Solar Radiation Pressure

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Spacecraft orbits are influenced by solar radiation pressure (SRP) emitted from the Sun. There are two SRP modeling options in FreeFlyer, spherical and flat plate. Spherical is simpler and requires very little setup, while flat plate is higher fidelity and allows you to configure the geometry and reflectivity of individual plates that represent your Spacecraft’s geometry.


By default, SRP modeling is disabled in FreeFlyer, but can be easily enabled as described below.


Enabling SRP Modeling

To enable SRP forces, edit the Spacecraft object, proceed to the Force Model page, and check the "Solar Radiation Pressure" checkbox, as shown below.



To enable or disable Solar Radiation Pressure via FreeFlyer script, use the syntax shown below:


// To enable SRP

(Spacecraft1.Propagator AsType RK89).ForceModel.SRP = 1;


// To disable SRP

(Spacecraft1.Propagator AsType RK89).ForceModel.SRP = 0;


To specify which SRP calculation mode to use, the ForceModel.SRPForceGeometry property can be used as shown below:


(Spacecraft1.Propagator AsType Integrator).ForceModel.SRPForceGeometry = 1; // 0 = Spherical

                                                                            // 1 = Flat Plate


Spacecraft.Accelerations is an array containing the accelerations due to various forces on the Spacecraft and can be used to view the solar radiation pressure forces acting on a Spacecraft. The example below shows how to view force contributions from each source.


For i = 0 to Spacecraft1.Accelerations.Count-1;


      // Report the value of each acceleration component

      Report Spacecraft1.Accelerations[i].Description, Spacecraft1.Accelerations[i].Acceleration;




See Also

ForceModel Properties and Methods

ForceModel.SRP property

Spherical Model

Flat Plate Model

Solar System settings that affect Spacecraft Propagation

Solar Radiation Pressure Modeled using Other Accelerations Sample Mission Plan