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STEX (with ATEx attached) [Lockheed Martin]

The STEX (Space Technology Experiments) satellite carried 29 new technologies intended to result in lower cost and higher performance spacecraft for future missions. Among the technologies were Russian-derived Xenon Hall-effect electric thrusters capable of delivering 40 mN of thrust, a 51 Gbit solid-state data recorder, and high-density NiH batteries designed to last longer and provide more energy with less weight. ATEx (Advanced Tether Experiment), a 6 km tether with TiPS heritage, was to be deployed as a separate sub-satellite. Frangibolts were used on the mission for shockless deployment of the spacecraft and tether. Experimental solar panels with high-efficiency solar cells were also carried. The planned lifetime of STEX was two years.

The spacecraft was comprised of a body shell and two tracking solar panels. A blowdown liquid propulsion system was carried. The spacecraft was three-axis stablized. A lightweight precision star tracker was used to determine satellite pointing.

On 16 January 1999, ATEx was deployed, but failed. It was deployed but its two masses separated only by 22 m.

Nation: USA
Type / Application: Experimental
Operator: NRO
Contractors: Lockheed Martin Astronautics (Denver)
Equipment: ?
Configuration: ?
Propulsion: TAL-D55 plasma engine
Power: 2 deployable solar arrays, batteries
Mass: ?
Orbit: 750 km × 766 km, 85.0
Satellite COSPAR Date LS Launch Vehicle Remarks
STEX (USA 140, NROL 8) 1998-055A 03.10.1998 Va 576E Taurus-1110 with ATEx-UEB, ATEx-LEB