Release Notes for FreeFlyer 7.7

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New Features in FreeFlyer 7.7

Flat Plate SRP Modeling

Flat plate models can now be defined and used for high-fidelity solar radiation pressure modeling

oThese plates can be made to automatically track the Sun using either single-axis or two-axis rotation

oFlat plate models are able to be visualized in ViewWindow objects, providing visual insight into the plates' size, location, normal direction, and rotation axes

oThe solar radiation pressure force and torques generated by plate models can be queried

oFlat plates are one-sided and only generate solar radiation pressure force when sunlight hits the active face

These plates are transparent to solar radiation pressure from the other side, which generates zero force

Flat plate models can be exported and imported for ease of configuration


Propagation Enhancements

The SGP4 and SGP4-XP algorithm from the US Space Force Astro Standards v8.2.1 library can now be used for Spacecraft propagation and SGP4-to-Cartesian element set conversions

TLEs formatted using Alpha-5 encoding for Spacecraft identifiers can now be processed

Added support for the CSSI Space Weather File for ingesting the solar flux data required for atmospheric drag modeling with the Jacchia-Roberts and MSIS models


Orbit Determination Enhancements

Added support for the reading and writing of Rinex 3.0 formatted navigation and observation data

Galileo Global Navigation Satellite System (GNSS) data processing is supported within Rinex 3.0 analyses

Maneuvers can now be added to a sequential filter (e.g. Extended Kalman Filter) after it has begun processing


Licensing Enhancements

Network licensing features can now be individually registered with FF.exe using the -lsfs command line switch in conjunction with the -rls switch

Increased the amount of time that a license can be borrowed within FreeFlyer to be limited only by the maximum duration allowed by FlexNet licensing


Notable Fixes

Procedure performance has been improved, reducing overhead time associated with the Call command to match that of FreeFlyer script written without Procedures

Performance of the Diagnostics object has been improved considerably and large numbers of accumulated errors will no longer cause FreeFlyer to crash



Migrating to FreeFlyer 7.7

While we always strive to maintain 100% backwards compatibility in our new releases, our efforts to make FreeFlyer more flexible and consistent in FreeFlyer 7.7 and higher have necessitated a few changes which may require user intervention when migrating your existing Mission Plans. These changes are outlined below.


Modeling and Numerics

FreeFlyer's Norad propagator has been updated to use the Space Force's official implementation of the SGP4 algorithm, resulting in very minor numeric differences from different floating point math operations when used. Previously, the Norad propagator contained a different implementation of the same algorithm.


Euler angles are now normalized to a cyclic range of 0 to 360 degrees, which could affect Plot output when reporting these values between FreeFlyer 7.7 and older versions.


When applying a FiniteBurn to a Spacecraft, a new error will be thrown when all of the following conditions are met.

oThe FiniteBurn object is configured in Attitude mode with FiniteBurn.AttitudeSystem = 3

oThe Spacecraft object being maneuvered is using a custom CoordinateSystem object as its attitude reference frame via Spacecraft.SetAttitudeRefFrame()

oThe Spacecraft object itself is used in determining the attitude of the CoordinateSystem object used as its attitude reference frame

Prior to this change, FreeFlyer would not reevaluate the CoordinateSystem sufficiently during the internal propagation of an executed FiniteBurn, resulting in unexpected, reduced accuracy.


Orbit number calculations are now disabled by default during Spacecraft propagation to improve performance. Setting Spacecraft.OrbitNumberCalculationsEnabled to 1 will enable them on a per-Spacecraft basis.



Removing the Earth, Sun, or Moon from a ViewWindow is no longer allowed to prevent issues where these objects are otherwise expected. To turn them off in a particular view, the ViewWindow.SetShowObject() method should be used instead.


Several of the default data files packaged with the FreeFlyer installation now have new filenames. Solar flux data files, Harris Priester density tables, and ground station data files now follow a new file naming convention. Any Mission Plans that are hard-coded to look for specific file names will need to be updated.


Various Objects, Properties, Methods, and Functions have been deprecated

oDeprecated Objects, Properties, Methods, and Functions are elements of FreeFlyer which are no longer recommended for use. The description of each deprecated element indicates the new recommended way to achieve the functionality of that element. The complete list of affected elements is given on the Deprecated Objects, Properties, Methods, and Functions page.



See Also

Release History