TAOS
Technology for Autonomous Operational Survivability

TAOS is a technology demonstration satellite whose purpose is to demonstrate autonomous space navigation systems to reduce satellite ground support needs. Lowering the needs for ground support of future spacecraft would 1) increase the survivability of satellites during wartime conditions and 2) reduce satellite operations costs. TAOS also incorporates several new satellite bus components designed to improve reliability and maintainability of future spacecraft while reducing life-cycle costs. TAOS is the first mission flown under the USAF's STEP (Space Test Experiments Platform) program, and is designated STEP Mission 0. The satellite is controlled from Onizuka AFB, Calif. Satellite operations were interrupted on July 19, 1994 when an inertial measurement unit failed. During the following two month period, the satellite's solar panels could not be properly sun-pointed, resulting in a loss of satellite power. Vehicle control was regained following the development of a new satellite control system.

Spacecraft
3-Axis stabilized. Two solar arrays with 1-axis articulation. Hydrazine propulsion system used for orbit maintenance and to desaturate momentum wheels. S-Band communications link with SGLS RTS stations. MIL-STD 1553B data bus used for intra-satellite communications. Two MIL-STD 175OA computers used for spacecraft control and payload operation.

Payload
10 experiments to investigate technologies applicable to autonomous space operations. Microcosm Autonomous Navigation System (MANS) used two spinning sensors to provide Earth/Sun/Moon position measurements to determine satellite position and attitude. The system had a goal of 100 meters in position and 0.03 degrees in attitude. A six-channel Global Positioning System (GPS) receiver was used to calculate orbital position to within several meters. The 1553B data bus and MIL-STD 175OA computers were carried as technology demonstrations. The satellite also carried a radar sensor and two laser sensors.

Country of Origin	United States
Customer/User	USAF
Manufacturer(s)	TRW, Defense Systems Inc. (now CTA)
Size	0.95 m dia. x 1.73 m tall (stowed)
Orbit	538 km, incl. = 105 deg.
Design Life	1 year
Related Sites	TAOS Page at Phillips Lab

Launch Facts

Name	Int'l Desig.	Date	Site	Vehicle	Orbit	Mass(kg)
Notes
STEP 0 (USA 101)	1994-017A	3/13/94	WSMC	Taurus	LEO	502
Space Test Experiment Program; 10 satellite subsystem experiments
Darpasat (TAOS, USA 102)	1994-017B	3/13/94	WSMC	Taurus	LEO	203
GPS receiver and data processor technology tests