Argos

ARGOS was the USAF Space Test Program P91-1 technology satellite by Boeing/Seal Beach. It carried an electric propulsion experiment, ionospheric instruments, a space dust experiment, and the NRL's USA hard X-ray astronomy detectors for X-ray binary star timing observations. ARGOS was built by Boeing/Seal Beach.

The ARGOS satellite was built by Space & Missile system Center (SMC), Los Angeles AFB, CA under the program P-91-1. ARGOS carried nine DoD space experiments to orbit, most notably the ESEX Arcjet thruster.

The ESEX (Electric Propulsion Space Experiment) program began in 1989 under the then Air Force Astronautics Lab, Edwards AFB, CA. The prime contractor was TRW, Space Park, Redondo Beach, CA. The Arcjet was build by Rocket Research (now Aerojet), Redmond, WA. The ESEX experiment flew once in 1999 on board the ARGOS satellite.

ESEX was the first High Power Electric Propulsion flight. The system operated on 30 kW with about 26 kW to the thruster. The experiment was powered by 205 kg of silver zinc batteries built by Eagle Pitcher Company of Joplin, Mo. At the time this was the highest power subsystem ever flown in space.

The objective was to verify Arcjet performance in space and determine if any spacecraft compatibility or contamination issues existed. AGROS operated with no detectable impact when the thruster operating. Sensors detected no RF interference, no increase in contamination, and measurements of specific impulse and thrust were within ground measurement uncertainty.

This truly pioneering flight program gave the satellite community great confidence in using High Power Electric propulsion.

Typical orbit: 832 km circular orbit, 98.8 deg inclination. Main Engine: ESEX Arcjet. Main Engine Thrust: 2.00 N (0.40 lbf). Main Engine Propellants: Electric/Ammonia. Main Engine Isp: 800 sec. Associated Launch Vehicle: Delta 7000.

• 1999 February 23 - ARGOS - Launch Site: Vandenberg. Launch Vehicle: Delta 7000. Perigee: 825 km (512 mi). Apogee: 839 km (521 mi). Inclination: 98.80 deg.

  ARGOS was a USAF Space Test Program P91-1 technology satellite, equipped with an ion engine, ionosphere, x-ray, and dust detectors. Much delayed, it finally was placed into orbit on the eleventh (!) launch attempt.

• McDowell, Jonathan, Jonathan's Space Report (Internet Newsletter), Harvard University, Weekly, 1989 to Present. Essential internet newsletter recording worldwide weekly space events. Accessed at: http://www.planet4589.org/jsr.html.