I-4 satellite

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The Inmarsat-4 satellites, or I-4 satellites are a satellite constellation operated by Inmarsat.{{Cite web |title=ESA/Inmarsat agreement to improve satellite mobile phone and data services |url=https://www.esa.int/Applications/Connectivity_and_Secure_Communications/ESA_Inmarsat_agreement_to_improve_satellite_mobile_phone_and_data_services |access-date=2025-03-11 |website=ESA |language=en}}{{Cite web |title=Alphasat and the I-4s |url=https://www.inmarsat.com/about-us/about-usour-satellites/inmarsat-4/ |archive-url=https://web.archive.org/web/20180324040905/https://www.inmarsat.com/about-us/about-usour-satellites/inmarsat-4/ |archive-date=24 March 2018 |website=Inmarsat}} They provide the Inmarsat BGAN, FleetBroadband, and SwiftBroadband communications networks. They operate on the L band everywhere on Earth, except in polar regions.{{cite news|title=ESA and DARPA To Study Use of Inmarsat-4 for Space Data Relay|author=Peter B. de Selding |date=October 8, 2010 |url=https://spacenews.com/esa-and-darpa-study-use-inmarsat-4-space-data-relay/ |publisher=Space News |access-date=March 16, 2025}}

According to Inmarsat, their launch created the first global 3G mobile network.

The first three were launched between 2005 and 2008. They had a mass (at launch) of 5.96 tonnes, and were intended to last 13 years The dimensions of the main body comparable to a double-decker bus at 7m x 2.9m x 2.3m. Including the solar arrays, however, the wingspan is 45 meters, closer to the size of a soccer pitch. The reflectors are 9 meters wide.