National Aeronautics and Space Administration

ARGOS (USA)

The Advanced Research and Global Observations Satellite (ARGOS) was a satellite funded out of the U.S. Department of Defence Space Test Program and operated by the U.S. Air Force. The mission was launched on 23 Feb 1999, and operations continued until 31 July 2003. Note that this is not the same mission as the Argos System, a series of NOAA satellites.

Mission Overview

ARGOS was launched from Vanguard Air Force Base on a Delta II rocket, and operated by the Air Force’s Research, Development, Test and Evaluation Support Complex (RSC) at Kirkland Air Force Base. The satellite carried nine different instruments, each associated with different research groups with different agencies. The satellite was placed in a sun-synchronous roughly circular polar orbit at an altitude of 833 kilometres. Operations were ceased on 31 July 2003.

Instrumentation

ARGOS carried nine different instruments, though only one of relevance to high-energy astrophysics:

• The Unconventional Stellar Aspect (USA) instrument (also known by the less memorable name “NRL-801 experiment”) was a Naval Research Lab instrument to observe bright x-ray sources. It consisted of a pair of large-area gas scintillation proportional counters sensitive to 1–15 keV mounted on a two-axis pointing system. It was a reflight of the SPARTAN 1 instrument flown on the Space Shuttle Discovery in June 1985. USA included precise (roughly microsecond accuracy) time-tagging of events using an integrated GPS receiver. The USA instrument operated from May 1, 1999 through November 16, 2000.