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Attitude control system failures are often mission ending even when the mission payload remains operational. In this dissertation, the concept of unscented guidance is applied to reorient a reaction wheel satellite in the absence of feedback from star trackers or an inertial measurement unit (IMU). It is shown that an open-loop maneuver, properly designed using optimal control theory, can be used to achieve terminal attitude errors that are comparable with closed-loop control in the presence of uncertainty in the satellite inertia tensor. Typically, coarse closed-loop control is used to achieve < 1 degree pointing accuracy before more accurate pointing is done using fine guidance sensors to close the loop for science acquisition. It is shown that reaction wheel maneuvers designed using unscented guidance can also achieve sub-degree pointing accuracy of the spacecraft, making control hand-off to a functioning fine pointing control mode possible. The approach presented here enables large angle attitude control to be recovered so that mission operations may be continued despite IMU or star tracker failures., DoD Space, Chantilly, VA 20151, Civilian, Department of the Navy, Approved for public release. Distribution is unlimited.

The objective of the study was to develop the initial capabilities enabling the eventual automation of an antenna gain-to-noise-temperature (G/T) measurement process using a software defined radio. This research investigated how to improve the Mobile Cubesat Command and Control (MC3) network’s ability to remotely monitor a ground station’s health. Previous thesis work was leveraged to collect baseline data and process it using software created by the Space Dynamics Laboratory for the MC3 program. The thesis required hands-on use of the NPS MC3 ground station and other stations on the network. The results of this thesis demonstrate that a software defined radio is capable of collecting and processing radio frequency signals from the sun and cold sky to produce a G/T value with enough fidelity to assess the health of the station’s downlink radio frequency chain. Continued expansion of the collected frequency range by the software defined radio is recommended to provide a broader assessment of the antenna’s sensitivity to weak, space-borne signals.

The objective of this research was to design, build, and test the next iteration of a low-cost, high-bandwidth X-band software-defined radio (SDR). The flight version of this iteration of the payload will be integrated into a commercially provided 6U bus to transmit and receive data, commands, and telemetry between the satellite and the MC3 network. The spacecraft reference design included two other payloads and used the Astro Digital Corvus-6 bus as the baseline for defining payload-bus-ground interfaces. This project utilized MATLAB Simulink to program the SDR. The SDR will primarily operate in the store-and-forward mode for transmissions when in line-of-sight of a ground station. The up/down convert board was designed, and manufacturing options were explored. Additionally, this project finalized the mechanical enclosure and bus interfaces. The payload aimed to maintain a 0.5U CubeSat form-factor and achieve a data rate of up to 10 Mbps with 1e-5 bit error rate. Following design and construction, the hardware and software components were subjected to functional end-to-end testing to evaluate performance. Further flight qualification will subject the payload to environmental testing to ensure survivability through launch and the expected low-Earth orbit environment., Lieutenant, United States Navy, Approved for public release. distribution is unlimited

The Naval Postgraduate School (NPS) Small Satellite Lab places heavy emphasis on the research, development, and integration of emerging technologies on future spacecraft. An integral part of the advancement of these technologies is the ability to test them in real-world environmental conditions. CubeSats remain a viable choice for rapid prototyping and proof-of-concept testing. Delivering CubeSats to near-space environments is a method of demonstrating the feasibility of these new technologies. Amateur high-power rocketry offers an additional platform to augment the already existing high-altitude balloons by delivering payloads containing the new technologies and CubeSat form factor small satellites to near-space environments. Previous NPS research has produced a single stage high-power rocket capable of attaining an approximate altitude of 11.9 km (39,000 feet) above ground level. This thesis applies optimal control theory to develop a multi-stage rocket capable of altitudes in excess of what was previously reached by both high-altitude balloons and the previously designed high-power rocket., Lieutenant, United States Navy, Approved for public release. distribution is unlimited

Empirical heat transfer values and thermodynamic models were verified and expanded for a uni-element film-cooled liquid rocket engine operating on a gaseous oxygen and RP-1 mixture. This effort was motivated by the likely reduction of the overall engine mass by integrating regenerative cooling channels directly into the combustion chamber and nozzle walls through the use of additive manufacturing. The data was collected for a range of operating conditions from 1.77 to 2.29 oxidizer-to-fuel mass mixture ratio and 9.65% to 19.69% film cooling. The combustion chamber of the engine experienced damage at heat flux values of 4.54 MW/m2 that occurred at a chamber pressure of 6.96 MPa, a mixture ratio of 2.0, and 9.59% film cooling. The data collected was used with computational tools to develop a novel integrated chamber-nozzle engine design for both regenerative cooling and film cooling conditions. The final design possessed less than 6% variation of flow though the 18 regenerative liner passages and was predicted to be able to handle the current and expected heat transfer values. The unit was printed using Stainless Steel 17-4PH with additive manufacturing techniques but will need to be qualified with future open and closed-loop testing to evaluate the delivered regenerative cooling effectiveness.

The configurable fault-tolerant processor (CFTP) project was intended to develop the means for a system to operate in areas which include frequent single-effect events (SEEs) similar to those caused by ionized radiation colliding with logic gates. Such errors are capable of degrading the functionality of a system and completely changing a state machine, such as is at the heart of most spacecrafts’ processors. The method for this consisted of a field-programmable gate array (FPGA) being designed into a system which is capable of detecting and then correcting SEEs. The system was designed by many students. This project will take that design, which launched into space earlier this year, and reduce it to modules which can be uploaded individually, built around a core which will be part of the existing triple fault-tolerant design (TFTD). Modularizing the code allows more experiments to be simultaneously performed in the future by changing the architecture of the system to upload specific modules to specified addresses. This will allow smaller uploads and code tweaks, without incurring long upload times, and more frequent updates to run specific tests ad hoc. Research and development conducted for this thesis has demonstrated the capability to inject configuration errors into the current design and the TFTD’s ability to detect those and similar errors, contributing to a better understanding of the TFTD., http://archive.org/details/modularizationof1094563984, Lieutenant, United States Navy, Approved for public release; distribution is unlimited.

Channel-response-based physical-layer authentication systems are challenged by the use of millimeter-wave frequencies for wireless communications due to the reduced coherence time and the sparsity of multipath components typically encountered. We examine how such an environment makes the assumptions of previous works in physical-layer authentication unrealistic, and present an approach that can tolerate such challenges by anticipating channel-response features based on relatively simple environmental survey information and location information of the communicating nodes. In addition to its resilience to millimeter-wave channel phenomena, such an approach has the advantage of being independent of an alternative initial authentication mechanism, distinguishing it from the majority of previous channel-based physical-layer authentication works and enabling its use in multi-factor authentication. Our work examines to what extent multipath time delays caused by planar specular reflectors enable the authentication of a wireless user’s reported position. Our formulations are supported via simulation of multiple environments, and the efficacy of the proposed scheme is supported via analysis of its information entropy and the likelihood that a masquerading attempt will be inadvertently authenticated. The analysis indicates useful information entropy and miss rates can be achieved provided measurement error is adequately bounded., http://archive.org/details/gmillimeterwavep1094564010, Lieutenant Commander, United States Navy, Approved for public release; distribution is unlimited.

The Naval Postgraduate School (NPS) Small Satellite Lab places heavy emphasis on the research, development, and integration of emerging technologies on future spacecraft. An integral part of the advancement of these technologies is the ability to test them in real-world environmental conditions. CubeSats remain a viable choice for rapid prototyping and proof-of-concept testing. Delivering CubeSats to near-space environments is a method of demonstrating the feasibility of these new technologies. Amateur high-power rocketry offers an additional platform to augment the already existing high-altitude balloons by delivering payloads containing the new technologies and CubeSat form factor small satellites to near-space environments. Previous NPS research has produced a single stage high-power rocket capable of attaining an approximate altitude of 11.9 km (39,000 feet) above ground level. This thesis applies optimal control theory to develop a multi-stage rocket capable of altitudes in excess of what was previously reached by both high-altitude balloons and the previously designed high-power rocket.

The objective of this research was to design, build, and test the next iteration of a low-cost, high-bandwidth X-band software-defined radio (SDR). The flight version of this iteration of the payload will be integrated into a commercially provided 6U bus to transmit and receive data, commands, and telemetry between the satellite and the MC3 network. The spacecraft reference design included two other payloads and used the Astro Digital Corvus-6 bus as the baseline for defining payload-bus-ground interfaces. This project utilized MATLAB Simulink to program the SDR. The SDR will primarily operate in the store-and-forward mode for transmissions when in line-of-sight of a ground station. The up/down convert board was designed, and manufacturing options were explored. Additionally, this project finalized the mechanical enclosure and bus interfaces. The payload aimed to maintain a 0.5U CubeSat form-factor and achieve a data rate of up to 10 Mbps with 1e-5 bit error rate. Following design and construction, the hardware and software components were subjected to functional end-to-end testing to evaluate performance. Further flight qualification will subject the payload to environmental testing to ensure survivability through launch and the expected low-Earth orbit environment.

In the next few years, the Space Systems Academic Group (SSAG) and the Small Satellite Laboratory at the Naval Postgraduate School (NPS) may begin work on a small satellite swarm constellation. This thesis introduces flight operations concepts for small satellite formations conducting sparse aperture radar missions to inform decision makers at NPS of possible flight operations options. An orbital modeling program called Systems Tool Kit was used to simulate combinations of flight patterns and orbits, including a pendulum and a helix inline hybrid model, and a cartwheel hybrid model. The MATLAB software package was used to plot the simulated orbits, calculating the flight formation stability, and for calculating the relative effects of sensor separation on the system resolution. Findings include a stable dispersion pattern for the satellites to conduct their mission and an ability to maintain safe, collision-free flight operations., http://archive.org/details/smallsatellitesw1094561306, Major, United States Army, Approved for public release; distribution is unlimited.

Software-defined radios (SDRs) are used in many communications applications and offer flexibility in designing a communication network by offering rapid configuration changes after the radio is already produced. This is of interest in the small satellite industry, where small, lightweight, low-cost, and programmable radios will be needed for a wide array of upcoming missions of increasing complexity. Previous Naval Postgraduate School (NPS) research has produced a C-band SDR payload in a 1U CubeSat form factor. The X-band of the radio frequency spectrum offers more bandwidth, and opens the possibility of higher data rate transmissions. The objective for this project was to build an X-band SDR that can be used in future NPS research and flown on multiple platforms, including high altitude balloons, high altitude rockets, and CubeSats. This project built on previous C-band SDR research by converting the transmissions to X-band, expanding the over-air software protocol, implementing a new waveform, increasing the over-air data rate, and assessing the overall performance of the system., DoD Space, http://archive.org/details/xbandsoftwaredef1094563431, Outstanding Thesis, Lieutenant Commander, United States Navy, Approved for public release; distribution is unlimited.

This study examines how to reconstruct a satellite decryption process from source information. It examines how cryptographic algorithms are implemented in software and what software components are required to access data in a useable format. This examination enabled the reverse engineering and reconstruction of the decoding processes utilized by the three PropCubes: Merryweather, Fauna, and Flora. Transmitted data from these PropCubes was analyzed to verify the validity of the developed decryption and data handling Python scripts. A concept of operations for implementing the reconstructed decryption and data handling processes in real-time is discussed in this research.

The current Department of Defense (DoD) satellite communications (SATCOM) network consists of large, exquisite, and expensive constellations providing service across the radio frequency spectrum. However, the current SATCOM architecture is vulnerable to adversary actions including interference, jamming, directed energy, and antisatellite weapons. Despite the rise in adversary threats, the DoD continues to grow more reliant on SATCOM services in execution of all seven joint warfighting functions. The Marine Corps Operating Concept acknowledges that traditional beyond line-of-sight (BLOS) communications capabilities will be severely degraded or non-existent in the future fight. This research demonstrates a near-term solution that increases resiliency in BLOS communications consisting of a rocket-delivered expeditionary narrowband radio relay with an applicable use case. The payload of the relay consists of a software-defined radio controlled by a single-board computer and demonstrates resiliency by cross-banding signals between very high frequency and ultra high frequency transmit and receive frequencies, respectively. After a rigorous design and test process, this research culminated with an actual demonstration over the air and an attempted delivery by an actual rocket to a target altitude of 30,000 feet.

Within the NPS Small Satellite Lab, research and development of emerging technologies and their implementation as CubeSat payloads has continued to be a focus of hands-on, lab-based academics. Testing of these student-built CubeSats in real-world environmental conditions began with the high-altitude balloon project in which large Nomex weather balloons were used to carry student-built CubeSat payloads to near-space altitudes. Since the inaugural flight in 2011, the high-altitude balloon project has generated interest from both senior civilian and military leadership, as the academic and military utility of such a program is readily apparent. Building upon the success of the program, this thesis seeks to complement the capabilities of the high-altitude balloon as an academic education tool and military payload delivery vehicle through the development of a high-power rocket program within the NPS Space Systems Academic Group. In addition to providing procedures and documentation as to the requirements for establishing a high-power rocket program, this thesis details the design, construction, and proof-of-concept flight of a reusable rocket capable of delivering standard dimension payloads to near-space altitudes. Results from several rocket flights are then used to explore the academic and military utility of a sustainable high-power rocket program.

The configurable fault-tolerant processor (CFTP) project was intended to develop the means for a system to operate in areas which include frequent single-effect events (SEEs) similar to those caused by ionized radiation colliding with logic gates. Such errors are capable of degrading the functionality of a system and completely changing a state machine, such as is at the heart of most spacecrafts’ processors. The method for this consisted of a field-programmable gate array (FPGA) being designed into a system which is capable of detecting and then correcting SEEs. The system was designed by many students. This project will take that design, which launched into space earlier this year, and reduce it to modules which can be uploaded individually, built around a core which will be part of the existing triple fault-tolerant design (TFTD). Modularizing the code allows more experiments to be simultaneously performed in the future by changing the architecture of the system to upload specific modules to specified addresses. This will allow smaller uploads and code tweaks, without incurring long upload times, and more frequent updates to run specific tests ad hoc. Research and development conducted for this thesis has demonstrated the capability to inject configuration errors into the current design and the TFTD’s ability to detect those and similar errors, contributing to a better understanding of the TFTD.

With traditional radio frequency (RF) bands becoming congested and the Department of Defense (DoD) expanding its efforts in the field of small satellites, the need for an on-orbit software-defined radio (SDR) has emerged. SDRs are a compact, off-the-shelf, low-cost, low-risk options for small satellite communication and can provide the flexibility of on-orbit configurability. This study includes the research toward the development of an on-orbit SDR CubeSat payload that can transmit on X-band spectrum (8–12 GHz). This band of interest can provide higher data rates and more bandwidth. Work in CubeSat transmitters and receivers supports development of national capabilities in space of benefit to warfighters. The payload designed, built, and tested for this research is called Com-Cube. Com-Cube utilizes hardware components and software considered for incorporation into a future CubeSat payload. Com-Cube was tested on a low altitude balloon (LAB) flight and demonstrated the transmission of images taken in-flight to a ground station via an amateur radio C-band frequency (5.75 GHz). This work directly supports a transmitter and receiver needed for future telemetry, tracking, and command (TT&C) and payload applications in the field of small satellites. This type of payload provides a test platform for further NPS research in the Mobile CubeSat Command and Control (MC3) ground station network operations and broadcast and receive experiments at frequencies of interest., http://archive.org/details/softwaredefinedr1094561218, Outstanding Thesis, Lieutenant, United States Navy, Approved for public release; distribution is unlimited.

This thesis contributes to the growing body of research concerned with the issue of the increasing numbers of government small satellites (SmallSats) and the limited number of ground stations available to support these missions. To understand this “many satellite, few ground station” problem, a Monte Carlo simulation is used to identify the point at which a single ground station is expected to be overwhelmed, specifically looking at the case of the Mobile CubeSat Command and Control (MC3) ground station at the Naval Postgraduate School (NPS). Ground station saturation is defined in terms of data downlink requirements and the increasing number of conflicting passes as the number of SmallSats grows. An assessment of when one ground station becomes insufficient for a growing number of SmallSats is the result. The MATLAB software tools created to generate these scenarios are generic and can be used to extend this work to investigate other scenarios of SmallSats and multiple ground stations.

The current ground station infrastructure of the Naval Postgraduate School (NPS) Mobile CubeSat Command and Control (MC3) Network can sufficiently manage the existing three CubeSats that it has been tasked to monitor and control. However, the projected growth in the quantity of these satellites will produce greater likelihood of conflicting passes, a condition where multiple CubeSats are above the horizon simultaneously with respect to a single ground station and are competing for limited downlink antenna assets. Consequently, as more CubeSats are placed in orbit, the ground stations that communicate with them need to become more efficient and require optimization strategies to make best use of the network. Using the MC3 historical data set for its PropCube satellites, this thesis creates a grading scale that can be used to prioritize which PropCube should have antenna priority based on the expectation of downlinking data and when during the satellite’s pass an operator should expect to capture that data. This value function can be used by an optimization program, such as that being developed in the NPS Small Satellite Laboratory, to maximize the data retrieved from a constellation of satellites. Additionally, the tools developed for analyzing and understanding MC3 PropCube passes can be used to determine value functions for other ground station networks in order to efficiently schedule CubeSat contacts.

This thesis builds on the existing research of the Sensor Research Laboratory and the Space Systems Academic Group (SSAG) at the Naval Postgraduate School (NPS) to integrate an 80-micron terahertz (THz) imaging camera (TIC) as a CubeSat payload. This research investigates the potential utility of THz imaging and long-wave infrared (IR) imaging at room-temperature (20°C) cooling for applications of national interest like space situational awareness (SSA). Long-wave IR imaging capability already exists, and typically requires a large cryocooler to maintain cryogenic temperatures (3–70 K); efficient IR imaging at room temperature is an emerging technology. Additionally, this thesis examines the integration and test effort associated with flight qualifying the TIC engineering development unit (EDU) onto the SSAG-developed High Altitude Balloon (HAB) bus. This thesis contributes to the overall objective of integrating and flight qualifying the TIC as a payload compatible with a variety of buses. Integrating and testing the TIC EDU on a CubeSat attains focused research objectives of national interest and supports Department of Defense Space efforts in the utilization of very small satellites.

Electromagnetic (EM) spectrum management is an escalating concern in today’s growing wireless market, and ensuring that the growing number of EM spectrum users have adequate access will become only harder and more expensive as the number of users of cellular phones and satellite operations continues to grow. Utilizing and effectively sharing available spectrum is an involved process with many users competing for access. With the ever-increasing demand for EM spectrum, the creation and utilization of policies and regulations that support and encourage the co-utilization of EM spectrum bands is of growing importance. The Mobile CubeSat Command and Control (MC3) ground station personnel at the Naval Postgraduate School (NPS) in Monterey, California, conducted a series of tests with local news station KION to determine the feasibility of simultaneously using an S-Band uplink frequency to conduct telemetry, tracking, and communications (TT&C) with NPS CubeSats while KION conducted its electronic news gathering (ENG) operations. The testing determined that conducting TT&C satellite operations above 7 degrees of antenna elevation does not impact ENG operations in Monterey. Our results may encourage spectrum co-utilization and ease the strain on the increasingly congested EM spectrum.

A satellite to be used as a testbed for experiments such as the Configurable Fault Tolerant Processor (CFTP) was designed at the Naval Postgraduate School. This processor consists of a Field Programmable Gate Array (FPGA), which may be reprogrammed by receiving a signal from a source external to the satellite. Experimentation of a high-speed pipelined and fault tolerant Fast Fourier Transform (FFT) was conducted for use within the CFTP. In this thesis, we detail the development and testing of a high-speed pipelined FFT in which fault tolerance can be applied at a later opportunity. Xilinx Vivado ISE® was utilized to synthesize behavioral Verilog to program an FPGA. Xilinx Vivado ISE’s® simulation suite produced waveforms to demonstrate functionality. Launch of CFTP is planned for FY18 aboard NPSat-1.

To address the growing population of small satellite constellations that rely on distributed ground station networks, a dynamic optimization problem is formulated and solved. Specifically, this dissertation addresses the problem formulation, algorithm implementation, and experimental techniques developed to optimally slew ground-based antennas between multiple satellites that are simultaneously in view of one or more earth stations. The problem is solved using DIDO, a MATLAB optimal control solver, to produce deconflicted ground antenna slew trajectories. The deconfliction parameters include space-to-ground link budgets, mission priority, asset availability, and onboard health. Traditional methods employ heuristics to generate a subset of available targets and a separate process to check feasibility of the solution. The method described in this dissertation deterministically solves the problem in a single step. The approach is experimentally validated and tested using a small constellation of low-Earth-orbiting CubeSats operated by the Small Satellite Laboratory at the Naval Postgraduate School, using the Mobile CubeSat Command and Control (MC3) ground station network., http://archive.org/details/resourceconstrai1094560435, Civilian, Department of the Navy, Approved for public release; distribution is unlimited.

In the next few years, the Space Systems Academic Group (SSAG) and the Small Satellite Laboratory at the Naval Postgraduate School (NPS) may begin work on a small satellite swarm constellation. This thesis introduces flight operations concepts for small satellite formations conducting sparse aperture radar missions to inform decision makers at NPS of possible flight operations options. An orbital modeling program called Systems Tool Kit was used to simulate combinations of flight patterns and orbits, including a pendulum and a helix inline hybrid model, and a cartwheel hybrid model. The MATLAB software package was used to plot the simulated orbits, calculating the flight formation stability, and for calculating the relative effects of sensor separation on the system resolution. Findings include a stable dispersion pattern for the satellites to conduct their mission and an ability to maintain safe, collision-free flight operations.

With traditional radio frequency (RF) bands becoming congested and the Department of Defense (DoD) expanding its efforts in the field of small satellites, the need for an on-orbit software-defined radio (SDR) has emerged. SDRs are a compact, off-the-shelf, low-cost, low-risk options for small satellite communication and can provide the flexibility of on-orbit configurability. This study includes the research toward the development of an on-orbit SDR CubeSat payload that can transmit on X-band spectrum (8–12 GHz). This band of interest can provide higher data rates and more bandwidth. Work in CubeSat transmitters and receivers supports development of national capabilities in space of benefit to warfighters. The payload designed, built, and tested for this research is called Com-Cube. Com-Cube utilizes hardware components and software considered for incorporation into a future CubeSat payload. Com-Cube was tested on a low altitude balloon (LAB) flight and demonstrated the transmission of images taken in-flight to a ground station via an amateur radio C-band frequency (5.75 GHz). This work directly supports a transmitter and receiver needed for future telemetry, tracking, and command (TT&C) and payload applications in the field of small satellites. This type of payload provides a test platform for further NPS research in the Mobile CubeSat Command and Control (MC3) ground station network operations and broadcast and receive experiments at frequencies of interest.

Space is a harsh environment, full of high-energy radiation that can cause single-event effects (SEE) in orbiting satellites. Some of these effects, such as single-event upsets and single-event functional interrupts, occur when ionizing radiation causes the logical value in a memory element to change and are detectable and correctable through various error mitigation techniques. In this thesis, we develop and implement a hardware solution to combat these SEE for deployment as an experimental module on Naval Postgraduate School Satellite 1 (NPSAT-1). Based on the relatively benign orbit of NPSAT-1, industrial-grade, commercial-off-the-shelf components that have shown tolerance to radiation were selected to keep costs low. The primary source of mitigation relies on a globally triple-modular redundant microprocessor system instantiated inside of a XILINX Kintex-7 field-programmable gate array. The system consists of an open-source microprocessor without interlocked pipeline stages (MIPS) based processor softcore, a cached memory structure capable of accessing double-data rate type three and secure digital card memories, an interface to the main satellite bus, and XILINX’s soft error mitigation softcore. The hardware was tested both in and out of the system and verified to work on the ground with faults injected. Other techniques to mitigate errors due to SEE, such as memory scrubbing, are intended to be added before launch.

Dr. Appleget earned his NPS Operations Research Ph.D. in 1997 and joined his alma mater as a Senior Lecturer in 2009 after retiring from the Army at the rank of colonel. His impressive interdisciplinary accomplishments at NPS include co-directorship of the Human, Social, Culture, and Behavior Modeling Program involving students and faculty from multiple departments and academic groups. He is also the coordinator of the Joint Warfare Analysis Center Research Program. His interdisciplinary teaching activities are evident in the cross-campus design and delivery of courses in Wargaming Applications and Modeling and Simulation of Societies in Conflict.

Hamming Interdisciplinary Achievement Award Recognition Announcement

Force-limited vibration testing (FLVT) is effective in reducing the low-frequency vibration test environment for CubeSats on the Naval Postgraduate School CubeSat Launcher (NPSCuL); however, the CubeSats are still subjected to high-frequency amplifications above 500 Hz from the NPSCuL structure. The excessive, high-frequency vibration has caused test failures and forces CubeSat developers to focus more on surviving environmental testing instead of developing state-of-the-art technology. Whole-spacecraft isolation systems are often used to reduce these amplifications, but they currently exist only for large spacecraft and are too expensive to adapt for small satellites. These limitations motivated the combined use of FLVT and commercial-off-the-shelf (COTS) isolators on NPSCuL as a novel, practical, and low-cost method to reduce vibration levels for small satellites. This method significantly reduces the high-frequency amplification by up to 97%; the root-mean-square acceleration (GRMS) over the entire test frequency range drops by up to 78%. These results should allow more sensitive and complex payloads to gain access to space on future NPSCuL missions and demonstrate how a worst-case environment on a small satellite can be improved. Implementing low-cost, COTS isolators on other small satellites and CubeSat launch applications could be useful as well.

The Operationally Unique Technologies Satellite (OUTSat), the Government Experimental Multi-Satellite (GEMSat), and the Unique Lightweight Technology and Research Auxiliary Satellite (ULTRASat) missions, launched in 2012, 2013, and May 2015, successfully deployed a total of 33 CubeSats from Poly-Picosatellite Orbital Deployers (P-PODS) mounted to the Naval Postgraduate School (NPS) CubeSat Launcher (NPSCuL) on the aft end of the Atlas V Centaur upper stage. An additional 13 CubeSats are scheduled to launch on the Government Rideshare Advanced Concepts Experiment (GRACE) in September 2015. Force-limited vibration testing (FLVT) has been effective on all four missions in reducing the low-frequency vibration test environment at the P-POD interface on NPSCuL; however, the CubeSats were still subjected to high-frequency amplifications from the NPSCuL structure. Implementing commercial-off-the-shelf (COTS) isolators at the base of the NPSCuL structure has recently been shown to significantly reduce the high-frequency amplifications. This paper discusses the testing and the resulting 35-85% drop in overall G(RMS) vibration test levels, a welcome reduction in the CubeSat vibration test envirionment on NPSCuL. This reduction should allow more sensitive payloads to fly on future NPSCuL missions, and the implementation of low-cost, COTS isolators could possibly be useful for other small satellites and CubeSat launch applications.

The Naval Postgraduate School CubeSat Launcher (NPSCuL) is a five-sided structure capable of carrying up to 24 CubeSats to orbit. The vibration test environment for CubeSats flying on NPSCuL on the Atlas-V is extremely harsh, partly due to the input vibration environment from the launch vehicle itself, and partly due to amplification from the NPSCuL structure. This thesis documents the implementation of a relatively new technology, Force Limited Vibration Testing (FLVT), and the design of a stiffer structure to reduce the vibration environment for NPSCuL payloads. Most acceleration-controlled vibration tests result in significant over-test. FLVT limits shaker forces, producing more realistic tests and potentially provides relief to payloads. Additionally, increasing the stiffness of NPSCuL using an isogrid design, aimed to increase its first-fundamental frequency, could result in less displacement at higher frequencies for a given amount of input energy, possibly improving the payload vibration environment. It was found that FLVT was very successful in reducing vibration environments for NPSCuL payloads. Although redesigning NPSCuL using an isogrid design achieved the goal of increasing system stiffness, it did not reduce the vibration environment. None the less, lessons learned from the redesign process will be valuable for continuing vibration environment reduction efforts.

The Naval Postgraduate School Solar Cell Array Tester (NPS-SCAT) is the first CubeSat for the Naval Postgraduate School (NPS). The NPS-SCAT mission was designed to measure solar cell performance degradation in low earth orbit. NPS-SCAT serves as a pathfinder for future NPS CubeSat missions. This thesis documents the pre-flight NPS-SCAT battery analysis, power budget, vibration analysis, beacon antenna integration evaluation, and conformal coat study. Some data from the flight is presented, which validates the pre-flight power budget analysis.

The Mobile CubeSat Command and Control (MC3) architecture is a growing network of ground stations that spans the United States of America. It was designed to support the National Reconnaissance Office’s Experimental CubeSat Program. Each node was originally designed to communicate via UHF and S-band frequencies using Yagi antenna only. The MC3 ground station at the Naval Postgraduate School has recently incorporated a 3-meter S-band dish. This thesis documents the calibration and capabilities of the new S-band dish. It also investigates the possibility of using the antenna outside of its normal operating range. In particular, the idea of using an S-band, 3-meter dish to receive UHF band signals was tested by designing a UHF signal feed optimized for 915 MHz and used to listen to a UHF source deployed on a high altitude balloon at near orbital distances. In addition, this document discusses the integration of a dish system into current and future MC3 ground stations.

The purpose of this thesis is to design and test a fault–tolerant reduced instruction set computer processor running a subset of the multiprocessor without interlocked pipelined stages instruction set. This processor is implemented on a field programmable gate array (FPGA) and will be used as the foundation for a payload processor on a cube satellite developed at the Naval Postgraduate School. This thesis begins by considering the radiation effects present in the space environment and the various fault– tolerant designs used to guard against specific types of particle events. The internal triple modular redundancy method is selected and implemented at each pipeline stage of the processor. Next, a target FPGA is selected based on the performance requirements of the processor. The Virtex–5 (registered trademark of Xilinx, Inc.) is selected over the ProASIC3 (registered trademark of Microsemi, Inc.) due to its enhanced capabilities and potential to support expansion for future applications. The hardware design is presented as a hybrid Verilog and schematic based design. The system consists of the processor and a universal asynchronous receiver/transmitter that reads and writes data received from a generic serial interface. The device is simulated to ensure proper logic functionality. Conclusions and future work are discussed.

A versatile and heretofore unutilized coupling is obtained by press-fitting a hollow nickel titanium shape memory alloy (SMA) shaft into a steel hub. This produces an SMA interference coupling that is distinct from other SMA actuators by the method in which the SMA is used. Press-fitting the hollow SMA shaft in its detwinned martensitic phase into a steel hub creates a joint capable of holding parts such as emergency doors, satellite solar panels, or tamper locks securely together until commanded release. Release is accomplished by heating the SMA to its activation temperature. The resulting decrease in diameter of the hollow SMA shaft allows it to easily slip out of the hub, releasing the part. Load testing of the SMA interference coupling showed ultimate strengths about twice that of traditional press-fit coupling strength calculations. The coupling can be designed to be a simple mechanism of very small size, on the order of one cubic centimeter, capable of achieving coupling strengths in excess of 4000 N (900 lbf).

The design of a device that controls the sequence and timing of deployment of CubeSats on the Naval Postgraduate Schools CubeSat Launcher (NPSCuL) is detailed in this thesis. This design is intended to be implemented on a field-programmable gate array (FPGA) installed into the NPSCuL. This configuration allows flexibility in reprogramming the launch sequence and adding additional functionality in future designs. Operating an FPGA on orbit presents unique challenges due to the radiation environment. Radiation from space cannot be shielded efficiently, so devices must be tolerant of the expected effects. The most common effect, the single-event upset can have detrimental effects on operating electronics, causing undesired changes to data. To combat this problem, fault tolerant techniques, such as triple-modular redundancy (TMR) are explored. In these methods, multiple redundant copies of the design are operated simultaneously, and the outputs are voted on by special circuits to eliminate errors. Comparisons between manual and software generated TMR methods are tested, and the design is implemented on test hardware for further verification. Finally, future research and testing is discussed to continue to ready the design for employment of the sequencer on an actual space mission.

This thesis concerns various means of implementing fault tolerance in logic for use in a general payload processor design. The first specific application of this research is a sequencer developed for deploying CubeSats. The sequencer shall be capable of the timing and accurate deployment of multiple CubeSats from a host spacecraft and shall have the capability for quick reconfiguration prior to launch. This research considers a variety of hardware for suitability toward sequencer construction; field programmable gate arrays (FPGAs) are chosen as the primary device. The design further evolves to selection of the Actel ProASIC3 series of FPGAs. Initial logic test configurations are implemented on a development kit with analysis of results provided. Fault-tolerant techniques are compared with a set of experiments to determine optimum resource utilization and timing schemes. Triple modular redundancy (TMR) is selected as the technique for fault-tolerant logic implementation in the sequencer. Preliminary test boards are built via schematic design and printed circuit board layout. The manufacturing, integration and testing of the ProASIC3 Test Board is fully discussed. A follow-on flight prototype board is designed with more extensive hardware allowing for implementation of fault-tolerant techniques and future growth capability. Recommendations for future work are discussed.

Worldview-2 spectral imagery acquired over Duck, NC and Pendleton, CA were analyzed to extract Bidirectional Reflectance Distribution Functions (BRDF) for 8 spectral bands. Spectral data in the visible and near-infrared bands were acquired for 15 azimuth/elevation values during the Duck NC orbit pass; data were collected at ten-second intervals. Ten images were acquired over Pendleton. Orthoready images were coregistered using first-order polynomials for the two image sequences. BRDF profiles have been created for scene elements: vegetation, asphalt, sand, and water. These data allowed for unique high-spatial resolution BRDF profiles, which can be used to inform terrain classification and target detection in satellite imagery., http://archive.org/details/highspatialresol109455102, US Navy (USN) author, Approved for public release; distribution is unlimited.

The NPSAT1 project is a Naval Postgraduate School (NPS) educational small satellite combining student education in satellite systems and operations, institutional research, and sponsored experiments with the objective of testing technologies for applications in space flight. The micro-electro-mechanical system (MEMS) rate sensor is one of these experimental technologies. Packaging three of these MEMS sensors together makes a 3-axis rate sensor suite. The MEMS experiment was originally conceived of as a low-cost, low-mass augmentation to the magnetometer for use by the Attitude Control System (ACS). The experiment is to test the sensor suite's ability to measure NPSAT1 rates, comparing these rates to those determined by using a magnetometer and GPS. Operationally, the goal is to perform a space-flight demonstration of the MEMS sensor. This thesis includes two phases of research and development. First, the MEMS 3- axis rate sensor suite is fully tested and characterized. Experimental testing proves the sensor suite's effectiveness as a low-cost, low-mass augmentation to the magnetometer for satellite rate determination, as well as its ability to measure very low rates. Second, we adapt the original design and operations to maximize the accuracy and utility of the sensor suite. Finally, a complete flight-like subsystem is built and tested., http://archive.org/details/characterization109453246, US Army (USA) author., Approved for public release; distribution is unlimited.

The Naval Postgraduate School's first CubeSat, the NPS Solar Cell Array Tester (NPS-SCAT), demonstrates the capability of the CubeSat form factor as a technology test bed by implementing a single experiment--a solar cell tester. The need to validate solar cell performance on orbit, in the harsh space environment, is recurring with the continued development of advanced, untested solar cells. By using a relatively inexpensive platform, the CubeSat, such solar cells can be tested and the risk for larger satellites mitigated with this experiment. This thesis discusses the design and construction process of the solar cell array tester payload along with its integration with the remaining satellite subsystems (command and data handling subsystem, communications subsystem, and electrical power subsystem) including the problems encountered along the way and the chosen solutions. In addition, the systems engineering and testing procedures developed for and conducted on the satellite engineering design unit will be described in detail., http://archive.org/details/npsscatsystemsen109455283, US Navy (USN) author, Approved for public release; distribution is unlimited.

This thesis contains the results of a complete redesign effort, including development, integration, and experimental testing of a very small mechanical coupling mechanism. This mechanism is suitable for nano-satellites and uses a shape memory alloy (SMA) ring, press-fit into a metallic bushing to create a releasable interference joint. A detailed explanation of the techniques used to press-fit the SMA ring into the metallic bushing is included along with a description of why the SMA ring shrinks to its austenite phase upon heat activation and how it decouples from the metallic bushing. The couplingengineered to be as small as one tenth of a cubic centimeteris capable of achieving holding strengths in excess of 135 N (30 lbf). SMA characteristics and current release mechanisms are explained and tests are conducted to validate the holding strength achieved by the interference joint between the SMA and the metallic bushing. The design and part selection for each component of the Engineering Design Unit (EDU) is documented and launch conditions simulated to test the EDUs performance, releasability, and to validate the static holding force. Finally, this thesis describes the simulated integration of the EDU into a 3U CubeSat structure.

Solar cells are the primary energy-collection agents used onboard spacecraft converting energy from the sun into electricity. With solar cells being the main source of power for satellites, it is important to know how they operate and degrade when exposed to the harsh environment of low earth orbit. The objective of this thesis is to estimate the solar cell degradation that will be experienced on orbit due to radiation. This linked with the mission of the NPS-SCAT providing a quantitative measurement on orbit of how solar cells degrade over time can reduce risk of expensive national satellite by providing real-life solar cells exposure to threats of the space environment. A secondary goal of this thesis is to build and present a representation of the CONOPs (concept of operations) that describes the functionality expected on orbit. Coordination with the software programmers as well as the staff to set robust functionality is the goal for the CONOPs. This software package will be programmed into the two 1U flight certified CubeSats as their standard programming once implementation and testing have been completed.

The Sensor Research Lab at the Naval Postgraduate School is developing a real-time THz imaging camera. Vital to its design is the metamaterial absorbing layer (metafilm) within each pixel that allows for THz absorption. While there are numerous applications in the THz region, sensors and sources for THz energy have much room for improvement. The use of metamaterial technology for the purpose of a THz sensor has the potential to reduce costs while greatly improving sensitivity performance. The Sensor Research Lab has fabricated metafilms capable of near 100 percent absorption. In this research project, absorption characteristics of a set of metamaterials were measured using Fourier transform THz spectroscopy and modeled using an RLC circuit. The model provides a good description of the absorption characteristics and should assist in better understanding of the electromagnetic interactions within the metafilm.