primary method employed in designing the staging orbits is the "Single Lunar Swingby", each of the component segment trajectory design processes is explored in detail. Additionally, the method of combining each of these segments together in a larger End-to-End optimizer environment within the General Mission Analysis Tool (GMAT) is introduced, called the Multiple Shooting Method. In particular, a specific Baseline Parking Orbit, or BPO, is chosen and analyzed. This BPO serves as the parking home orbit of any assets not currently in use. A BPO of amplitude (14000, 28000, 6000) kilometers. The BPO has full coverage to both the Earth and the Moon and orbit station-keeping may be conducted at a cost of less than 1 m/s over a 14 year period. This provides a cost-effective platform from which more advanced exploration activities can be based, both robotic and manned. One of the key advanced exploration activities considered is manned exploration of Mars, one of the current long-term goals of NASA. Trajectories from the BPO to Mars and back to Earth are explored and show approximately 50% decrease in required ΔV provided by the spacecraft.

In this work, capturing Near-Earth Asteroids (NEAs) into Near-Earth orbits is investigated. A general optimization strategy is employed whereby a genetic algorithm is used to seed a sequential quadratic programming (SQP) method for the first step, and then nearby solutions seed further SQP runs. A large number of solutions are produced for several asteroids with varying levels of thrust, and under the effects of various perturbations. Solutions are found over a range of epochs and times of flight as opposed to many traditional methods of optimizing point solutions. This methodology proved effective, finding low-thrust capture solutions within 10% of the required Delta V for analytically estimated transfers, and matching results from other optimization programs such as MALTO. It is found that the effects of solar radiation pressure (SRP) and n-body effects do not have a significant impact on the optimized transfer costs, nor do the perturbations significantly affect the shapes and trends of the optimized solution space. <p><br></p> <p>These optimized results are then used to develop analytic models for both optimized transfer costs and flight times. These models are then used to estimate the transfer costs and flight times for all listed Near Earth Asteroids from the JPL Small Body Database. This analysis is then used to determine the nominal properties of potentially capturable asteroids. The characteristics are then related to a series of different asteroid transfer technologies, elucidating each technology's capabilities and potential capture targets. Finally, this analysis concludes with a brief roadmap of the major decisions mission designers should consider for future asteroid capture missions.</p>

Saturn’s moon, Titan, has been a scientific marvel since Cassini’s flyby discovered methane-ethane lakes in the northern hemisphere. Several science missions to explore these lakes have been proposed, but none have been launched. Using these previous mission designs, as well as the success of the Huygens probe, this paper will discuss the development of a deployable multi-buoy system with the intent of studying the methane-ethane lakes. The buoys will study the chemical makeup of the lakes, determine meteorology of Titan atmosphere, and map the depth and floor of the targeted lakes. This thesis is a concept study on the multi-buoy system that reviews briefly the concept and design.

This thesis serves to provide a conceptual mission design for a Titan-orbiting stellar occultation mission. Titan has a significant atmosphere much like Earth's. An improved understanding of Titan's atmosphere could provide valuable information about the evolution of Earth's climate. Titan's atmosphere is known to be in a state of superrotation, wherein the atmosphere rotates significantly faster than the surface beneath. The details of the creation and sustainment of this extreme state on Titan in terms of angular momentum exchange remain unknown despite current theories and models. These unknowns, alongside inconsistencies between current models with observations from the Cassini mission, call for an urgent need for Titan atmospheric observations able to resolve atmospheric waves. The science objectives driving the mission design include maximizing the number of measurements, the latitude versus longitude coverage, the latitude versus local solar time coverage, and the mission duration. These measurement needs can be met by a Titan orbiter utilizing a refractive stellar occultation technique. Refractive stellar occultation observes starlight bending through an atmosphere as stars set behind a body. The observed bending profile can be inverted to infer density, temperature, and pressure profiles. This research uses Systems Tool Kit (STK) as a simulation tool to predict measurement coverage for various orbits. The orbital radius was determined to be the driving independent variable which set all other design variables, including the orbital plane which was uniquely selected for a given orbital radius to maximize the number of occultations. The results of this study show that a lower orbital radius is desired as this produces the best combination of measurement number and distribution. This orbital plane should be closely aligned with the Milky Way galactic plane to see the most stars occult. For the lowest sustainable orbital altitude, Low Titan Orbit (LTO) at 1200 km, the orbital plane should be nearly polar to maximize the number of occultations and latitude coverage. The optimal orbit selection (defined by orbital elements a = 3775 km, e = 0, i = 85 degrees, Ω = 87 degrees, ω = 0 degrees, and ν = 0 degrees) for a single satellite can produce nearly 400 stellar occultation opportunities per orbit and provide full latitude versus longitude coverage. A single satellite shows gaps in latitude versus local solar time coverage at mid-latitudes normal to the satellite ground track which may inhibit the diagnosis of the angular momentum flux associated with thermal tides. If necessary, a second satellite in an orbit orthogonal to the first is suggested to close coverage gaps to provide full local time coverage over a Titan day. The optimal orbit selection of this second satellite (defined by orbital elements a = 3775 km, e = 0, i = 5.3 degrees, Ω = 5.9 degrees, ω = 0 degrees, and ν = 0 degrees) provides an additional 343 occultation opportunities per orbit and increases latitude versus local solar time coverage by a factor of 1.5. The understanding of Titan's Earth-like atmosphere could provide insight into climate evolution here on Earth. This concept proposes a novel approach to improving this understanding. / Master of Science / This thesis serves to provide a conceptual mission design for a Titan-orbiting stellar occultation mission. Titan, one of Saturn's 82 moons, has a significant atmosphere much like Earth's. An improved understanding of Titan's atmosphere could provide valuable information about the evolution of Earth's climate. Titan's atmosphere is known to be in a state of superrotation, wherein the atmosphere rotates significantly faster than the surface beneath. The details of the creation and sustainment of this extreme state on Titan remain unknown despite current theories and models. These unknowns, alongside inconsistencies between current models with observations from the Cassini mission, call for an urgent need for Titan atmospheric observation. The science objectives driving the mission design include maximizing the number of measurements, the latitude versus longitude coverage, the latitude versus local solar time coverage (on a 24-hour scale), and the mission duration. These measurement needs can be met by a Titan orbiter utilizing a refractive stellar occultation technique. Refractive stellar occultation observes starlight bending through an atmosphere as stars set behind a body. The observed bending profile can be inverted to infer density, temperature, and pressure profiles. This research uses a simulation tool to predict measurement coverage for various orbits. The radius of the orbit was determined to be the driving independent variable which set all other design variables, including the orbital plane which was uniquely selected for a given orbital radius to maximize the number of occultations. The results of this study show that a lower orbital radius is desired as this produces the best combination of measurement number and distribution. This orbital plane should be closely aligned with the Milky Way galactic plane to see the most stars occult. For the lowest sustainable orbital altitude, Low Titan Orbit (LTO) at 1200 km, the orbital plane should be nearly polar to maximize the number of occultations and latitude coverage. The optimal orbit selection for a single satellite can produce nearly 400 stellar occultation opportunities per orbit and provide full latitude versus longitude coverage. A single satellite shows gaps in latitude versus local solar time coverage at mid-latitudes normal to the satellite ground track which may inhibit the diagnosis of atmospheric waves tied to Titan's night and day cycle. If necessary, a second satellite in an orbit orthogonal to the first is suggested to close coverage gaps to provide full local time coverage over a Titan day. The optimal orbit selection of this second satellite provides an additional 343 occultation opportunities per orbit and increases latitude versus local solar time coverage by a factor of 1.5. The understanding of Titan's Earth-like atmosphere could provide insight into climate evolution here on Earth. This concept proposes a novel approach to improving this understanding.

This thesis describes and evaluates the design of nanospacecraft based on advanced multifunctional microsystems building blocks. These systems bring substantial improvements of the performance of nanosatellites and enable new space exploration, e.g. interplanetary science missions using minute space probes. Microsystems, or microelectromechanical systems, allows for extreme miniaturization using heritage from IC industry. Reducing mass and volume of spacecraft gives large savings in terms of launch costs. Definition and categorization of system and module level features in multifunctional microsystems are used to derive a spacecraft optimization algorithm which is compatible with commonly used concurrent engineering methods. The miniaturization of modules enables modular spacecraft architectures comprising powerful multifunctional microsystems, which are applicable to satellites between 10 and 1000’s of kg. This kind of complete spacecraft architecture has been developed for the NanoSpace-1 technology demonstrator satellite. The spacecraft bus uses multifunctional design to enable distributed intelligence and autonomy, graceful degradation, functional surfaces, and distributed power systems. The increase in performance of the new spacecraft architecture as compared with conventional nanosatellites is orders of magnitudes in terms of power storage, scientific payload mass ratio, pointing stabilization, and long time space operation. This high-performance system-of-microsystems architecture has been successfully employed on two space robotic concepts: a miniaturized submersible vehicle for Jupiter’s Moon Europa and a miniaturized spherical robot. The submersible is enabled by miniaturization of electronics into 3-dimensional, vertically integrated multi-chip-modules together with new interconnection methods. These technologies enabled the submersible vehicle tube-shaped design within 20 cm length and 5 cm diameter. The spherical rover was developed for long range and networked science investigations of interplanetary bodies. The rover weighs 3.5 kg and is shown to endure direct reentry on Mars, which increases the ratio between the landed mobile payload mass and the initial mass in Mars orbit by a factor of 18.

<div>In order to answer the most pressing scientific questions about the two Martian moons, Phobos and Deimos, new remote sensing observations are required. The best way to obtain global high resolution observations of Phobos and Deimos is through dedicated missions to each body that utilize close-proximity orbits, however much of the orbital tradespace is too unstable to realistically or safely operate a mission.</div><div><br></div><div>This thesis explores the dynamics and stability characteristics of trajectories near Deimos. The family of distant retrograde orbits that are inclined out of the Deimos equatorial plane, known as quasi-satellite orbits, are explored extensively. To inform future mission design and CONOPS, the sensitivities and stability of distant retrograde and quasi-satellite orbits are examined in the vicinity of Deimos, and strategies for transferring between DROs are demonstrated. Finally, a method for designing quasi-satellite science orbits is demonstrated for a set of notional instruments and science requirements for a Deimos remote sensing mission.<br></div>

<p>Unexplained signals emanating from the pervasive Venusian clouds have intrigued scien- tists for more than half a century. Efforts to account for a myriad of perplexing measurements have motivated the development of new atmospheric missions to Venus. Fulfillment of science objectives in the inhospitable Venusian environment necessitates a range of mission archi- tectures, each of which poses significant design challenges which guide the development of new technologies. Missions of greater scope require increasingly intricate sample collection and measurement techniques, leading inevitably to the demand for long-duration science operations within the clouds. Sustained flight in the Venusian atmosphere may be afforded by high-altitude balloons. As such platforms have been studied extensively for terrestrial applications, it is prudent to consider which designs are most suitable for a given set of science goals. We present four balloon design options to accommodate Venus atmospheric science missions. We discuss system masses, envelope volumes, material characteristics, and mechanisms for altitude control as determined by the science objectives and cloud condi- tions. We consider three variations of a baseline mission architecture and corresponding gondola designs accommodating their distinct science instrument suites. The scientific value of long-duration in situ atmospheric sampling is surpassed only by the return of Venusian cloud material to Earth for investigation in a laboratory setting. Sample capture, orbit ac- quisition, and subsequent return to Earth may be accommodated by a high-altitude balloon, rocket, and rendezvous vehicle. Precise understanding of the balloon-rocket dynamics inside the clouds is required for launch attitude acquisition and may inform sample capture strat- egy. We present a generalized dynamical model for a balloon-gondola system. We model the system as a triple-spherical-floating-compound pendulum (TSFCP). Dynamical analyses of pendular motion frequently rely on the use of Eulerian angles as generalized coordinates, in- evitably resulting in the residence of trigonometric functions in the denominator. We present nonsingular equations of motion in terms of Euler parameters. We characterize a notional Venus sample return platform and simulate its motion in the Venusian atmosphere. We discuss the behavior of the system in response to wind gusts and initial perturbation. We consider limitations of the model as well as opportunities for its extension into future work.</p>

An integral part of NASA's vision for the coming years is a sustained infrastructure in cislunar space. The current baseline trajectory for this facility is a Near Rectilinear Halo Orbit (NRHO), a periodic orbit in the Circular Restricted Three-Body Problem. One of the goals of the facility is to serve as a proving ground for human spaceflight operations in deep space. Thus, this investigation focuses on transfers between the baseline NRHO and a family of periodic orbits that originate from a period-doubling bifurcation along the halo family. This new family of orbits has been termed the ``butterfly" family. This investigation also provides an overview of the evolution for a large subset of the butterfly family. Transfers to multiple subsets of the family are found by leveraging different design strategies and techniques from dynamical systems theory. The different design strategies are discussed in detail, and the transfers to each of these regions are compared in terms of propellant costs and times of flight.

The Auroral Acceleration Region (AAR) is a key region in understanding the interactionbetween the Magnetosphere and Ionosphere. To understand the physical, spatial, and temporal features of the region, multi-point measurements are required. Distributed small-satellite missions such as constellations of multiple nano satellites (for example multi-unit CubeSats) would enable such type of measurements. The capabilities of such a mission will highly depend on the number of satellites - one reason that makes low-cost platforms like CubeSats a very promising choice. In a previous study, the state-of-the-art of miniaturized payloads for AAR measurements was analyzed and evaluated on the capabilities of different multi-CubeSat configurations equipped with such payloads in addressing different open questions in AAR. This thesis will provide the mission analysis of such a multi-CubeSat mission to the AAR and possible mission design. This includes defining the mission scenario and associated requirements, developing a mathematical description of AAR that allows for specific regions in space to be targeted, an optimisation process for designing orbits targeting these regions, conversion of a satellite formation to appropriate orbits, verifying the scientific performance of this formation and the various costs associated with entering, maintaining, and exiting these orbits.

<p>Multiple Signals of Opportunity (multi-SoOp) across different frequencies and polarizations</p> <p>offer a potential breakthrough for remote sensing of root-zone soil moisture (RZSM). Deeper penetration depths of existing communication transmissions in the frequency ranges of 137–138, 240–270, and 360–380 MHz enable the estimation of RZSM by complementing global navigation satellite system reflectometry (GNSS-R) in L-band. The small form factor of the multi-SoOp observatory allows for high spatiotemporal coverage of RSZM by a satellite constellation in a cost-effective manner. This study aims to develop models and tools to define mission requirements for various system parameters that affect observation accuracy and coverage, for the advancement of spaceborne multi-SoOp remote sensing. These parameters include frequency and polarization combinations, observation error, inter-frequency temporal coincidence, and configuration of the satellite constellation. We present the development of a retrieval algorithm and the sensitivity analysis of retrieval accuracy. The retrieval algorithm was evaluated using synthetic observations generated from multiyear time series of in-situ soil moisture (SM) and satellite-based vegetation data. The combined use of both high and low frequencies improves retrieval accuracy by limiting uncertainties from vegetation and surface SM and providing sensitivity to deeper layers. A bivariate model, derived from the sensitivity analysis, facilitates error prediction for future science missions. We introduce a framework for tradespace exploration of the multi-SoOp satellite constellation. A constellation design study indicates that a Walker constellation comprising 24 satellites with 3 orbital planes at 500 km and 50° inclination optimizes the coverage and mission cost under mission requirements. A tower-based field experiment validated the performance of a prototype antenna for multi-SoOp using the interference pattern technique. More field experiments with improved instruments are required to further advance the multi-SoOp technique.</p>