Release Notes

• GMAT is now used as the primary system for maneuver planning and product generation for the Solar Dynamics Observatory (SDO).

• GMAT is now used as the primary operational tool for orbit determination for the Solar and Heliospheric Observatory (SOHO) mission.

• GMAT is now used as the primary operational tool for maneuver planning, orbit determination, and product generation for the Advanced Composition Explorer (ACE) mission.

• GMAT is now used as the primary operational tool for maneuver planning, orbit determination, and product generation for the Wind mission.

• In April 2018, the Transiting Exoplanet Survey Satellite (TESS) mission is planned to launch. TESS has used GMAT as its primary tool for mission design and maneuver planning from proposal development through operations.

• In April 2018, the LRO project will hold an operational readiness review to perform final evaluation of GMAT to replace GTDS as the primary operational orbit determination (OD) tool for the Lunar Reconnaissance Orbiter (LRO).

The following new features and capabilities have been added to GMAT's estimation system.

As shown by the new features above, GMAT’s orbit determination (OD) capability has been significantly enhanced. As with all new releases, missions that use GMAT’s OD capability should perform a baseline set of regression/performance tests prior to using the new version of GMAT OD for operational purposes.

Example scripts:

GMAT now contains a built-in optimizer called Yukon, developed by the GMAT team. The algorithm uses an SQP line search algorithm with an active set QP-subproblem algorithm. Yukon is designed for small scale problems and is not applicable to large, sparse optimization problems. See the Yukon reference for more information.

• Tide modeling is improved, and GMAT now supports lunar tides.

• STM propagation now includes variational terms from drag models.

• The degree and order of STM contributions from harmonic gravity is now settable by the user and defaults to the maximum order on the gravity file or 100, whichever is lower.

• The buffer size that determines the number of plot points stored by the OrbitView Resource is now exposed to the user.

• Significant performance improvements have been made in the IRI2007 ionosphere model.

• The script editor highlights errors and warnings found on the first pass of parsing.

• GMAT now supports body fixed and TOD coordinate systems for Code 500 Ephemerides and supports all central bodies in the Code 500 Ephemeris format.

• The CommandEcho command has been added to GMAT to support printing commands to the message window and log file as they are executed in a mission sequence. This command is particularly useful when debugging user scripts. See the CommandEcho reference for more information.

• The Code500 propagator type now automatically detects the endianness when reading Code500 files.

• The STK ephemeris propagator now uses Hermite interpolation, and includes velocity information in the position interpolation for segments that contain fewer than 7 rows of data. Velocity interpolation for segments with fewer than 7 rows of data is performed by forming the hermite interpolating polynomial for position, and then differentiating the position interpolating polynomial to obtain the velocity.

• You can now set the step size of an ephemeris propagator during mission execution (i.e. after the BeginMissionSequence command).

• The startup file now allows optional updating of the user configuration file. This avoids issues encountered when simultaneous instances of GMAT try to write to the user config file at the same time, resulting in a system error.

• The Python data file utility now updates data files used by the IRI2007 model.

• The GMAT CMake based build system now supports plugin components developed by external groups.

• GMAT now supports GUI plugin components.

• Batch estimation now requires the use of fixed step integration.

• The RotationDataSource on CelestialBody Resources is deprecated and no longer has an effect.

• The Spacecraft EstimationStateType parameter is deprecated.

• The EphemerisFile OutputFormat options ‘UNIX’ and ‘PC’ are deprecated. ‘BigEndian’ and ‘LittleEndian’ should be used instead.

• The EarthTideModel on the ForceModel Resource has been renamed to TideModel

• GMAT now returns error codes via the command line interface to indicate if issues were encountered during system execution.

• When using the Write command to write Resource properties to a ReportFile, only scalar, real quantities are written. Properties that are either not real or are arrays are ignored and a warning is issued.

Over 112 bugs were closed in this release. See the "Critical Issues Fixed in R2018a" report for a list of critical bugs and resolutions in R2018a. See the "Minor Issues Fixed for R2018a" report for minor issues addressed in R2018a.

See the "All Known Issues for R2018a" report for a list of all known issues in R2018a.

There are several known issues in this release that we consider to be significant:

The following new features and capabilities have been added to GMAT.

GMAT now supports a propagator that uses AGI's .e ephemeris file format. See the Propagator reference for more information.

You can now manage empirical data updates using a Python file manager. The utility allows you to easily update leap second, EOP, space weather, and other files and optionally archive old versions. See the Configuring GMAT Data Files section for more information. When you run the the utility, you will see output like that shown below (the data below is only a partial summary of the output).

--------UPDATING GMAT LEAP SECOND FILE ------------------------------
Process Began At 2017-06-01-11:23:55
--------Downloading tai-utc.dat
tai-utc.dat downloaded successfully 
tai-utc.dat archived successfully to 2017-06-01-11h23m55s_tai-utc.dat
tai-utc.dat updated successfully
Process Finished At 2017-06-01-11:23:55

--------UPDATING GMAT EOP FILE --------------------------------
Process Began At 2017-06-01-11:23:55
--------Downloading eopc04_08.62-now
eopc04_08.62-now downloaded successfully 
eopc04_08.62-now archived successfully to 
                          2017-06-01-11h23m57s_eopc04_08.62-now
eopc04_08.62-now updated successfully

---------UPDATING SPICE LEAP SECOND FILE -----------------------
Process Began At 2017-06-01-11:23:57
--------Downloading naif0011.tls
SPICELeapSecondKernel.tls downloaded successfully
--------Downloading naif0012.tls
SPICELeapSecondKernel.tls downloaded successfully
SPICELeapSecondKernel.tls archived successfully to 
                      2017-06-01-11h24m00s_SPICELeapSecondKernel.tls
SPICELeapSecondKernel.tls updated successfully
Process Finished At 2017-06-01-11:24:00

GMAT now has a stand alone C++ library for solving optimal control problems via collocation (CSALT). The library is well tested and available for applications, and is currently undergoing integration into GMAT. The CSALT library is not exposed via GMAT interfaces, but users who are familiar with C++ programming can solve optimal control problems with CSALT now. The source code will be made available via SourceForge. CSALT integration into GMAT is underway and planned for completion in the next GMAT release. For more information on the CSALT Library see the paper entitled CSALT_CollocationBenchmarkingResults.pdf in the docs folder of the GMAT distribution.

A preliminary API is under development. The API is not available in the production release and is distributed separately on SourceForge in packages with the name "Alpha" in the title. The API employs SWIG to expose GMAT to several languages. Preliminary testing has been performed on the JAVA interface called from MATLAB. The code snippet below illustrates how to call through the JAVA interface from MATLAB to compute orbital accelerations on a spacecraft. Some testing of the Python binding as also been performed.

% Load GMAT
scriptFileName = fullfile(pwd, 'gmat.script');
[myMod, gmatBinPath, result] = load_gmat(scriptFileName);

% Get the SolarSystem object from GMAT
ss = myMod.GetDefaultSolarSystem();

% Prepare the force model to be used for dynamics
fm = myMod.GetODEModel('DefaultProp_ForceModel');
state = gmat.GmatState(6+6^2);
fm.SetSolarSystem(ss); % Set solar system pointer in force model
fm.SetState(state); % Provide force model with the state placeholder

% Create new Spacecraft
sat = gmat.Spacecraft('Sat'); 

% Create PropagationStateManager to manage calculation of derivatives
propManager = gmat.PropagationStateManager();
propManager.SetObject(sat); % Add sat PropagationStateManager
propManager.SetProperty('AMatrix', sat); % Want to calculate Jacobian
propManager.BuildState(); 

% Tell force model to use propmanager
fm.SetPropStateManager(propManager);
fm.UpdateInitialData(); % Update model with changes
fm.BuildModelFromMap(); % Sets up the models in the force model
state = gmat.gmat.convertJavaDoubleArray(x(:,tIndex));

% Compute the orbital accelerations including variational terms
fm.GetDerivatives(state, t(tIndex), 1); % Calculate derivatives
deriv = fm.GetDerivativeArray(); % Get calculated derivatives
derivArray = gmat.gmat.convertDoubleArray(deriv, 42);

• You can now define the name and location of the gmat startup and log file via the command line interface. This is useful when running multiple GMAT sessions simultaneously or when you have complex, custom file configurations.

• You can now write STK ephem files with units in meters (previously, only km was supported).

• You can now write STK ephem files without discrete event boundaries.

• GMAT now requires Python version 3.6.x.

• Schatten files no longer require the "PREDICTED SOLAR DATA" keyword at the top of the file.

• The names and locations of several data files used by GMAT are no longer hard coded and their names and locations are set in the file gmat_startup_file.txt located in the bin directory. If you use custom startup files, you MUST add the lines below to your startup file before GMAT will start. Note that the startup files distributed with GMAT have these lines added. This backwards compatiblity issue only affects users who customize their startup file.

  EARTH_LATEST_PCK_FILE    = PLANETARY_COEFF_PATH/earth_latest_high_prec.bpc
  EARTH_PCK_PREDICTED_FILE = PLANETARY_COEFF_PATH/SPICEEarthPredictedKernel.bpc
  EARTH_PCK_CURRENT_FILE   = PLANETARY_COEFF_PATH/SPICEEarthCurrentKernel.bpc
  LUNA_PCK_CURRENT_FILE    = PLANETARY_COEFF_PATH/SPICELunaCurrentKernel.bpc
  LUNA_FRAME_KERNEL_FILE   = PLANETARY_COEFF_PATH/SPICELunaFrameKernel.tf
  

• The syntax for navigation functionality has been significantly changed for consistency throughout the system. See the Deprecated Measurement Type Names section of the Tracking Data Types for OD Help for more details.

All known issues that affect this version of GMAT can be seen in the "Known Issues in R2017a" report in JIRA.

There are several known issues in this release that we consider to be significant:

GMAT now supports orbit determination with a focus on batch estimation of DSN data types including range and Doppler. We’ve been working on navigation functionality for several releases, but this is the first production release containing navigation functionality. Orbit determination functionality has undergone a rigorous QA process including shadow testing in GSFC’s Flight Dynamics Facility and is extensively documented in tutorials and reference material. Navigation components include BatchEstimator, Simulator, ErrorModel, StatisticsAcceptFilter, StatisticsRejectFilter, TrackingDataSet, and the RunEstimator and RunSimulator Commands. We recommend taking the tutorials first then reviewing the reference material for orbit determination components to get started.

See the Simulation and Estimation tutorials for more information.

GMAT now supports a propagator that uses GSFC’s Code 500 ephemeris file format. The Code 500 file format is legacy format still used by some systems at GSFC. This functionality allows users of GSFC legacy systems to simulate and analyze trajectories computed in systems such as GTDS.

See the Propagator reference for more information.

You can now export GMAT resources to files during the mission sequence execution. This is a powerful feature that allows you to save configurations at any point in a session for use by in later sessions or by other users.

See the Write Command reference for more information.

You can now load GMAT resources and script snippets from external files during the script initialization and mission execution. This is a powerful feature that allows you to reuse configurations across multiple users and/or scripts. This feature can also greatly simplify automation for operations and Monte-Carlo and parametric scanning that have use cases with a lot of common data but some data that changes from one execution to the next.

See the #Include reference for more information.

Using the built-in GetEphemStates function, you can now query SPICE, Code-500 and STK .e ephemeris types and for a spacecraft’s initial epoch, initial state, final epoch and final state in any GMAT supported epoch formats and coordinate systems. This allows you to perform numerical propagation using states off of ephemiris files for comparison and other analysis.

See the GetEphemStates referece for more information.

• You can now define the EOP file location in a script.

• The system now supports finite burn parameters that report the thrust component data for a finite burn. The parameters include total thrust from all thrusters in the three coordinate directions, the total acceleration from all thrusters in the three coordinate directions, and the total mass flow rate. Furthermore, you can now also report individual thruster parameters such as thrust magnitude, Isp and mass flow rate.

• GMAT now contains built-in string manipulations functions sprintf, strcmp, strcat, strfind, strrep.

• Several new built in math functions are implemented including a built-in cross product function. For manipulation of numeric data we've implemented mod, ceil, floor, fix. For random number generation we've implemented rand, randn, and SetSeed.

• You can now model finite burns that employ multiple tanks. Previous versions were limited to a single tank.

• GMAT now supports generation of STK's “.e” ephemeris format in addition those supported previously such as CCSDS-OEM, SPK and Code-500 formats.

• We've written over 130 pages of new, high-quality user documentation!

• The behavior of the GUI when using large fonts has been improved.

• You can now override the default NAIFId on a CelestialBody to allow using body centers or barycenters as the reference for built-in celestial bodies. Previously this field was read-only.

We updated the CMake-based build system that is used on all platforms. The CMake configuration is maintained by the GMAT team and distributed with the source code. Thanks to CMake, it is much easier to compile GMAT. See the wiki documentation for details. Note that old build files are no longer supported and are considered obsolete.

Don't forget you can purchase clothing and other items with the GMAT logo via ©Land's End, Inc at the GSFC Store . Once, you've chosen an item, make sure to select the GMAT logo!

All known issues that affect this version of GMAT can be seen in the "Known Issues in R2016a" report in JIRA.

There are several known issues in this release that we consider to be significant:

You can now write functions (sub-routines) in the GMAT script language. This powerful feature greatly expands the practical capability of the system and makes maintaining complex configurations simpler. This feature also enables sharing GMAT script utilities among among projects. If you need a new math computation, want to isolate a complex section of code, or re-use code, GMAT functions are a great solution.

See the Using GMAT Functions tutorial for more information.

GMAT now supports eclipse location. Under the hood GMAT calls NAIF SPICE routines. Thanks to the NAIF for making this great functionality available.

See the Eclipse Locator reference for more information.

GMAT now supports station contact location. Under the hood GMAT calls NAIF SPICE routines. Thanks to the NAIF for making this great functionality available.

See the Contact Locator reference for more information.

GMAT now supports an interface with Python. The power of the Python ecosystem can now be used with GMAT.

See the Python reference for more information.

GMAT now supports modelling of electric propulsion systems. Below is an examle showing GMAT modelling a cube-sat with electric propulsion in a lunar weak-stablity orbit. You can model electric tanks, thrusters, and power systems (both Solar and nuclear).

See the Electric Propulsion tutorial for more information.

GMAT now interfaces to Stanford Business Software, Inc. SNOPT Optimizer

See the SNOPT reference for more information.

You can now provide flux files for drag modelling including Schatten historical files and Center for Space Standards and Innovation (CSSI) Space Weather Files. This greatly improves long term orbital predictions and reconstructions in the Earth's atmosphere.

See the Propagator reference for more information.

You can now use a 3D model for celestial bodies in 3-D graphics.

See the Celestial Body reference for more information.

GMAT now displays a window showing solver variables and constraint values during execution. This helps track the progress of targeters and optimizers and is an important aid in troubleshooting convergence issues.

We've written over 70 pages of new, high-quality user documentation! We've also written two conference papers documenting our verification and validation process and results, and the flight qualification program and results for the Advanced Composition Explorer (ACE). Conference papers are located in the "docs" folder of the distribution.

We've posted training videos on YouTube . You can now take GMAT training even if you are unable to attend the live classes!

• The ChemicalTank Resource has been renamed to ChemicalTank to distinguish between chemical and electric systems.

• The ChemicalThruster Resource has been renamed to ChemicalThruster to distinguish between chemical and electric systems.

• The sensitivity of Spacecraft Resource settings such as ModelOffsetX, ModelRotationY, and ModelScale has changed in 3-D graphics.

• When applying an ImpulsiveBurn during backwards targeting, GMAT now attempts to compute maneuver values that are consistent with a forward targeting approach. The maneuver values reference the pre-manevuer velocity components instead of the post-maneuver components.

We've added extensive documentation describing how to add new Resources and Commands to GMAT. Resources and Commands are key to GMAT development and application. This documentation is essential reading for making fundamental extensions to GMAT. See the wiki documentation for details.

We developed a new CMake-based build system that is used on all platforms. The CMake configuration is maintained by the GMAT team and distributed with the source code. Thanks to CMake, it is much easier to compile GMAT. See the wiki documentation for details.

We updated SPICE to version N0065 and updated WxWidgets to version 3.0.2.

You can now purchase clothing and other items with the GMAT logo via ©Land's End, Inc at the GSFC Store . Once, you've chosen an item, make sure to select the GMAT logo!

All known issues that affect this version of GMAT can be seen in the "Known Issues in R2015a" report in JIRA.

There are several known issues in this release that we consider to be significant:

In GMAT R2014a, you can now specify colors for each segment of your trajectory independently, so you can clearly see where a segment begins and ends. This can help define portions of a trajectory, such as before or after maneuvers. All color handling has also been moved from the graphics resources (OrbitView and GroundTrackPlot) to the resources and commands controlling the trajectory (e.g. Spacecraft, Planet, Propagate).

On Spacecraft, the color specification has moved to the Visualization tab. See the circled area in the screenshot below. Colors for celestial bodies (Planet, Moon, Asteroid, etc.) are specified similarly.

The trajectory color associated with a particular trajectory segment can be changed by changing the color for that particular Propagate command. It will override the color for the Spacecraft being propagated for that segment only, and it will return to the default color afterwards.

Additionally, colors can now be specified either by name ('Blue') or by RGB value ([0 0 255]).

This release also adds participant labels in the graphics as well. As long as OrbitView.ShowLabels is enabled, each celestial body or Spacecraft in the plot will show its name next to it.

See the following example:

            Create Spacecraft aSat
aSat.OrbitColor = 'Blue'

Create Propagator aProp

Create OrbitView aView
aView.Add = {aSat, Earth}
aView.XYPlane = off
aView.Axes = off
aView.EnableConstellations = off
aView.ShowLabels = on

BeginMissionSequence
% plots in blue
Propagate aProp(aSat) {aSat.ElapsedSecs = 900}                     
aSat.OrbitColor = 'Green'
% plots in green
Propagate aProp(aSat) {aSat.ElapsedSecs = 900}             
 % plots in red        
Propagate aProp(aSat) {aSat.ElapsedSecs = 900, OrbitColor = Red}  
          

This example results in the following image:

See the Color reference, as well as the individual Spacecraft, CelestialBody, Propagate, and OrbitView references, for more information.

GMAT now supports six new common orbit state representations, developed with support by the Korea Aerospace Research Institute (KARI). The new representations are:

The new representations are available as options in the Spacecraft "State Type" list, and as options to the Spacecraft.DisplayStateType field.

See the Spacecraft Orbit State reference for more information.

GMAT now supports three new kinematic attitude models, developed with support by the Korea Aerospace Research Institute (KARI). The new representations are:

The new representations are available as options in the Spacecraft "Attitude" list, and as options to the Spacecraft.DisplayStateType field.

See the Spacecraft Attitude reference for more information.

GMAT now supports several new dynamics models and a new numerical integrator.

Below is a script example that illustrates the new algorithm and parameter options.

            Create Spacecraft aSat
Create Propagator aPropagator

Create ImpulsiveBurn aBurn
Create DifferentialCorrector aDC
%  This algorithm is often faster, as is ModifiedBroyden
aDC.Algorithm = Broyden  

Create OrbitView EarthView
EarthView.Add = {Earth,aSat}
EarthView.ViewScaleFactor = 5

Create ReportFile aReport 

BeginMissionSequence

%  Report targeter status here
Report aReport aDC.SolverStatus aDC.SolverState
Target aDC
    Vary aDC(aBurn.Element1 = 1.0, {Upper = 3, MaxStep = 0.4})
    Maneuver aBurn(aSat)
    Propagate aPropagator(aSat,{aSat.Apoapsis})
    Achieve aDC(aSat.RMAG = 42164)
EndTarget
%  Report targeter status here
Report aReport aDC.SolverStatus aDC.SolverState

          

You can now define settable parameters by using a dependency on the LHS of an assignment command:

            Create Spacecraft aSat

BeginMissionSequence

aSat.EarthFixed.X = 7000
aSat.EarthMJ2000Eq.VZ = 1
          

• Color settings for Resources displayed in graphics are now configured on the Resource and via the Propagate command. OrbitColor and TargetColor fields on graphics resources are no longer used.. See the Spacecraft Visualization reference, and Propagate command reference for details.

• AtmosDensity is now reported in units of kg/km^3. See the Calculation Parameter reference for details.

All known issues that affect this version of GMAT can be seen in the "Known Issues in R2014a" report in JIRA.

There are several known issues in this release that we consider to be significant:

GMAT now can load Spacecraft state and physical properties data directly from a data file. A new resource, FileInterface, controls the interface to the data file, and the new Set command lets you apply the data as a part of the Mission Sequence.

See the following example:

            Create Spacecraft aSat
Create FileInterface tvhf
tvhf.Filename = 'statevec.txt'
tvhf.Format = 'TVHF_ASCII'

BeginMissionSequence

Set aSat tvhf
          

See the FileInterface and Set references for more information.

GMAT's EphemerisFile resource can now write a Code-500 format ephemeris file. The Code-500 format is a binary ephemeris format defined by the NASA Goddard Space Flight Center Flight Dynamics Facility.

            Create Spacecraft sc
Create Propagator prop
Create EphemerisFile ephem
ephem.Spacecraft = sc
ephem.Filename = 'ephem.eph'
ephem.FileFormat = 'Code-500'
ephem.StepSize = 60
ephem.OutputFormat = 'PC'

BeginMissionSequence

Propagate prop(sc) {sc.ElapsedDays = 1}
          

See the EphemerisFile reference for more information on this format.

A local aligned-constrainted coordinate system is one defined by an alignment vector (defined based on the position of a reference object with respect to the origin) and two constraint vectors. This is a highly flexible coordinate system that can be defined in many ways, depending on mission needs. To use it, select the LocalAlignedConstraned axes type when creating a new CoordinateSystem.

            Create CoordinateSystem ACECoordSys
ACECoordSys.Origin = Earth
ACECoordSys.Axes = LocalAlignedConstrained
ACECoordSys.ReferenceObject = ACE
ACECoordSys.AlignmentVectorX = 0
ACECoordSys.AlignmentVectorY = 0
ACECoordSys.AlignmentVectorZ = 1
ACECoordSys.ConstraintVectorX = 1
ACECoordSys.ConstraintVectorY = 0
ACECoordSys.ConstraintVectorY = 0
ACECoordSys.ConstraintCoordinateSystem = EarthMJ2000Ec
ACECoordSys.ConstraintReferenceVectorX = 0
ACECoordSys.ConstraintReferenceVectorY = 0
ACECoordSys.ConstraintReferenceVectorZ = 1
          

See the CoordinateSystem reference for more information.

You can now access ForceModel-dependent parameters, such as Spacecraft acceleration and atmospheric density. The new parameters are: