CASSINI Spacecraft Attitude tool

The VSE, GSE, JSE, and SSE coordinate systems are all defined as:

    Planetary Solar Ecliptic, Planet centered X=Sun, V2=Orbital normal.
    X      - Along the Planet->Sun line (S), positive towards the Sun.
    Y      - V2 x X
    Z      - Parallel to the Planetary orbital plane upward normal.

The Solar Ecliptic Spacecraft Axes Matrix is similar to these Planetary
Solar Ecliptic systems, with the X-Y plane in the Ecliptic.
The X-axis is defined by the intersection of the Ecliptic Plane
and the Earth's Dynamic Equator at the Jan. 1, 2000, epoch. That is, it is
the X-axis of the J2000 coordinate system. The Z-axis is the Ecliptic normal.

The SSQ coordinate system is Saturn Solar Equatorial, defined as follows:

    Saturn Solar Equatorial, Saturn centered Z=Omega, V2=Saturn-Sun vector.
    X      - In the Saturn->Sun plane, positive towards the Sun.
    Y      - Z x X
    Z      - Northward spin axis of Saturn.