Satellite Tool Kit

STK

STK 8.0 being used to plan a lunar lagrange orbit.
Developer(s)	Analytical Graphics, Inc.
Stable release	9.2.2 / January 2011
Operating system	Windows, Unix
Type	Technical computing
License	Proprietary
Website	STK product page

Satellite Tool Kit, often referred to by its initials STK, is a physics-based software package from Analytical Graphics, Inc. that allows engineers and scientists to perform complex analysis of land, sea, air, and space assets, and share results in one integrated solution. At the core of STK is a geometry engine that is designed to determine the time-dynamic position and attitude of assets, determining dynamic spatial relationships among all of the objects under consideration including the quality of those relationships or accesses given a number of complex, simultaneous constraining conditions. STK has been developed over 20 years as a commercial off the shelf software tool. Originally created to solve problems involving Earth-orbiting satellites, it is now used in both the aerospace and defense communities.

STK has more than 40,000 installations at over 800 global organizations such as NASA, ESA, CNES, DLR, Boeing, JAXA, ISRO, Lockheed Martin, Northrop Grumman, EADS, DOD, and Civil Air Patrol.^{[citation needed]}

The product is currently used in such areas as:

• C4ISR (Battlespace Management)
• Communications Analysis
• Electronic Warfare
• Geospatial Intelligence
• Missile Defense
• Spacecraft Mission Design
• Spacecraft Operations
• Space Exploration
• Unmanned Systems (UAVs)

History

In 1989, the three founders of Analytical Graphics, Inc - Paul Graziani, Scott Reynolds and Jim Poland, left GE Aerospace to create Satellite Tool Kit (STK) as an alternative to bespoke, project-specific aerospace software.

The original version of STK ran only on Sun Microsystems computers, but as PCs became more powerful, the code was converted to run on Windows.

STK was first adopted by the aerospace community for orbit analysis and access calculations (when a satellite can see a ground-station or image target), but as software was expanded, more modules were added that included the ability to perform calculations for communications systems, radar, interplanetary missions and orbit collision avoidance.

The addition of 3D viewing capabilities lead to the adoption of the tool by military users for real-time visualization of air, land and sea forces as well as the space component. STK has also been used by various news organizations to graphically depict complex events to a wider audience.

Interface

The interface to STK is a standard GUI display with customizable toolbars and dockable maps and 3D viewports. All analysis can be done through mouse and keyboard interaction.

In addition, there is a scripting interface named Connect that enables STK to act within a client/server environment (via TCP/IP) and is language independent. Users on Windows have the option of using STK programatically via OLE Automation.

Each analysis or design space within STK is called a scenario. Within each scenario any number of satellites, aircraft, targets, ships, communications systems or other objects can be created. Each scenario defines the default temporal limits to the child objects, as well as the base unit selection and properties. All of these properties can be overridden for each child object individually, as necessary. Only one scenario may exist at any one time, although data can be exported and reused in subsequent analyses.

For each object within a scenario, various reports and graphics (both static and dynamic) may be created. Relative parameters, between one object and another can also be reported and the effect of real-world restrictions (constraints) enabled so that more accurate reporting is obtained. Through the use of the constellation and chains objects, multiple child objects may be grouped together and the multipath interactions between them investigated.

Modules

STK is a modular product, in much the same way as MATLAB allows users to add modules to the baseline package to enhance specific functions.

Since the release of STK 8.0, the STK product range has been reorganized into Editions with additional add-on modules. A brief summary of the editions and modules is listed below.

STK Basic Edition

STK Basic is free to all users and is also the core module for all other STK modules. It allows access calculations to be performed between satellites and fixed points on the Earth's surface (or between satellites). There is also the ability to import satellites from the NORAD public satellite database (which can be updated online from within STK).

As of STK 8.0, users of the free version can also publish their scenarios to the VDF format. This means that scenarios can then be opened using the free AGI Viewer product.

STK Professional Edition

This adds to the Basic Edition with the following abilities:

• High fidelity trajectories
• Aircraft performance models
• Multi-point and group inter-visibility
• Constrained inter-visibility
• Complex sensor modeling
• Integrated 3D analysis tools
• Custom reports and graphs

STK Expert Edition

This adds a host of additional modules to what is provided in the STK Professional Edition

• STK/Integration Module (ability to integrate STK with external tools through Connect and/or through Matlab as well as embed STK into a custom application)
• STK/Terrain, Imagery & Maps Module (high-resolution imagery and terrain of the whole world)
• STK/Analyzer (perform trade-off studies and what-if analyses)
• STK/Attitude (integrate custom attitude control laws into STK)
• STK/Communications (high-fidelity link budget analysis)
• STK/Coverage (multi-point access calculations and navigation system analysis)
• STK/Radar (ground, space and airborne radar systems simulation)

Each of the above modules can be purchased individually and added to either the STK/Basic Edition or the STK/Professional Edition.

STK Specialized Analysis Modules

These are modules that can be added to the Basic, Professional or Expert editions:

• STK/Astrogator (interplanetary orbits, orbit maintenance, LEOP simulation)
• STK/Conjunction Analysis Tools (In-orbit collision prediction)
• STK/Missile Modeling Tools (missile simulation)
• STK/PODS (Precision Orbit Determination System - to reconstruct satellite orbits through observational data)
• STK/Scheduler (use scarce resources in the most efficient way)
• STK/Space Environment (radiation dose, debris flux, thermal loading)

Integration

STK can be embedded within another application (as an ActiveX component) or controlled from an external application (through TCP/IP or Component Object Model (COM)). Both integration techniques can make use of the connect scripting language to accomplish this task. There is also an object model for more "programmer oriented" integration methodologies. STK can be driven from a script that is run from the STK internal web browser in the free version of the tool. To control STK from an external source, or embed STK in another application requires the STK/Integration module.

Connect

Since connect is a messaging format, it has the advantage of being completely language independent. This allows applications and client tools to be created in the programming language of the user's or developer's choice. In practice, as long as it is possible to create a socket connection, send information through that socket and then receive information that way then STK can be controlled with connect using that language.

Applications have been developed in C, C++, C#, Perl, Visual Basic, VBScript, Java, JavaScript and MATLAB. Examples can also be found in the STK help files or downloaded from the AGI website.

External links

• The STK product page on the Analytical Graphics, Inc. website
• STK support resources
• STK maintenance release downloads
• Link to register the STK Basic Edition and get permanent license
• AGI Viewer download
• A list of STK tutorials for download