Geolocation of source interference from a single satellite with multiple antennas

Interference of satellite communications is a frequent and ongoing concern for both DoD and civilian enterprises. Geolocation of the interfering source is an essential step in mitigating or eliminating the interference and restoring operation of the communications service. Existing techniques to locate sources of such interference are not applicable to newer satellite communications systems. This thesis offers an innovative method for locating interference that takes advantage of modern multi-antenna satellites. The location of a source of radio frequency interference can be determined by comparing the received signal strength across multiple antennas on the same satellite. The difference between signal strength'as received by the satellite antennas'can be computed and plotted as lines of position on the surface of the Earth. The intersection of two or more lines of position represents the location of the interfering transmitter. An advantage of this method is that it is completely passive and can be done in real time. The size and accuracy of the resultant geolocation area are a function of a number of different factors, including terrestrial latitude of the interfering transmitter, the accuracy of the signal strength measurement, and the geometry of the intersecting lines of position.http://archive.org/details/geolocationofsou1094541379Lieutenant Commander, United States NavyApproved for public release; distribution is unlimited

Debating Space Security: Capabilities and Vulnerabilities

The U.S. position in the debate on space security has been that (1) space-based systems could be developed and used to obtain decisive warghting superiority over an adversary, and (2) these space-based systems, because they might give such an inordinate advantage over any adversary, will be attacked. The Russians and Chinese, in contrast, claim to be threatened by U.S. aspirations in space but deny that they pose a serious threat to U.S. space-based systems. They view the development of advanced military space systems by the United States as evidence of a growing gap of military capabilities limited only by technological--not political--constraints. They argue that U.S. missile defense systems operating in coordination with advanced satellite sensors would weaken their nuclear retaliatory potential. This dissertation argues that the positions held by both of these parties are more extreme than warranted. An analytical evaluation quickly narrows the touted capabilities and assumed vulnerabilities of space systems to a much smaller set of concerns that can be addressed by collaboration. Chapter 2: Operationally Responsive Space (ORS): Is 24/7 Warghter Support Feasible? demonstrates the infeasibility of dramatically increasing U.S. warfighting superiority by using satellites. Chapter 3: What Can be Achieved by Attacking Satellites? makes the case that although U.S. armed forces rely extensively on its satellite infrastructure, that does not immediately make them desirable targets. The functions performed by military satellites are diffused among large constellations with redundancies. Also, some of the functions performed by these satellites can be substituted for by other terrestrial and aerial systems. Chapter 4: The Limits of Chinese Anti-Satellite Missiles demonstrates that anti-satellite (ASAT) intercepts are very complex under realistic conditions and that a potential adversary with space capabilities comparable to China's has very limited capability to use ASATs in a real-world battle scenario. Finally, in order to evaluate the chief concern raised by the Russians and Chinese, chapter 5: Satellites, Missile Defense and Space Security simulates a boost-phase missile defense system cued by the advanced Space Tracking and Surveillance (STSS) sensors. It demonstrates that even under best case assumptions, the STSS sensors are not good enough for the boost-phase missile defense system to successfully intercept and destroy an ICBM. Together, these chapters aim to narrow the contentions in the debate on space security thereby fostering the international colloboration and data sharing needed to ensure safe operations in space

A cost-effectiveness analysis of tactical satellites, high-altitude long-endurance airships, and high and medium altitude unmanned aerial systems for ISR and communication missions

Before 1991, the United States military's demand for additional communications bandwidth and timely intelligence was rising rapidly. Since then, with the advent of the Global War on Terrorism, it has increased substantially. To address this growing need, the Department of Defense has focused its acquisition and procurement efforts on obtaining new communications and intelligence, surveillance, and reconnaissance (ISR) platforms that can help lessen shortfalls and possibly exploit new, untapped resources. Recently, there has been an increasing focus on new technology, such as tactical satellites or high-altitude long-endurance airships, as a way to increase communications and intelligence collection capacities. Likewise, advances in the capabilities of medium-altitude and high-altitude unmanned aerial systems have resulted in a more prominent role for them on today's battlefield. Each of these vehicles has a unique niche in today's military, but the increasing capabilities of each are beginning to create some overlap in their uses. This study will conduct a cost-effectiveness analysis on these systems for use as a persistent communications and ISR platform. In particular, it will measure the effectiveness of each for comparison, and will offer possibilities to increase the overall effective use of the three together to maximize performance and cost.http://archive.org/details/acosteffectivene109453934US Army (USA) author.Approved for public release; distribution is unlimited

Tactical Satellite (TacSat) feasibility study a scenario driven approach

The objective of this project was to examine the feasibility of developing a tactically controlled, operationally responsive satellite system. A specific mission scenario, the Philippine Sea Scenario, was chosen to guide and bound the analysis. Within the bounds of this scenario, this high level space systems engineering exercise provided insights into operations and military utility as well as enough granularity to estimate costs for such a system. The operational approach and high level design concept is based on the Space Mission Analysis and Design (SMAD) process authored by Wiley J. Larson and Kames R. Wertz. The study shows that there are tactical scenarios in which space capabilities provide military utility and cost effectiveness above what is provided by traditional tactical assets such as UAVs. This is particularly true when large operational areas are involved and long periods of service are required.http://archive.org/details/tacticalsatellit109456927N

Defense Acquisitions: Assessments of Selected Weapon Programs

A letter report issued by the Government Accountability Office with an abstract that begins "This is GAO's ninth annual assessment of Department of Defense (DOD) weapon system acquisitions, an area that is on GAO's high-risk list. The report is in response to the mandate in the joint explanatory statement to the DOD Appropriations Act, 2009. It includes observations on the performance of DOD's 2010 portfolio of 98 major defense acquisition programs; data on selected factors that can affect program outcomes; an assessment of the knowledge attained by key junctures in the acquisition process for a subset of 40 programs, which were selected because they were in development or early production; and observations on the implementation of acquisition reforms. To conduct this review, GAO analyzed cost, schedule, and quantity data from DOD's Selected Acquisition Reports and collected data from program offices on performance requirements and software development; technology, design, and manufacturing knowledge; and the implementation of DOD's acquisition policy and acquisition reforms. GAO also compiled one- or two-page assessments of 71 weapon programs. These programs were selected based on their cost, stage in the acquisition process, and congressional interest. DOD disagreed with GAO's use of total program cost growth as a performance metric because it includes costs associated with capability upgrades and quantity increases. GAO believes it remains a meaningful metric and that the report explicitly accounts for the cost effect of quantity changes.

Exploring bistatic scattering modeling for land surface applications using radio spectrum recycling in the Signal of Opportunity Coherent Bistatic Simulator

The potential for high spatio-temporal resolution microwave measurements has urged the adoption of the signals of opportunity (SoOp) passive radar technique for use in remote sensing. Recent trends in particular target highly complex remote sensing problems such as root-zone soil moisture and snow water equivalent. This dissertation explores the continued open-sourcing of the SoOp coherent bistatic scattering model (SCoBi) and its use in soil moisture sensing applications. Starting from ground-based applications, the feasibility of root-zone soil moisture remote sensing is assessed using available SoOp resources below L-band. A modularized, spaceborne model is then developed to simulate land-surface scattering and delay-Doppler maps over the available spectrum of SoOp resources. The simulation tools are intended to provide insights for future spaceborne modeling pursuits

Report on active and planned spacecraft and experiments

Information is presented, concerning active and planned spacecraft and experiments known to the National Space Science Data Center. The information included a wide range of disciplines: astronomy, earth sciences, meteorology, planetary sciences, aeronomy, particles and fields, solar physics, life sciences, and material sciences. These spacecraft projects represented the efforts and funding of individual countries as well as cooperative arrangements among different countries

Information retrieval from spaceborne GNSS Reflectometry observations using physics- and learning-based techniques

This dissertation proposes a learning-based, physics-aware soil moisture (SM) retrieval algorithm for NASA’s Cyclone Global Navigation Satellite System (CYGNSS) mission. The proposed methodology has been built upon the literature review, analyses, and findings from a number of published studies throughout the dissertation research. Namely, a Sig- nals of Opportunity Coherent Bistatic scattering model (SCoBi) has been first developed at MSU and then its simulator has been open-sourced. Simulated GNSS-Reflectometry (GNSS-R) analyses have been conducted by using SCoBi. Significant findings have been noted such that (1) Although the dominance of either the coherent reflections or incoher- ent scattering over land is a debate, we demonstrated that coherent reflections are stronger for flat and smooth surfaces covered by low-to-moderate vegetation canopy; (2) The influ- ence of several land geophysical parameters such as SM, vegetation water content (VWC), and surface roughness on the bistatic reflectivity was quantified, the dynamic ranges of reflectivity changes due to SM and VWC are much higher than the changes due to the surface roughness. Such findings of these analyses, combined with a comprehensive lit- erature survey, have led to the present inversion algorithm: Physics- and learning-based retrieval of soil moisture information from space-borne GNSS-R measurements that are taken by NASA’s CYGNSS mission. The study is the first work that proposes a machine learning-based, non-parametric, and non-linear regression algorithm for CYGNSS-based soil moisture estimation. The results over point-scale soil moisture observations demon- strate promising performance for applicability to large scales. Potential future work will be extension of the methodology to global scales by training the model with larger and diverse data sets

A Search for the Origin of Ultra-High Energy Neutrinos with ANITA-4

The ANtarctic Impulsive Transient Antenna (ANITA) aims to detect Askaryan radio signatures from ultra-high energy (UHE) neutrinos interacting with the Antarctic ice sheet. However, the origin of neutrinos of such high energies is mostly unknown. This thesis contains a method for finding the potential astrophysical origin of UHE neutrinos, and includes the simulation and analysis used throughout the source search. The thesis also discusses the essential physics, the components of the experiment, and the details of the fourth flight of the ANITA experiment, ANITA-4. Though the source search itself was conducted for this specific flight, the methods presented can be applied to any previous or future flights. As such experiments are not yet sensitive enough to obtain a large dataset of UHE neutrinos, the sub-threshold events detected by ANITA-4 were projected back to the sky. The spatiotemporal proximity of such events were compared to the activity of several objects. Three classes of objects were studied: blazars, gamma-ray bursts (GRBs), and supernovae (SNe). A single object, the flaring blazar known as PKS 1502+106, showed an excess of events pointing back to it, exceeding the 99% confidence level threshold. Such searches and analyses are not yet sensitive enough to detect a high number of ultra-high energy neutrinos, and thus cannot directly point them back to their potential astrophysical origins. However, the sub-threshold analysis conducted in this thesis motivates future source search investigations, especially with the increase in sensitivity of upcoming experiments

Space Security 2008

Provides data and analysis on space activities in 2007 and their cumulative impact on security issues, including space laws, policies, and doctrines; civil space programs and global utilities; commercial uses; and environmental and military issues