The Spacelab Instrument Pointing Subsystem /IPS/ Its automated and non-automated functions

The Spacelab Instrument Pointing Subsystem (IPS) is a 3-axis gimbal system which allows rotational decoupling of a payload up to 2000 kg from motions of the Shuttle Orbiter, and will provide directional accuracy in the region of arc-seconds exceeding that of the Orbiter (which is plus or minus 0.1 deg). IPS functions may be carried out automatically when they are too complex or beyond the capability of the operator. Automated functions include stellar and solar identification, sensory data filtering, payload stabilization, large angle maneuvering and scanning, and may be controlled by uplink commands from thy ground or by the experiment itself. Nonautomated functions provide operational flexibility. Operation modes include inertially fixed fine pointing, solar (offset) pointing and earth pointing (i.e. tracking an earth-fixed target and pointing with respect to the local vertical).