GPS Guidance System Development for the STARS Missile

E. Creel and A. Watts

Abstract:	The Strategic Target System (STARS) missile program is sponsored by the United States Army Space and Strategic Command (USASSDC) and is intended as a means of low cost target delivery to the Kwajelein Atoll area in support of the Ballistic Missile Defense Office (formerly SDIO) program objectives. The STARS missile is comprised of three rocket booster stages and an optional fourth-stage post-boost vehicle. The first and second stage motors consist of refurbished Polaris A3 assets whereas the third stage motor and post boost vehicle were newly designed specifically for the STARS program. STARS missiles are launched from Sandia’s Kauai Test Facility at Barking Sands, Kauai Hawaii. The first two STARS missions occurred in February and August of 1993. The STARS Mission-l (Ml) system which flew August 25,1993, included a development GPWnertial navigation system based on the Texas Instruments GPS embedded receiver module (GPSEM). This device was repackaged and interfaced to the STARS flight computer to provide simultaneous 1 Hz PR and PR-dot measurements for up to 6 SV’s. The GPSEM accepts high frequency inertial aiding data from the host allowing it to remain phase- locked to satellite signals during periods of high dynam- ics. All GPS measurement and associated filter data were down-linked for evaluation using S-band PCM telemetry. The guidance loop was not closed around the GPS-based error estimates since the accuracy of the stand-alone INS solution was adequate to satisfy the Ml mission objec- tives. The primary goal of the STARS GPS development activ- ity is to demonstrate that a GPS satellite signals continu- ously from launch to reentry, including the periods of high jerk and acceleration which accompany the ignition and thrusting of the rocket motors. Application of GPS receiver technology to the STARS missile system also offers the potential for providing very precise guidance and real-time metric scoring data at relatively low cost. The form-factor, weight, power consumption, and overall capability of this system is on the cutting edge of GPS technology. In-flight performance of the STARS Ml GPS system was outstanding. The receiver tracked SV’s all during the mission and also demonstrated the ability to reaquire SV signals masked during bus maneuvers. GPS system operation continued up to the time of reentry. At the time of loss of telemetry, the spent third stage was at about 240,000 feet altitude with a net velocity of just under 2O,OOOfr/s. The receiver was still tracking four SV’s and the onboard GPS Kalman filter was still converged and exhibiting small range and range-rate measurement re- siduals. Based on the results of the STARS Ml flight the future of GPS applied to the STARS ballistic missile looks bright. The STARS Ml mission demonstrated that indeed a closely-coupled INS/GPS system can be made to working periods of powered missile flights; and the immediate access to accurate metric scoring data that GPS provides is extremely valuable for timely post-flight assessments of mission performance parameters.
Published in:	Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993) September 22 - 24, 1993 Salt Palace Convention Center Salt Lake City, UT
Pages:	1441 - 1441
Cite this article:	Creel, E., Watts, A., "GPS Guidance System Development for the STARS Missile," Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993), Salt Lake City, UT, September 1993, pp. 1441-1441.
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