MSIS Density Models

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The MSIS-00, MSIS-90, and MSIS-86 atmospheric models use a combination of F10.7 flux and Ap data to determine atmospheric density as a function of geopotential height. For more information on the MSIS models courtesy of the Naval Research Laboratory, see this website: NRL Mass Spectrometer, Incoherent Scatter Radar Extended Model.


By default, FreeFlyer will use the CSSI Space Weather file included in the installation with the MSIS models, but you can specify a different file or a custom drag model using a User-Created Atmospheric Drag File. This is useful for performing analysis using different predicted magnitudes and phases of the solar cycle.


This page is divided into the following sections:

Enabling MSIS Drag Modeling

Setting the Solar Flux Predictor File



Enabling MSIS Drag Modeling

The default atmospheric density model used for modeling the Earth's atmosphere is the Analytic Density Model. To enable an MSIS Density Model for a Spacecraft, edit the Spacecraft, proceed to the Force Model page, and select Earth from the list of celestial bodies as shown in the image below.


Then ensure that "MSIS-2000", "MSIS-90", or "MSIS-86" is selected in the Density Model drop-down menu.



To enable MSIS atmospheric density modeling via FreeFlyer script, use the following syntax:


Alias fm = (Spacecraft1.Propagator AsType RK89).ForceModel; // This alias is used to shorten the script examples below


fm.AtmosphericDensityModel = 4;


Where the AtmosphericDensityModel can be one of the following:

1 for Analytic density

2 for Harris-Priester density model

3 for Jacchia-Roberts density model

4 for MSIS-2000

5 for MSIS-90

6 for MSIS-86



Setting the Solar Flux Predictor File

By default, FreeFlyer uses the "solar_flux_cssi_space_weather.txt" data file for MSIS atmospheric modeling, but you can specify a different file using the "Solar Flux Predictor File" file browser shown in the image above or via FreeFlyer script using this syntax:


fm.SolarFluxFilename = "MSISdragfile.dat";


Where "MSISdragfile.dat" specifies the path and filename of the predictor file.



See Also

ForceModel Properties and Methods

Solar System settings that affect Spacecraft Propagation

CSSI Space Weather File

User-Created Atmospheric Drag Files