Frames#

In order to describe an orbit or a trajectory in space, we first need to define a suitable reference system. Normally, right-handed cartesian frames are used for this purpose. A cartesian frame is defined by specifying its origin and three orthogonal directions.

  • Origin: this point serves as the reference point for all measurements within the frame. The coordinates of this point will be (0, 0, 0) in the frame.

  • Axes: determine the orientation and directions of the coordinate axes. As they are mutually orthogonal, two directions are enough to define the triplet.

In mubody, coordinate frames are represented by Frame:

Frame(origin)

This is the basic frame class from which all other frame classes are derived.

ICRF([origin])

Main inertial frame used in mubody.

GCRF()

Main Earth-centered, equatorial inertial frame.

MIRF()

Main Moon-centered inertial frame.

RotatingFrame(origin, p1, p2)

Rotating frame based on the motion of one body (primary) with respect to another (secondary).

SynodicFrame(origin, p1, p2)

Rotating frame based on the motion of the CRTBP primaries.