Hughes Aircraft Company

Joseph H Hayden

A Dorian Challoner

Donald C Chang

Steven J Stadnick

Richard A Fowell

U A Von Der Embse

Gene E Allen

Ken Y Huang

Shibu Basuthakur

Mark P Mitchell

Louis Gomberg

A battery reconditioning system and method for a spacecraft which utilizes a single battery as a secondary source of power for spacecraft electrical loads (10). The battery (14) includes a plurality of serially connected packs (30-36) each including a plurality of cells (40-46) connected in series. Sensors (50-56) are provided with each pack for sensing the state of charge of the pack. Battery charging circuitry (12,18,20) is controlled from control circuitry (22,52) which is responsive to the state of charge sensors as well as commands from a ground station transceiver (57). Reconditioning resistors (60-66) are adapted to be connected across the individual packs through switches (70-76) which are controlled by the control circuitry to discharge the pack at a relatively high rate when reconditioning is desired. After a pack is discharged to a desired low state of charge, its reconditioning resistor is disconnected and all packs are recharged in series. A pair of diodes (80A,80B-86A,86B) are connected across each pack and provide a low resistance current path in the event a fault clearing current is required from the battery during reconditioning of a pack.

System and method for reconditioning spacecraft battery

A magnetic torquing system for a spacecraft using conducting coils is disclosed. In one embodiment, the conductors (44, 46) on a spacecraft's (10) solar wing (28, 30) which connect the solar cell strings (38) to the voltage controller (48) are wired to produce a magnetic torque which can be regulated by shunting individual strings to ground (52) or by opening a string circuit. This embodiment does not require the extra weight of a coil because the panel's solar string produces the torque normally produced by an additional coil. In another embodiment, a coil (44, 46)is wired between a shunting switch (54) in the spacecraft voltage controller (48) and a ground (32) so that shunting a string to ground (52) supplies current first to the coil to generate a magnetic torque in the desired direction.

Magnetic torque attitude control systems

Agile (electronically steerable) beam sensing with associated on-board processing, previously used exclusively for positioning of antennas for beam formation and tracking in communications systems, is now also used for satellite active attitude determination and control. A spinning satellite (100) is nadir oriented and precessed at orbit rate using magnetic torquing determined through use of an on-board stored magnetic field model (520) and attitude and orbit estimates (212). A Kalman filter (211) predicts parameters (202, 203) associated with a received signal (204) impinging on the satellite's wide angle beam antenna (201). The antenna system measures the error between the parameter predictions and observed values and sends appropriate error signals (207) to the Kalman filter for updating its estimation procedures. The Kalman filter additionally outputs the spacecraft attitude error signals (215) to an attitude control law (213), which determines commands to attitude-altering magnetic torque elements (220) to close the control loop via the spacecraft dynamics (230).

Satellite attitude determination and control system with agile beam

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Rancho Palos Verdes, CA, United States of America

Joseph H Hayden