Guides

The following guides are designed to familiarize you with specific FreeFlyer topics. Each guide contains background information, script examples, and FreeFlyer screen shots as appropriate. You will also find links to other related sections of this help file, including the objects and commands that are relevant to each topic.

Table of Contents

See the top-level guide pages listed below for a full listing of all guides available in that section.

Overviews

Spacecraft Propagation

The Spacecraft Propagation guide deals with the core object in FreeFlyer, the Spacecraft, and how to use it to the fullest extent as is necessary for your mission. FreeFlyer is a tool for spacecraft mission design and analysis. Because spacecraft are dynamic objects, a mission design and analysis tool must simulate the motion of the spacecraft, both spatially and temporally. FreeFlyer uses a "Propagator" object to model spacecraft motion. There are two ways to propagate, or "step", the Spacecraft: an integration algorithm can be used in conjunction with a force model to step the Spacecraft through time, or an external ephemeris file can be used to specify spacecraft state information including epoch, location, attitude, and rates of change.

Generating Output

The Generating Output guide focuses on the myriad ways in which FreeFlyer can generate output, such as with reports, plots, data tables, and how the user can easily control the many knobs associated with those output formats. Many types of output can be generated in FreeFlyer. You can easily create visual, graphical, or numerical output in a variety of ways. FreeFlyer provides both object and command versions of each output type. Generally, the command will be quicker and easier to use, but the object provides greater flexibility and more customization options.

FreeFlyer Scripting

The FreeFlyer Scripting guide focuses on how to use the FreeFlyer scripting language within FreeForm script editor blocks in the Mission Sequence. Firstly, basic topics such as the different types of operators flow control are covered here so that the user can structure scripts appropriately. Beyond that are the specialized script organizational elements, such as Procedures and Macros, and how to utilize the debugger to diagnose issues encountered in one's script.

Coverage and Contact Analysis

The Coverage and Contact Analysis guide is designed to instruct the reader in how to determine visibility and an assortment of varied contact types among Spacecraft objects, GroundVehicle objects, Sensor objects, GroundStation objects, and more depending on the context. Sensor and GroundStation objects are the fundamental objects used in coverage and contact analysis. FreeFlyer uses these objects to model position, orientation, and field of view (FOV) information. Once you have set up your Sensor and GroundStation objects, you can easily generate reports, plots, or 3D views to display contact information. Additional objects useful for coverage and contact analysis include the PointGroup, the Region, the ProximityZone, and Terrain, all of which are discussed in this section.

Maneuvering and Targeting

The Maneuvering and Targeting guide discusses the two eponymous topics in great detail both individually and in relation to one another as they go hand-in-hand in space mission design and analysis. Maneuvering deals with acting on a spacecraft's orbit with changes in its velocity vector, while targeting oftentimes involves targeting a specific set of maneuvers that will get your spacecraft to a specific orbit that meets a given set of criteria. In FreeFlyer, both items are handled with a variety of objects and commands to facilitate easy design of Mission Plans using these subjects.

Interfacing with External Resources

The Interfacing with External Resources guide's focus is on FreeFlyer's inclusion of several mechanisms for interfacing with other tools and resources. The FileInterface object and other string parsing capabilities allow FreeFlyer to read in any arbitrarily formatted external file. The MatlabInterface is used to establish communications between MATLAB® and FreeFlyer. The DataBase object enables connectivity to database management systems (DBMS). The Socket object allows you to send and receive data to and from a remote program via TCP/IP. The Email object allows data local to FreeFlyer to be transmitted to an external user via email.

Orbit Determination

The Orbit Determination guide discusses FreeFlyer's orbit determination (OD) system, which is a robust, easy-to-use, and convenient system for applying essentially a weighted curve-fit between a user's measurements and the propagated truth state of a Spacecraft. Orbit determination takes many forms and has many options available for designing and tuning a system to minimize residuals and maximize likeliness of convergence.

Interplanetary Analysis

The Interplanetary Analysis guide showcases FreeFlyer's diverse functionality for the support of interplanetary mission design and analysis. You can use Vector and CoordinateSystem objects to define non-Earth-centered reference frames, define custom CelestialObject objects and specify them as the central body for a Spacecraft or include their effects in the Spacecraft force model, and modify various properties of FreeFlyer's solar system model.

Terrain Modeling

The Terrain guide focuses on how to use the Terrain object to the fullest extent as is necessary for your mission. Many types of analyses can incorporate terrain in their coverage and contact evaluations, including for communications and space situational awareness. The Terrain guide closely relates to GroundVehicle objects as a means for propagating directly on top of terrain or at a specific height above terrain.

Optimization

The Optimization guide illustrates FreeFlyer's optimization capability to design multivariable optimizers for your mission. Users can configure any number of state variables and constraints to define their problem, then create a custom objective function that the optimization engine can minimize or maximize.