Solar Pointing Attitude Rocket Control System /SPARCS/

The SPARCS system is described and its use since Dec. 1967 is reviewed. SPARCS was developed to fulfill a requirement for a lightweight, precision, three-axis pointing control system for solar-sounding rockets. The use of sounding rockets to calibrate satellite instruments before flight for subsequent recovery and orbital flight is noted, along with the calibration of Skylab instruments with sounding rocket payloads. The gyroless SPARCS weights under 36 lb, is 6 in. in diam, and is self-contained regarding electronics, pneumatics, gas supply, electrical power, and coarse solar sensors. A two-axis sensor measures pitch and yaw error relative to the solar vector, and functions by pointing the longitudinal axis toward the radiometric center of the sun. Pointing errors cause voltages which activate pneumatic valves, allowing miniature gas jets to zero the pointing error. SPARCS has been used successfully on 100 missions.