Aviator Software Architecture
Tom Neely, AGI
The Aviator expert system comprises a large COM API with more than 200 objects implementing 500 interfaces along with 100 ActiveX controls. This talk will examine how this system is integrated with STK and how it can be integrated with other applications.
Attitude Modeling in STK
Dr. Sergei Tanygin, AGI
Attitude modeling is an important part of many computations performed in STK including sensor targeting and intervisibility analysis, force modeling, antenna link budget, sensor swath, coverage and visualization. The models range from simple inertially fixed alignment to numerically integrated attitude. The models can be customized using various configuration parameters and new models can be created using custom plugins and components from Vector Geometry Tool. Attitude information is available in various reports, graphs and 3D displays. It can also be exported into a file for further processing outside of STK. Conversely, external attitude data can be imported into STK via file or Connect interface. STK 9 includes several new types of attitude models available via the Vector Geometry Tool.
David A. Vallado, Center for Space Standards & Innovation
Covariance information from orbit determination is becoming a popular means to assess the validity of many space operations. There have been scattered claims and discussion of realistic covariance, but few, if any, detailed studies to demonstrate the actual performance against independent references. This paper shows the performance of predicted ephemeris errors against reference and precision orbits, to what the covariance propagation provides. Several satellite orbital classes are studied.
Intimate Communication Network Simulation with STK and QualNet
Dr. David Finkleman, CSSI
This presentation is an introduction to new collaboration between STK and communication network simulations. The new paradigm is to replace QualNet physical layer calls with the rich STK physical layer, as opposed to the previous approach where communication transactions controlled through applications were invoked only when all STK constraints were satisfied. Our experience with this important collaboration led to a more intimate exchange beyond STK Connect commands. The fundamental exchange objects are QualNet network interfaces. These interfaces acquire properties of transmitters and receivers in STK with the attributes that the communication objects inherit from sensors and platforms. Interfaces on host objects can be linked wirelessly or assigned to wireless subnets. The STK and QualNet object browsers are available in the same graphical user interface. The user can coordinate and execute both simulations simultaneously. Using practical airborne relay and satellite scenarios, we will show that physical access is necessary but not sufficient. We will demonstrate how higher layer network interactions and background traffic can inhibit links that enjoy complete physical access.
Maximizing STK 9's Automation and SOA Capabilities
Dr. T.S. Kelso, Center for Space Standards & Innovation
Many users operate in an environment where analysts must perform structured tasks with standard data. Oftentimes, these analysts need to use the power of STK but may have rudimentary skills in implementing their workflows in a standardized fashion that ensures effective use of their time. The good news is that STK 9 incorporates several new features that make it easy to deploy standardized workflows that use approved data sources. We will examine how standardized workflows can be deployed from a corporate Intranet or the Internet to provide STK-based tools for analysis. Examples from Rev 2 of SOCRATES-GEO will be used to illustrate how this supports conjunction monitoring.
Methods of Orbit Propagation
Dr. Vince Coppola, AGI
AGI products model orbit trajectories in many ways. In this presentation, a variety of methods including closed-form analytical solutions, general perturbations, semi-analytic solutions and special perturbations will be described. We will discuss advantages and disadvantages of the various methods, and their applications with AGI products.
Modeling Antenna Attitude and Positional Offsets
Dr. Haroon Rashid, AGI
This presentation focuses on the enhancements made to the STK/Communications module for more accurately modeling antenna attitude and positional offsets relative to the parent object. This becomes critical when computing access intervals and modeling link degradation due to obscuration of the parent body. This presentation will also touch on the new STK 9 antenna object and best practices for using it in modeling communications systems.
Modeling Dynamic Urban Propagation Loss
Dr. Haroon Rashid, AGI
Computing RF urban propagation loss is a challenging task due to high barriers imposed by the urban construction. The line of sight (LOS) obstructions due to buildings, reflections from the building faces, multipath echoes and propagation through walls present tricky situations. The problem can be further compounded by the dynamics of the objects. One or both terminals of a communications link may be mobile at the same time and may be moving in or out of the urban environment. We review several possible configurations in this session. We start with the communications terminals in space and move toward an urban area, covering situations where one terminal is in an urban environment, including the case where both terminals may be outside the urban area but the communications may be passing through or grazing the urban landscape. A couple of examples are presented and a possible future development direction is discussed.
Moving Heaven and Earth: Implementing the International Celestial Reference Frame
John Seago, AGI
The IAU 2000A precession-nutation theory relates the International Celestial Reference Frame (ICRF) to the International Terrestrial Reference Frame (ITRF). This new theory became the official IAU standard in 2003. Unfortunately, we now have several documented or implemented standards that relate the ICRF and ITRF but differ to within several micro-arcseconds. These differences are mainly caused by changes of variables and very slight changes in modeling, and are fairly close to the original level of precision of the IAU 2000A nutation model (one micro-arcsecond). For example, the IAU replaced the IAU 2000A precession component with a new precession model that officially went into effect January 2009. AGI has now implemented many of these methods, but added a bonus method: one that maintains the original level of precision but runs almost 400 times faster.
New Computational Tools for STK 9
Dr. Sergei Tanygin, AGI
Timeline and Calculation tools are developed to unify, standardize and customize use of time and other calculations within STK. The tools are designed using the same methodology as Vector Geometry Tool. This includes having various types of components for different calculations, placing these components within a common browser, accessing them by name via GUI, Connect and eventually Object Model, providing a number of pre-configured components, creating new custom components using existing components and using template components for all instances of the same STK object type.
Powered Missile Flight Simulation Using STK/Missile Modeling Tools
Chris Weekley, Science Applications International Corporation (SAIC)
For designers and analysts of ballistic missiles, kinetic interceptors, sensor systems and integrated missile defense architectures, STK/Missile Modeling Tools (STK/MMT) simulates threat trajectories, intercept engagements and defense system performance. STK/MMT delivers system-level fidelity without complexity. This allows users to incorporate realistic missile simulation into analysis without specialized training or knowledge. This presentation describes the background and modeling detail employed in STK/MMT to simulate boost, midcourse and terminal phases of ballistic missile trajectories. Topics include software heritage to the Strategic and Theater Attack Modeling Process (STAMP) application funded by the National Air & Space Intelligence Center (NASIC) and modeling approaches for gravity, atmospheric drag, propulsion, guidance, post-boost vehicle maneuvers, free flight and reentry.
SensorCAD Under the Hood: Radiometrics and the Electro-Optical Sensor Model
Bob Anderson, Space Dynamics Lab - Utah State University
This presentation will introduce the measurement of optical radiation as it relates to the SensorCAD Electro-Optical sensor model. Topics covered include:
- Optical radiation and its generation by sources being imaged and its transport to the sensor
- Transformation of the optical radiation into a digital readout
- Noise and Signal to Noise Ratio
Related terms and their meanings, e.g. dynamic range, quantum efficiency, relative spectral response
Space Environment and Effects Toolkit (SEET) Technical Primer
Dr. Richard A. Quinn and Paul P. Whelan, Atmospheric and Environmental Research, Inc. (AER)
AER's Space Environment and Effects Toolkit (SEET) provides extensive modeling of the near-Earth space environment, with the capability to predict various effects on space vehicles. SEET's functionality is provided by six components consisting of scientific models of the space environment, including: Radiation Environment, South Atlantic Anomaly (SAA) Transit, Particle Impacts, Near-Earth Heavy Ion Environment, Vehicle Temperature and Magnetic Fields. These components are seamlessly integrated into the overall STK user interface and fully accessible through STK Engine as well. This talk will focus on giving a technical underpinning for the SEET, SAA-Transit Component in the context of a typical use case. The SAA is a near-Earth region of highly energetic charged particles which can easily penetrate spacecraft and create negative impacts on internal electronics. Impacts include single-event upsets (SEUs) and internal deep-dielectric charging/discharging. The current SAA model was developed at the Air Force Research Laboratory by binning six years of data from the Compact Environment Anomaly Sensor on-board the TSX-5 satellite. A general description of the physics of the SAA will be given, as well as a technical review of the model itself, followed by a description of a typical use case, computing entrance and exit times for a LEO orbit and ways that end-users (e.g. satellite operators) could expand the utility of the model using their own anomaly databases.
Trajectory Optimization in STK 9
Patrick Williams, Penn State University
As of the release of STK 8.1, users were given the ability to insert their own targeting profiles in STK/Astrogator via a search plugin. These plugins can be used to implement user-defined optimization algorithms (either coded in-house or from an external source) within STK/Astrogator, allowing for optimization of mission parameters and mission segments. In the fall 2009 release of STK 9.1, users will also be able to add and integrate their own variables to STK's internal state vector. This process allows for trajectory optimization through an indirect optimal control method. Both a basic optimization search plugin and optimal control setup will be described, as well as how to use them in coordination to solve the cumbersome optimal control problem.
Using Root-Finding and Optimization Search Algorithms in Maneuver Planning
Paul Black, AGI
Root-finding and optimization search algorithms play an important role in trajectory design and maneuver planning problems. The algorithms find the times, directions and magnitudes of maneuvers needed to meet mission requirements. In this presentation, several such algorithms are discussed, including the bisection search, Newton-Raphson, differential correction and gradient optimization methods. Examples of using these methods with STK/Astrogator to solve maneuver planning problems are provided.
Wireless InSite Real-Time® Urban Propagation: Reasonable Fidelity in Real Time
Gregory Skidmore, Remcom
AGI's STK/Communications software is being enhanced to provide EM urban propagation calculations using Remcom's Wireless InSite Real-Time. This talk provides an overview of Wireless InSite Real-Time, which combines optimized ray-tracing techniques developed at Remcom and Wireless InSite's powerful geometry processing capabilities with novel techniques to quickly estimate field levels in an urban environment. The result is a capability to predict the path loss between a given transmitter and receiver pair with calculation time on the order of a millisecond. The discussion covers the suite of real-time models that are included in the calculation engine and describes the general algorithms used in each model. It concludes with a comparison of results between higher-fidelity physics models and the real-time models, along with the computational savings (orders of magnitude) that the real-time models provide over full physics models.