Joint Unmanned Combat Air System Matching Mission Requirements, Performance Capabilities, and Critical Aviation Systems

The Joint Unmanned Combat Air Systems (J-UCAS) acquisition program is a joint Air Force and Navy effort led by the Defense Advanced Research Projects Agency (DARPA) to demonstrate a networked system of unmanned combat air vehicles (UCAV) to effectively and affordably prosecute 21st century combat missions. The potential of these weapon systems to perform dangerous combat missions at a relatively low-cost and low-risk has garnered significant interest from both Congress and the Department of Defense (DoD) and raised expectations that the J-UCAS will replace some of the DoD’s aging tactical aircraft fleet. This paper will address the requirement for the DoD and Armed Services to collectively resolve a new vision and clear strategy for the integration of unmanned combat air vehicles into the Armed Forces and the future battlespace. The DoD and Armed Services continue to struggle among themselves and with defense contractors to match resources and requirements in the development of individual “service-centric” UCAVs for specific mission areas. The current vision and strategy of the J-UCAS program is derived from an initial assessment of the cost and risk benefits of UCAV development. The failure of this approach is that it will not yield a UCAV with a distinct strategic and operational advantage. This research will trace the evolution of the current J-UCAS acquisition program. A systems-engineering approach will be applied to a reassessment of the desired J-UCAS mission requirements and corresponding performance capabilities that will serve to guide the development of critical aviation systems in the context of current and emerging technologies. It was concluded that while the J-UCAS program should remain a joint effort, the United States Air Force (USAF) should be given the priority on developing and fielding the first operational joint UCAV weapon system. Future J-UCAS weapon systems should be designed to operate in a joint environment within the emerging global command and control architecture in coordination with manned aircraft. The J-UCAS must be designed with flexible, multi-mission capability to include intelligence, surveillance, and reconnaissance; suppression of enemy air defenses and strike. The other armed services should support this effort, but initially limit their contributions to evaluating technology demonstrators that primarily focus on interoperability in each of their respective combat environments until such time as the first operational UCAV program has successfully proven its combat effectiveness

LunaNet: a Flexible and Extensible Lunar Exploration Communications and Navigation Infrastructure

NASA has set the ambitious goal of establishing a sustainable human presence on the Moon. Diverse commercial and international partners are engaged in this effort to catalyze scientific discovery, lunar resource utilization and economic development on both the Earth and at the Moon. Lunar development will serve as a critical proving ground for deeper exploration into the solar system. Space communications and navigation infrastructure will play an integral part in realizing this goal. This paper provides a high-level description of an extensible and scalable lunar communications and navigation architecture, known as LunaNet. LunaNet is a services network to enable lunar operations. Three LunaNet service types are defined: networking services, position, navigation and timing services, and science utilization services. The LunaNet architecture encompasses a wide variety of topology implementations, including surface and orbiting provider nodes. In this paper several systems engineering considerations within the service architecture are highlighted. Additionally, several alternative LunaNet instantiations are presented. Extensibility of the LunaNet architecture to the solar system internet is discussed

Radio Frequency Interference Impact Assessment on Global Navigation Satellite Systems

The Institute for the Protection and Security of the Citizen of the EC Joint Research Centre (IPSC-JRC) has been mandated to perform a study on the Radio Frequency (RF) threat against telecommunications and ICT control systems. This study is divided into two parts. The rst part concerns the assessment of high energy radio frequency (HERF) threats, where the focus is on the generation of electromagnetic pulses (EMP), the development of corresponding devices and the possible impact on ICT and power distribution systems. The second part of the study concerns radio frequency interference (RFI) with regard to global navigation satellite systems (GNSS). This document contributes to the second part and contains a detailed literature study disclosing the weaknesses of GNSS systems. Whereas the HERF analysis only concerns intentional interference issues, this study on GNSS also takes into account unintentional interference, enlarging the spectrum of plausible interference scenarios.JRC.DG.G.6-Security technology assessmen

Integration of the Control Display Navigation Unit (CDNU) Into the EA-6B Block 89A Aircraft and its Impact on Navigation Operations

This thesis was to evaluate the attributes of the recent modification and installation of the Control Display Navigation Unit (CDNU) into the EA-6B aircraft. The author conducted multiple ground and flight test events during a three year evaluation of the EA-6B Block 89A aircraft. The Block 89A modification included an embedded Global Positioning System (GPS)/ Inertial Navigation System (INS) (EGI), enhanced functionality with the recent GPS system modification, and the ability to control the navigation, weapon, and communication on one control panel. This modification was an attempt to replace a failing attitude system and also allow for additional capability. The testing performed included ILS and GPS approaches, holding, air navigation routes, low level military navigation routes, and tactical navigation. The EA-6B is currently not authorized to navigate with the GPS as the sole navigation (NAV) nor authorized to conduct GPS approaches. This evaluation revealed a need for a GPS navigation and approach authorization in the EA-6B. Funding should be started immediately to anticipate meeting the technology requirements once free flight is authorized in the US. This thesis describes the navigation modes currently used in the EA-6B aircraft. The newest 89A upgrade demonstrates great advances in navigation ability with the addition of the EGI. The CDNU as installed in the EA-6B Block 89A aircraft satisfies the FAA requirements of a flight management system (FMS). The CDNU also partially satisfies GPS certification requirements for both the FAA and DOD. The requirement necessary to certify and utilize GPS as a primary navigation source to operate in the NAS not including approaches are RAIM or RAIM equivalent. The CDNU has a function known as EHE that uses an algorithm that was shown to be accurate enough to satisfy this requirement as long as it was used in the blended mode of operation. GPS accuracy was excellent and pilot displays were easy to read and follow. The capability to execute non-precision approaches were demonstrated in the testing and with the addition of RAIM, an unalterable loadable approach, and an alert within the pilot’s primary field of view will allow GPS non-precision approach certification. RAIM capability is available with the GEM IV receivers. An unalterable approach is available with the addition of more memory in the CDNU. An alert is available by physically mounting a new warning light or by activating something on the EFIS displays

Survey of Inter-satellite Communication for Small Satellite Systems: Physical Layer to Network Layer View

Small satellite systems enable whole new class of missions for navigation, communications, remote sensing and scientific research for both civilian and military purposes. As individual spacecraft are limited by the size, mass and power constraints, mass-produced small satellites in large constellations or clusters could be useful in many science missions such as gravity mapping, tracking of forest fires, finding water resources, etc. Constellation of satellites provide improved spatial and temporal resolution of the target. Small satellite constellations contribute innovative applications by replacing a single asset with several very capable spacecraft which opens the door to new applications. With increasing levels of autonomy, there will be a need for remote communication networks to enable communication between spacecraft. These space based networks will need to configure and maintain dynamic routes, manage intermediate nodes, and reconfigure themselves to achieve mission objectives. Hence, inter-satellite communication is a key aspect when satellites fly in formation. In this paper, we present the various researches being conducted in the small satellite community for implementing inter-satellite communications based on the Open System Interconnection (OSI) model. This paper also reviews the various design parameters applicable to the first three layers of the OSI model, i.e., physical, data link and network layer. Based on the survey, we also present a comprehensive list of design parameters useful for achieving inter-satellite communications for multiple small satellite missions. Specific topics include proposed solutions for some of the challenges faced by small satellite systems, enabling operations using a network of small satellites, and some examples of small satellite missions involving formation flying aspects.Comment: 51 pages, 21 Figures, 11 Tables, accepted in IEEE Communications Surveys and Tutorial

Earth Observing-1 Spacecraft Bus

The Earth Observing 1 (EO-1) spacecraft is one of the most trouble-free spacecraft that NASA has launched in the last ten years. A NASA New Millennium Program (NMP) mission dedicated to validating revolutionary technologies that will be used in future government and commercial missions, EO-1 was launched in November 2000 and flies in formation with Landsat 7. As the prime contractor, Swales Aerospace designed and built the spacecraft bus, integrated and tested the EO-1 observatory, and performed launch-site operations. Developed under the faster-better-cheaper philosophy, EO-1 is an example of a successful low-cost mission. We describe the mission, its new technologies, the results of on-orbit evaluation and the keys to EO-1 success, from early design to final testing

Real-time relative positioning of spacecraft over long baselines

This paper deals with the problem of real-time onboard relative positioning of low Earth orbit spacecraft over long baselines using the Global Positioning System. Large inter-satellite separations, up to hundreds of kilometers, are of interest to multistatic and bistatic Synthetic Aperture Radar applications, in which highly accurate relative positioning may be required in spite of the long baseline. To compute the baseline with high accuracy the integer nature of dual-frequency, double-difference carrier-phase ambiguities can be exploited. However, the large inter-satellite separation complicates the integer ambiguities determination task due to the presence of significant differential ionospheric delays and broadcast ephemeris errors. To overcome this problem, an original approach is proposed, combining an extended Kalman filter with an integer least square estimator in a closed-loop scheme, capable of fast on-the-fly integer ambiguities resolution. These integer solutions are then used to compute the relative positions with a single-epoch kinematic least square algorithm that processes ionospheric-free combinations of de-biased carrier-phase measurements. Approach performance and robustness are assessed by using the flight data of the Gravity Recovery and Climate Experiment mission. Results show that the baseline can be computed in real-time with decimeter-level accuracy in different operating conditions

Architectures and synchronization techniques for distributed satellite systems: a survey

Cohesive Distributed Satellite Systems (CDSSs) is a key enabling technology for the future of remote sensing and communication missions. However, they have to meet strict synchronization requirements before their use is generalized. When clock or local oscillator signals are generated locally at each of the distributed nodes, achieving exact synchronization in absolute phase, frequency, and time is a complex problem. In addition, satellite systems have significant resource constraints, especially for small satellites, which are envisioned to be part of the future CDSSs. Thus, the development of precise, robust, and resource-efficient synchronization techniques is essential for the advancement of future CDSSs. In this context, this survey aims to summarize and categorize the most relevant results on synchronization techniques for Distributed Satellite Systems (DSSs). First, some important architecture and system concepts are defined. Then, the synchronization methods reported in the literature are reviewed and categorized. This article also provides an extensive list of applications and examples of synchronization techniques for DSSs in addition to the most significant advances in other operations closely related to synchronization, such as inter-satellite ranging and relative position. The survey also provides a discussion on emerging data-driven synchronization techniques based on Machine Learning (ML). Finally, a compilation of current research activities and potential research topics is proposed, identifying problems and open challenges that can be useful for researchers in the field.This work was supported by the Luxembourg National Research Fund (FNR), through the CORE Project COHEsive SATellite (COHESAT): Cognitive Cohesive Networks of Distributed Units for Active and Passive Space Applications, under Grant FNR11689919.Award-winningPostprint (published version

Infrastructure Wi-Fi for connected autonomous vehicle positioning : a review of the state-of-the-art

In order to realize intelligent vehicular transport networks and self driving cars, connected autonomous vehicles (CAVs) are required to be able to estimate their position to the nearest centimeter. Traditional positioning in CAVs is realized by using a global navigation satellite system (GNSS) such as global positioning system (GPS) or by fusing weighted location parameters from a GNSS with an inertial navigation systems (INSs). In urban environments where Wi-Fi coverage is ubiquitous and GNSS signals experience signal blockage, multipath or non line-of-sight (NLOS) propagation, enterprise or carrier-grade Wi-Fi networks can be opportunistically used for localization or “fused” with GNSS to improve the localization accuracy and precision. While GNSS-free localization systems are in the literature, a survey of vehicle localization from the perspective of a Wi-Fi anchor/infrastructure is limited. Consequently, this review seeks to investigate recent technological advances relating to positioning techniques between an ego vehicle and a vehicular network infrastructure. Also discussed in this paper is an analysis of the location accuracy, complexity and applicability of surveyed literature with respect to intelligent transportation system requirements for CAVs. It is envisaged that hybrid vehicular localization systems will enable pervasive localization services for CAVs as they travel through urban canyons, dense foliage or multi-story car parks

TDRSS Augmentation System for Satellites

In 2015, NASA Goddard Space Flight Center (GSFC) reinvigorated the development of the TDRSS Augmentation Service for Satellites (TASS). TASS is a global, space-based, communications and navigation service for users of Global Navigation Satellite Systems(GNSS) and the Tracking and Data Relay Satellite System (TDRSS). TASS leverages the existing TDRSS to provide an S-band beacon radio navigation and messaging source to users at orbital altitudes 1400 km and below