Solar Radiation Pressure
|Top Previous Next|
Spacecraft orbits are influenced by solar radiation pressure (SRP) emitted from the Sun. The accelerations due to the force of the solar radiation pressure act in the direction away from the Sun, and therefore the effect is seen regardless of the Spacecraft's orientation, so long as the Spacecraft is not in shadow. The magnitude of the applied force is proportional to the mass, cross-sectional area normal to the direction to the Sun, the coefficient of reflectivity (CR) of the Spacecraft, and the inverse of the square of the distance from the Spacecraft to the Sun. These parameters provide flexibility in modeling the solar radiation pressure to match your mission's needs.
By default, SRP modeling is disabled in FreeFlyer, but can be easily enabled as described below.
The formula used to calculate the acceleration due to solar radiation pressure is:
(1) Larson, W. J. and Wertz, J. R. Space Mission Analysis and Design (2nd Ed.), Microcosm Press, El Segundo, CA
(2) Equation 3-59, Page 76 of Wertz, James R., Spacecraft Attitude Determination and Control, Kluwer Academic Publishers, Boston, MA
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:
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.
•ForceModel Properties and Methods
•Solar Radiation Pressure Modeled using Other Accelerations Sample Mission Plan