P91-1 ARGOS

The Advanced Research and Global Observation Satellite (ARGOS) was launched on 23 February 1999 carrying nine payloads for research and development missions by nine separate researchers. The mission terminated on 31 July 2003.

ARGOS was launched from SLC-2W, Vandenberg Air Force Base, California, atop a Boeing Delta II (7920-10) launch vehicle. Construction of the spacecraft bus and integration of the satellite's payloads was accomplished by Boeing at their Seal Beach, California facility. The program was funded and led by the DoD's Space Test Program (STP) as mission P91-1 (the first STP mission contract awarded in 1991).

The US$220 million mission was operated by Air Force Space Command's Space and Missile Systems Center's Test and Evaluation Directorate (then Space Development and Test Wing, now SMC's Advanced Systems and Development Directorate) from their RDT&E Support Complex (RSC) at Kirtland Air Force Base, New Mexico. ARGOS was the first mission operated 100% from the new state-of-the-art, commercial-off-the-shelf Kirtland facility; all previous SMC satellite missions had been operated in total or at least in part from the preceding center at Onizuka Air Force Station, California.

Mission

Colonel Tom Mead, program manager of the DoD Space Test Program, said of the satellite:

The ARGOS had a design life of three years and was part of the DoD Space Test Program (STP), which supports the Air Force, Army, Navy, BMDO (now MDA), NASA, and various international space agencies. The nine ARGOS payloads, addressing more than 30 research objectives, conducted upper atmospheric observations and technology demonstrations. These included sensor technology for the International Space Station (ISS), as well as three high-priority ultraviolet imaging experiments and an X-ray sensor. The remaining experiments investigate ion propulsion, gas ionization physics, plume detection capabilities, and orbital debris. As part of DOD STP, ARGOS served the need to fly Department of Defense payloads that cannot be flown on the Space Shuttle or aboard small launch vehicles due to complexity, size, mission duration, or other constraints. The Naval Research Laboratory (NRL), U.S. Army Space and Strategic Defense Command, Air Force Research Laboratory, and Office of Naval Research have provided payloads for the ARGOS mission.

Per the Kirtland AFB mission control center, "As of 1500 Zulu on 31 July 2003, support of all ARGOS operations has been terminated. Decaying inertial reference units has led to a tumble of the aircraft. As a result, communications with the spacecraft have been lost".

The satellite was designed to operate in a Sun-synchronous orbit and many of the payloads required unique Sun-angles, and so the orbit was creatively designed by Robert Cleave to operate without the need for an on-board propulsion subsystem, which was later identified as a key winning strategy.

Payloads

Will Hampton, Boeing director of U.S. Air Force Delta Programs, wrote:

Experiment (DOD Selective Experiments Review Board Year-Rank/Sponsor):

* CERTO - Coherent Electromagnetic Radio Tomography Experiment (1996-18/NRL) instrumentation: developed by NRL's Plasma Physics Division, consists of a stable radio beacon transmitter on the satellite and a chain of receivers on the ground. Radio transmissions from the CERTO beacon are processed by the ground receivers to produce two-dimensional maps of the electron densities in the ionosphere. The CERTO measurement technique provides images of the ionosphere with 10 km vertical and horizontal resolution. In addition, ionospheric irregularities of 1 km or less in size can be determined by fluctuations in the CERTO radio waves. CERTO can also be used to calibrate the ionospheric densities obtained using the EUV instruments such as HIRAAS, GIMI, and EUVIP on ARGOS. The CERTO radio-based technique has the advantage of higher spatial resolution than provided by the EUV-based techniques, but requires ground-based receivers aligned under the satellite orbit. The two techniques together on the same satellite provide substantial improvements over each technique separately. CERTO principal investigator, Dr. Paul Bernhardt notes that the NRL instruments on ARGOS was the first demonstration combining EUV and radio sensors for enhanced imaging of the ionosphere.
* CIV - Critical Ionization Velocity Experiment (1990-9/AFRL-Kirtland AFB): Release of xenon and carbon dioxide gases from nozzles on the ARGOS orbiting with a velocity of about 7.4 km/s at an altitude of about 800 km is proposed. The releases have been conducted mostly in darkness over the Maui telescope site. The vector sum of the satellite and gas velocities have exceeded the velocity requirement for the critical ionization velocity (CIV) process of xenon. It is feasible that the xenon gas will achieve critical velocity ionization. Ion source and collisional stripping will not occur for the xenon gas and there is no photo-ionization in darkness; ionization processes competing with CIV are absent. Neutral density, ambient magnetic field, and seed ionization effects on the xenon gas CIV will be discussed. Unlike xenon, carbon dioxide will not undergo CIV because of its higher velocity requirement. However, it is feasible that carbon dioxide colliding with the atmospheric species will form excited CO and OH molecules, which will radiate subsequently. Optical, IR, and UV observations on the satellite and at Maui Optical Telescope will provide diagnostic measurements for the experiment.
* ESEX - Electric Propulsion Space Experiment (1990-13/AFRL-Edwards AFB): an effort by the Air Force Research Laboratory's Propulsion Directorate (Edwards Air Force Base, California) demonstrated a high-powered electric propulsion provided by a 26 kilowatt ammonia fueled arcjet. Its use in space and evaluate its performance and interactions with other experiments and spacecraft systems on board a satellite. Through the ionizing of ammonia, ESEX's electric propulsion was expected to double the payload-to-orbit capability of current space propulsion systems. The ammonia propellant consumed was four times less than the best performing chemical rocket engine in use at that time. For the team, the best information gathered was the validation that firing the highest powered electric propulsion system in space did not interrupt telemetry or affect other equipment on the spacecraft.
* EUVIP - Extreme Ultraviolet Imaging Photometer Experiment (1990-8/Army Space & Strategic Defense Command): has established the behavior of the upper atmosphere and plasmasphere needed for Army secure communication systems design, prediction of magnetic storms, and characterization of the aurora.
* GIMI - Global Imaging Monitor of the Ionosphere Experiment (1990-19/NRL): will obtain wide-field FUV/EUV images of ionospheric and upper atmospheric emissions simultaneously, covering large areas of the Earth from a low Earth orbit. These images will be used to determine chemical densities O2, Nitrogen oxide">NO and Nitrogen dioxide">N2">Nitrogen_oxide.html" ;"title="Oxygen.html" ;"title="+, nighttime Oxygen">O2, Nitrogen oxide">NO and Nitrogen dioxide">N2on a global basis and to detect disturbances in the ionosphere that are caused by auroral activity, gravity waves and foreign materials from meteors, suspected "ice comets", rocket exhausts and chemical releases. In between the atmospheric observations, GIMI will also perform an all-sky survey of stars and celestial diffuse sources at Ultraviolet">far-ultraviolet