Tabulated Area Vector Model

The Tabulated Area Vector model uses a (*.spad) file, an output from the Solar Pressure and Atmospheric Drag (SPAD) tool used by NASA Goddard Space Flight Center. SPAD is an ASCII-formatted file with header and data sections. Files contain:

• a table of area vectors that represent the direction, area, and reflectivity associated with light coming from an associated direction in the body frame
• metadata that describes the data table

STK interpolates the table of area vectors associated with incident light directions, all expressed in the body frame of the satellite. You can construct tables of area vectors in a manner that accounts for self-shadowing, which is not available with NPlate models. Area vectors combine the direction of the acceleration of the satellite due to solar pressure and a magnitude that captures the combined effects of area and reflectivity. For example, a spherical satellite made of uniform material would have area vectors of constant magnitude and a direction parallel to the direction to the sun. The magnitude of the area vectors in the case of a sphere would be equal the product (Cr * A) in the Spherical solar pressure model. A single stochastic parameter representing a scale factor for the resultant acceleration can be estimated.