Gauging variations in ocean temperature, currents and salinity, monitoring volcanic activity, measuring changes in Arctic sea ice, tracking wildlife migration and helping to manage shipping are just some of the applications supported by the Argos spaceborne location and data collection system, named after the 100-eyed Greek mythological giant Argus (Argos in French). The Argos system consists of radiotransmitters fitted on anything that needs to be tracked, from a boat or buoy to an animal, bird, cetacean, turtle or even a mountain peak. These radiotransmitters emit signals received by Argos instruments orbiting Earth on several satellites. The signals are recorded and then downlinked to a processing centre.

Instigated in 1978 by CNES and the U.S. National Oceanic & Atmospheric Administration (NOAA), Argos is today operated worldwide by CNES subsidiary CLS (Collecte Localisation Satellite). CNES is the Argos system architect and oversees development of its ground and space components. The spaceborne Argos instruments are built by Thales Airborne Systems (TAS).

Since 1978, there have been three generations of Argos instruments, launched on satellites operated by CNES’s partners: NOAA, and subsequently Eumetsat and ISRO, which both joined the programme in 2007. A fourth-generation instrument is set to enter service early in 2020. At the same time, CNES is also investing in the future and has developed a demonstrator called Argos-Neo, a miniaturized instrument built around commercial-off-the-shelf macro-components from the telecommunications market that will fly on the ANGELS nanosatellite planned for launch in October 2019.