Introduction to the History of Computing by Gerard O'Regan

Author:Gerard O'Regan
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

13.5 The Iridium Satellite System

Iridium was a global satellite phone company that was backed by Motorola. In many ways it was an engineering triumph over common sense, and over $5 billion was spent in building an infrastructure of low Earth orbit (LEO) satellites to provide global coverage. It was launched in the late 1998 to provide worldwide wireless coverage to its customers, and the coverage included the oceans, airways and polar regions. The existing telecom systems had limited coverage in remote areas, and so the concept of global coverage as provided by Iridium was potentially very useful.

Iridium was implemented by a constellation of 66 satellites (Fig. 13.4). The original design required 77 satellites, and so the name Iridium was chosen since its atomic number in the periodic table is 77. However, the later design required just 66 satellites, and so Dysprosium may have been a more appropriate name. The satellites are in low Earth orbit at a height of approximately 485 miles, and communication between the satellites is via inter-satellite links. Each satellite contains seven Motorola Power PC 603E processors running at 200 MHz. These machines are used for satellite communication and control.

Fig. 13.4Iridium system (Courtesy of Iridium)

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