Engineering Commons^™

Supersonic Retro-Propulsion Computational Fluid Dynamics Analysis Applied To Future Mars Mission, Margarita Nataly Brandt

Doctoral Dissertations and Master's Theses

Supersonic Retro-Propulsion is one of the most promising emerging technologies being considered by NASA for use in future Mars missions. This new form of Entry Descent Landing has the potential to help increase the allowable payload mass currently constraining many science instruments and operations. Computational Fluid Dynamics was used to show the feasibility of supersonic retro - propulsion in Mars atmospheric conditions. The results presented show the SRP will be able to perform satisfactory using the same conditions that the Curiosity Rover was exposed to during its landing sequence. The plume expansion was analyzed for various cases, moving from free …

Modeling And Simulation Of Radiation From Electronic Transitions In Hypersonic Atmospheric Reentry Flow, Curtis Scholz

Doctoral Dissertations and Master's Theses

A capability for higher accuracy heat transfer modeling in CFD for hypersonic re-entry flows, via inclusion of thermal radiation, is sought. With temperatures reaching tens of thousands of degrees, radiation is known to be significant to chemical reaction rates and thermal boundary layer development, hence surface heat transfer and thermal ablation both to the heat shield and the backshell region of re-entry vehicles. Two current NASA solicitations seek such an improved capability relative to the Mars and Earth entry problems, as uncertainty typically leads to overdesign and excess weight. The present research develops a first physics-based “building block,” which computes …

Cubesat Wakes In The Earth’S Ionosphere, Robert M. Albarran Ii

Doctoral Dissertations and Master's Theses

Space exploration is currently being revolutionized by the advent of the CubeSat: 10cm cubed satellites that typically deploy in constellations for less than $100,000. Spacecraft instrumentation design must be redefined to abide by the compact CubeSat payload. Furthermore, the CubeSat dimension must be considered with respect to characteristic length scales of the space plasma environment, namely, the Debye length. Although spacecraft-plasma interactions- surface charging, plasma sheaths and wakes- have been well-studied for larger satellites, they are less understood for CubeSats.

The Dynamic Ionosphere CubeSat Experiment (DICE) is a 1.5U CubeSat which recently ended its mission. DICE carried two fixed-bias Langmuir …

The Effect Of The 2-Dimensional Magnetic Field Profile In Hall Thrusters, Megan Lewis Harvey

Doctoral Dissertations and Master's Theses

Electric propulsion engines, in particular Hall thrusters, provide the possibility of long-distance, low-cost space travel. The geometrical details of the Hall thrusters, especially the magnetic field prole, are crucial to improving their efficiency. The effect of the magnetic field structure was investigated using a simple, two-dimensional model, assuming axial symmetry. The previous one-dimensional conclusion, namely that the details of the shape of the magnetic field are unimportant, was confirmed. This result has implications for the design of future Hall thruster engines, with an eye toward maximizing their efficiency.

Investigation Of A Lagrangian-Point Propellant Depot Rendezvous Approach For An Interplanetary Mission To Mars, Joshua W. Ehrlich

Doctoral Dissertations and Master's Theses

This thesis investigates the feasibility of a refueling station for a beyond Earth orbit (BEO) mission. The propellant depot is located at the L₂ -Lagrangian point within the Earth-Moon system. This investigation determines if a refueling mission will reduce propulsive energy requirements necessary for Earth departure of a BEO-vehicle to achieve an interplanetary transfer to Mars. Furthermore, this research presents a trade study which identifies approximate total requirements for a direct and rendezvous mission to Mars as well as the necessary fuel masses to complete each approach. This analysis provides conclusive information in determining the benefits in utilizing a …

A Gap Analysis Of Meteorological Requirements For Commercial Space Operators, Nicholas Stapleton

Doctoral Dissertations and Master's Theses

Commercial space companies will soon be the primary method of launching people and supplies into orbit. Among the critical aspects of space launches are the meteorological concerns. Laws and regulations pertaining to meteorological considerations have been created to ensure the safety of the space industry and those living around spaceports; but, are they adequate? Perhaps the commercial space industry can turn to the commercial aviation industry to help answer that question. Throughout its history, the aviation industry has dealt with lessons learned from mishaps due to failures in understanding the significance of weather impacts on operations. Using lessons from the …

The Effects Of Familiarity And Persuasion On Risk Assessment, Casey L. Smith

Doctoral Dissertations and Master's Theses

Cognitive biases influence decisions and the analyses of risk. They are often derived from two separate processes: bias based on familiarity (familiarity bias) and bias as the result of influences from outside sources (persuasion bias). Research suggests that familiarity-based bias may lead to acceptance of an activity's drawbacks and a leniency of its risks.

In addition, research has tried to measure and analyze different types of biases individually, but few have compared the interactions of more than one bias at once. Because different biases may derive from different mental phenomena it is important to tease out the distinctions, and observe …

Spacecraft And Propulsion Technician Error, Daniel Clyde Schultz

Doctoral Dissertations and Master's Theses

Commercial aviation and commercial space similarly launch, fly, and land passenger vehicles. Unlike aviation, the U.S. government has not established maintenance policies for commercial space. This study conducted a mixed methods review of 610 U.S. space launches from 1984 through 2011, which included 31 failures. An analysis of the failure causal factors showed that human error accounted for 76% of those failures, which included workmanship error accounting for 29% of the failures. With the imminent future of commercial space travel, the increased potential for the loss of human life demands that changes be made to the standardized procedures, training, and …

Preliminary Design Of An Asteroid Hopping Mission, Michael D. Scheppa

Doctoral Dissertations and Master's Theses

In 2010, NASA announced that its new vision is to support private space launch operations. It is anticipated that this new direction will create the need for new and innovative ideas that push the current boundaries of space exploration and contain the promise of substantial gain, both in research and capital.

The purpose of the study is to plan and estimate the feasibility of a mission to visit a number of near Earth asteroids (NEAs). The mission would take place before the end of the 21st century, and would only use commercially available technology. Throughout the mission design process, while …

Removal Of Biofilm Through Controlled Cavitation, Mathew Chackalackal Mathew

Master's Theses - Daytona Beach

Human kind is poised to take the next "giant step" in space exploration, the manned mission to Mars, among other things. But before any plans for such long term habitation on an alien planet, there has to be consideration towards prevention and removal of bacterial contamination. Bacterial contamination or rather degradation of materials was considered of negligible importance. Bacterial degradation can be serious for long-term manned space mission, more so because there is no way to obtain quick replacements. For such conditions, a new innovative way of bacterial removal has been proposed wherein the bacteria is removed with no damage …

Control System Design And Simulation Of Spacecraft Formations Via Virtual Formation Approach, Pavan Donepudi

Master's Theses - Daytona Beach

The problem of formation control of multiple spacecraft using the virtual structure approach is studied. The thesis first summarizes the progress made in the area of spacecraft formation control and then provides an overview of the virtual structure method. Modifying earlier established control design techniques, new feedback laws are constructed to control both the rotational and translational motion of a group of spacecraft. Several computer simulations are performed to illustrate the effectiveness of the modified control laws. The ephemeris and attitude data files generated via Matlab are exported to Satellite Tool Kit (STK) to create 3D animations. Various formation scenarios …

Parameter Estimation Of Spacecraft Fuel Slosh Using Pendulum Analogs, Keith L. Schlee

Master's Theses - Daytona Beach

The nutation (wobble) of a spinning spacecraft in the presence of energy dissipation is a well-known problem in dynamics and is of particular concern for space missions. Its rate of growth is characterized by the Nutation Time Constant (NTC). For analytical prediction of the NTC, fuel slosh is often modeled using simple mechanical analogs such as pendulums or rigid rotors coupled to the spacecraft. Identifying model parameter values which adequately represent the sloshing dynamics is the most important step in obtaining a good NTC estimate. Currently, the identification of the model parameters is a laborious trial-and-error process in which the …

Maneuvering Control Of A Spacecraft With Propellant Sloshing, Philip A. Savella

Master's Theses - Daytona Beach

Propellant slosh has been a problem studied in spacecraft designs since the early days of large, liquid-fuel rockets. The conventional design solution involves physical structures inside the fuel tanks that limit propellant motion. Although effective, baffles and bladders add to spacecraft mass and structural complexity. In this research, the sloshing fuel mass is treated as an unactuated degree of freedom within a rigid body. Specifically, the propellant is modeled as a pendulum mass anchored at the center of a spherical tank. After obtaining the coupled equations of motion, several linear controllers are developed to achieve planar spacecraft pitch-maneuvers while suppressing …

Modeling And Slew-Maneuver Control Of A Flexible Spacecraft, Jeremy E. Eckhart

Master's Theses - Daytona Beach

Slew-maneuver control problem is studied for a flexible spacecraft consisting of a rigid main body to which a long flexible appendage is attached. Nonlinear dynamical system models are developed using both distributed parameter modeling and discrete parameter modeling; these models are shown to be equivalent for appropriately chosen system parameters. Lyapunov-based nonlinear feedback controllers are designed for the control of rigid-body motion while suppressing the lowest frequency vibrational mode. In case of large-angle maneuvers, these nonlinear controllers are shown to outperform the linearization-based controllers including the filtered proportional-derivative (PD) controllers as well as the linear quadratic regulator (LQR) controllers. Finally, …

Control System Design And Simulation Of Spacecraft Formations, Daniel Dyer

Master's Theses - Daytona Beach

The objective of this thesis is to analyze an effective control scheme for a formation of spacecraft, implement that control, and provide a 3-D simulation. The thesis first summarizes the progress made in formation flight control schemes and then provides a theoretical framework for the control system design. Using established control design techniques, feedback laws are constructed to control both rotational and translational motion of a group of spacecraft. Computer simulations are carried out using Matlab to generate the ephemeris and attitude data, which are exported to Satellite Tool Kit (STK) to create animations. The process by which Matlab is …

Modeling Launch Vehicle Success Using Artificial Neural Networks, Jennifer A. Schuck

Master's Theses - Daytona Beach

Expendable launch vehicles in the United States currently have a reliability of 92%. The failures that do occur cost millions of dollars in spacecraft replacement, lost revenue, and other expenses. These costs are passed on in higher insurance rates and launch vehicle price. If the launch outcome of the launch vehicles could be better predicted, the overall cost of launching payloads into space would decrease. This study used artificial neural networks to model the overall launch outcome of a launch vehicle so that the results of a launch could be predicted. Two neural network architectures--MLP and fuzzy ARTMAP--were trained on …

An Experimental Investigation Of Direct And Indirect Viewing Of A Remote Manipulation, Stephen N. Plishka

Master's Theses - Daytona Beach

The purpose of this study was to evaluate direct and indirect viewing of a remote manipulation. With continued exploration of inner and outer space, the ability to directly manipulate objects is lost due to the nature of operating in harsh environments. Remote viewing and operation of equipment is used in such things as the space shuttle manipulator arm, orthoscopic surgery, undersea exploration, and hazardous material management. Most of these operations do not have the luxury of direct viewing. This study will compare the effects of direct viewing vs. indirect viewing from three different viewing distances of 20cm, 60cm and 100cm.

Cooperative Power-Limited Optimal Rendezvous Between Many Spacecraft, Virginie Guerre

Master's Theses - Daytona Beach

The minimum fuel rendezvous problem between several power-limited low-thrust spacecraft neighboring either a circular or an elliptic orbit is investigated. Both cooperative and non cooperative maneuvers are studied. The maximum principle of Pontryagin is applied to the optimal control rendezvous problem of several spacecraft. The gravitational field models investigated are the Clohessy-Wiltshire field and the inverse-square gravity field. Numerical solutions using a shooting method and the finite difference method are used in order to determine the trajectories of the spacecraft. Unlike previous investigations, this work is not restricted to a rendezvous of two spacecraft around a circular orbit, but a …