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Program: Inmarsat

INternational MARitime SATellite

Inmarsat was created by the International Maritim Organization (dependent of the United Nations) on 16 Jul 1979. It is based in London and started working on 1 Feb 1982. Inmarsat must provide links between maritime mobiles and ground networks using geostationary satellites. The services are telephone, telex, fax and an access to the emergency system Sarsat/Cospas.

Inmarsat's structure is close to Intelsat's one. It isn't dominated by the United States which enabled USSR to join in.

The organization gathered 48 members in 1986 and 64 in 1991. The first operational system opened in 1985. Transponders were leased on 6 satellites: Marisat, Marecs and Intelsat. With the success encountered Inmarsat decided in 1983 to operate its own satellites.

Over 20 ground stations have been installed and in 1992 over 15000 terminals had been sold. The states that mostly participate in the funding are the United States, Norway, the UK and Japan.
Inmarsat is also working on aeronautical links and a project of personnal communication medium. Inmarsat might develop low orbit satellites on polar orbits to cover Northern and Southern regions.

Inmarsat was privatized in March 1999. An intergovernmental body called International Mobile Satellite Organization (IMSO) was created to manage the public service obligations (mainly the Global Maritime Distress and Safety System (GMDSS)). The rest of the activities are held by a private entity (IPO in June 2005).

The fourth generation satellites introduced in 2005 provides internet links (BGAN) at up-to 432 kbps.

Inmarsat 5 generation (global Xpress): 3 Ka-band satellites were ordered from Boeing in mid-2010 (1 additional in Oct 2013 for a cost between $220 and $250 million). 702 HP-based. 89 beams. Options include 2 other satellites. To be delivered in 36-months. Cost is estimated at $1.2 billion over 4.5 years, including launch services and ground segment. First launch in 2013 on Proton.

In Jun 2017 a new satellite called Inmarsat GX5 (we will call it Inmarsat 5F5) was ordered from Thales Alenia Space to cover the Middle East, Europe and the Indian subcontinent, worth $130 million.

In Jun 2019, the company placed an order with Airbus for 3 Ka-band satellites, based on the new OneSat range which is reconfigurable in orbit. Features onboard processing and active antennas to adjust their coverage, capacity and frequency. First launch planned in 2023, now 2026. [for the moment they are called GX7, 8, 9, S3060 to S3063]

The program was acquired by Viasat in Nov 2021 and approved by the UK in Sep 2022.

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