N Plate Model

You can specify three types of plate orientations for the N Plate Model:

• Sun-pointing plates always orient the surface normal of the plate along the direction to the Sun.
• Axis-constrained Sun-pointing plates orient the surface normal as close to the direction of the Sun as possible. They are subject to rotation about a specified axis fixed in the body frame.
• Body-fixed plates have a fixed surface normal in the body frame of the spacecraft.

Each plate has its own properties, including area, surface normal in the body frame, and reflectivity and drag characteristics.

When used for modeling solar pressure, all plates are considered one-sided. Thus, if the Sun does not illuminate a plate as defined by the surface normal, the plate does not contribute to the solar pressure.

When used for modeling atmospheric drag, body plates are considered one-sided while Sun-pointing and Axis-constrained Sun-pointing plates are considered two-sided. If the surface normal of a body plate is 90 degrees or greater from the velocity direction, the plate does not contribute to drag forces. If the surface normal of a Sun-pointing plate or an Axis-constrained Sun-pointing plate is more than 90 degrees from the velocity direction, the unit vector in the opposite direction of the specified normal is used to compute the contribution to drag forces.