Following the successful operation of the Tether Physics and Survivability (TiPS) satellite (June 1996 to the present), the Naval Center for Space Technology (NCST) designed and built the Advanced Tether Experiment (ATEx). ATEx had three mission objectives:
- Demonstrate tether system stability and control
- Demonstrate end-body attitude determination and control
- Fly a tether designed for survivability
ATEx was hosted on the Space Technology Experiment (STEX) satellite. STEX was injected into planned orbit on October 3, 1998 from Vandenberg, California on board a Taurus rocket. Taurus injected into approximately a 370 NM altitude, 85 degree inclination, near circular orbit. STEX is in its mission orbit of about 406 NM circular altitude.
The ATEx deployment began 16 January 1999 at 23:06 UT and ended 18 minutes later. The ATEx tether pair was jettisoned from the STEX spacecraft after deploying only 22 meters. The jettison was triggered by an automatic protection system designed to save STEX if the tether began to stray from its expected departure angle. The failure is currently being investigated.