Spacecraft Axes
The spacecraft axes are used to define the primary and secondary, and consequently the third, axes of the spacecraft coordinate system orientation. This is a cartesian coordinate system with its origin at the location of the spacecraft in orbit. Multiple Spacecraft Axes features can be defined. They are then available in the Generate Events Interface features.
Set the Primary axis to From primary selection, +X direction, +Y direction, or User defined to define the primary pointing direction. When From primary selection is selected, the primary pointing direction is defined as the normalized averaged normal vector over the selected surfaces. When User defined is selected, the primary point direction is defined as the user defined vector divided by its norm.
Similar user inputs are available to define the Secondary axis.
The tertiary axis is then defined as the normalized cross product of the primary and secondary axis.
If the primary and secondary axis are collinear an error is triggered. In case the secondary vector is not a unit vector perpendicular to the primary axis, the actual secondary axis is the normalized projection of the secondary vector onto the plane normal to the primary axis.
See Theory for Orbital Thermal Loads for the definition of the spacecraft position over time and the coordinate system transformation.
Location in User Interface
Context Menus
Orbital Thermal Loads>Spacecraft Axes
Ribbon
Physics tab with Orbital Thermal Loads selected:
Global>Spacecraft Axes