Argos is a global

satellite A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scient ...

-based system that collects, processes, and disseminates (spreads, distributes) environmental data from fixed and mobile platforms around the world. The worldwide tracking and

environmental monitoring Environmental monitoring is the processes and activities that are done to characterize and describe the state of the environment. It is used in the preparation of environmental impact assessments, and in many circumstances in which human activit ...

system is the results fro
Franco-American cooperation.
In addition to satellite data collection, the main feature of the Argos system is its to ability to geographically locate the data source from any location on

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

using the

Doppler effect The Doppler effect (also Doppler shift) is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave. The ''Doppler effect'' is named after the physicist Christian Doppler, who described ...

; which refers to the apparent change in the

wavelength In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats. In other words, it is the distance between consecutive corresponding points of the same ''phase (waves ...

due to relative motion between its source and observer. Argos is operated by CLS/Argos, based in

Toulouse Toulouse (, ; ; ) is a city in southern France, the Prefectures in France, prefecture of the Haute-Garonne department and of the Occitania (administrative region), Occitania region. The city is on the banks of the Garonne, River Garonne, from ...

, France, and its United States subsidiary, CLS America.

History and utilization

Argos was established in 1978 and has provided data to environmental research and protection groups. It is a component of many global research programs including the Tropical Ocean-Global Atmosphere program (TOGA), Tagging of Pacific Pelagics (TOPP), World Ocean Circulation Experiment (WOCE) and,

Argo In Greek mythology, the ''Argo'' ( ; ) was the ship of Jason and the Argonauts. The ship was built with divine aid, and some ancient sources describe her as the first ship to sail the seas. The ''Argo'' carried the Argonauts on their quest fo ...

. There are 22,000 active transmitters (8,000 of which are used in animal tracking) in over 100 countries. Since the late 1980s, Argos transmitters have been deployed on a large number of marine mammals and sea turtles, and it is used for tracking long-distance movements of both coastal and oceanic species. Argos was developed under a Memorandum of Understanding (MOU) between the Centre National d'Études Spatiales (

CNES CNES () is the French national space agency. Headquartered in central Paris, the agency is overseen by the ministries of the Armed Forces, Economy and Finance and Higher Education, Research and Innovation. It operates from the Toulouse Spac ...

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

), the National Aeronautics and Space Administration (

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

) and the National Oceanic and Atmospheric Administration (

NOAA The National Oceanic and Atmospheric Administration (NOAA ) is an American scientific and regulatory agency charged with forecasting weather, monitoring oceanic and atmospheric conditions, charting the seas, conducting deep-sea exploratio ...

, United States). The system utilizes both ground and satellite-based resources to accomplish its mission. These include: * instruments carried aboard the NOAA Polar Operational Environmental Satellites (POES), the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Metop satellites, and

Indian Space Research Organisation The Indian Space Research Organisation (ISRO ) is India's national List of government space agencies, space agency, headquartered in Bengaluru, Karnataka. It serves as the principal research and development arm of the Department of Space (DoS), ...

(ISRO) satellites, * receiving stations around the world * major processing facilities in

in France and

Lanham, Maryland Lanham is an unincorporated community and census-designated place in Prince George's County, Maryland. As of the 2020 United States census, it has a population of 11,282. The New Carrollton station (the terminus of the Washington Metro's O ...

in the United States. Since June 2019, a new subsidiary named Kinéis has taken over operations and plans to launch a constellation of 16U

CubeSat A CubeSat is a class of small satellite with a form factor of cubes. CubeSats have a mass of no more than per unit,, url=https://static1.squarespace.com/static/5418c831e4b0fa4ecac1bacd/t/5f24997b6deea10cc52bb016/1596234122437/CDS+REV14+2020-07-3 ...

s in 2022. In June 2024, the first of these Cubesats were launched on a

Rocket Lab Electron Electron is a two-stage, partially reusable launch vehicle, reusable orbital launch vehicle developed by Rocket Lab, an American aerospace company with a wholly owned New Zealand subsidiary. Servicing the commercial small satellite launch market ...

launch vehicle named "No Time Toulouse". On 20 September 2024, the second batch of five Cubesats were launched on electron launch number 53 named "Kinéis Killed The RadIoT Star", see List of Electron launches.

Operating agencies

The Argos satellite-based system was set up by: * The

Centre National d'Études Spatiales CNES () is the French national space agency. Headquartered in central Paris, the agency is overseen by the ministries of the Armed Forces, Economy and Finance and Higher Education, Research and Innovation. It operates from the Toulouse Spac ...

(CNES). * The U.S.

National Oceanic and Atmospheric Administration The National Oceanic and Atmospheric Administration (NOAA ) is an American scientific and regulatory agency charged with Weather forecasting, forecasting weather, monitoring oceanic and atmospheric conditions, Hydrography, charting the seas, ...

(NOAA). * The U.S.

National Aeronautics and Space Administration The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the United States's civil space program, aeronautics research and space research. Established in 1958, it su ...

(NASA). Recent partners in this international cooperative venture are: * The European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). * The

(ISRO).

Frequencies and data transfer

Most use of the Argos System makes use of one-way data transmission on 401.65 MHz using Argos 2. Each Argos platform features a unique 28-bit ID and the ability to transmit a short 3 to 31 byte message for each transmission. Each platform is restricted to a specified interval, such as every 60 seconds, allowing for a few hundred bytes total per satellite pass. This is enough to contain a couple elements of

geographic coordinates A geographic coordinate system (GCS) is a spherical or geodetic coordinate system for measuring and communicating positions directly on Earth as latitude and longitude. It is the simplest, oldest, and most widely used type of the various ...

or other sensor data. Argos 1 is no longer supported. In order to determine transmitter position using Doppler shift on a single satellite accurately, approximately 4-6 transmissions are required in succession during a satellite pass. Accuracy can vary between several hundred meters to several kilometers. The Argos 3 system uses a downlink signal at 465.9875 MHz. However, due to ground-based alarm system interference issues in the United States, the downlink was disabled on the NOAA-19 satellite. Other newer satellites still transmit on this frequency. The downlink contains date and time, Argos System satellite ephemeris data, and the downlink portion of the two-way communication link. Data collected from the Argos System is transmitted to the ground using two possible methods. If an Argos System ground receiving station is in view of the satellite while the transmitter is also in view, the data is transmitted and processed in near real time. If a ground station is not in view or operational, data is additionally transmitted from the satellite to one of several polar based ground stations. This introduces additional delay in receiving messages.

Satellite constellation

The Argos System is served by 9 polar orbiting satellites at an altitude of 850 km and completes a revolution around

approximately every 100 minutes. At a vantage point of 850 km, satellites cover approximately 5000 km² of Earth. Each satellite was intended to be

Sun-synchronous A Sun-synchronous orbit (SSO), also called a heliosynchronous orbit, is a nearly polar orbit around a planet, in which the satellite passes over any given point of the planet's surface at the same local mean solar time. More technically, it is ...

, with passes almost at the same solar time each day. Although, due to the age of some satellites, minor drifting does occur. Due to the satellite constellations polar orbit, 100% of the Earth is covered by the Argos System. Since pass overlap increase with latitude, the number of daily passes over a transmitter also increase with latitude.

References

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External links