FACE – Facility for Attitude Control Experiments
One task of the Department of Guidance, Navigation and Control Systems is to develop and verify satellite attitude control systems. The FACE facility was designed to meet this objective. Its main task is to create an artificial environment, which simulates the environmental conditions in space (zero gravity, magnetic field, solar radiation, earth albedo, stellar background) as good as possible.
The most difficult condition to simulate is the force free rotation of the satellite body. This is difficult to achieve on the Earth’s surface since gravity always affects the satellite body. However, a trick is used to create realistic satellite motion on Earth: an air-bearing table.
The air-bearing table is a platform on which a perfect hemisphere (callote) is installed. On the opposing side of the embedded callote is a stator. A thin cushion of air separates the callote and the stator, making the callote act as an air bearing. In this manner the assembly platform can spin almost frictionless around all three axes. The effects of free three-axes rotation in space can be simulated by using this trick.
The FACE facility can also generate a realistic magnetic environment using a Helmholtz coil set-up. It consists of six circular magnet coils installed around the air-bearing table. With the help of these coils an artificial magnetic field is generated simulating the conditions in Earth orbit.
Additionally, the facility can generate artificial solar radiation. Light from a studio spotlight can be directed via a mirror on the platform.
The actual components of the attitude control system are mounted on the air-bearing table’s platform. Thus a nearly self-sustaining satellite is arranged on the platform which can be employed in various tests.