Iridium Satellite LLC is the only provider of truly global mobile satellite voice and data solutions. With complete coverage of the Earth’s oceans, airways and Polar Regions, Iridium delivers essential services to users who need communications access to and from remote areas where no other form of communication is available. The company has operations in Leesburg, Virginia where the Satellite Network Operations Center is located, and gateway facilities in Tempe, Arizona and Oahu, Hawaii.
In December 2000, Iridium Satellite LLC acquired the operating assets of Iridium LLC including the satellite constellation, the terrestrial network, Iridium real property and intellectual capital. Headed by aviation industry veteran Dan Colussy, and funded by a group of private investors, Iridium Satellite LLC has essentially no debt and monthly operating charges that are one-tenth the cost of the previous Iridium. Through its own gateway in Hawaii, the U.S. Department of Defense relies on Iridium for global communications capabilities.
The Iridium System is a satellite-based, wireless personal communications network providing a robust suite of voice features to virtually any destination anywhere on earth.
The Iridium system comprises three principal components: the satellite network, the ground network and the Iridium subscriber products including phones and pagers. The design of the Iridium network allows voice and data to be routed virtually anywhere in the world. Voice and data calls are relayed from one satellite to another until they reach the satellite above the Iridium Subscriber Unit (handset) and the signal is relayed back to Earth.
The Iridium constellation consists of 66 operational satellites and 14 spares orbiting in a constellation of six polar planes. Each plane has 11 mission satellites performing as nodes in the telephony network. The 14 additional satellites orbit as spares ready to replace any unserviceable satellite. This constellation ensures that every region on the globe is covered by at least one satellite at all times.
The satellites are in a near-polar orbit at an altitude of 485 miles (780 km). They circle the earth once every 100 minutes traveling at a rate of 16,832 miles per hour. Each satellite is cross-linked to four other satellites; two satellites in the same orbital plane and two in an adjacent plane. The ground network is comprised of the System Control Segment and telephony gateways used to connect into the terrestrial telephone system. The System Control Segment is the central management component for the Iridium system. It provides global operational support and control services for the satellite constellation, delivers satellite tracking data to the gateways, and performs the termination control function of messaging services. The System Control Segment consists of three main components: four Telemetry Tracking and Control sites, the Operational Support Network, and the Satellite Network Operation Center. The primary linkage between the System Control Segment, the satellites, and the gateways is via K-Band feeder links and cross-links throughout the satellite constellation. Gateways are the terrestrial infrastructure that provides telephony services, messaging, and support to the network operations. The key features of gateways are their support and management of mobile subscribers and the interconnection of the Iridium network to the terrestrial phone system. Gateways also provide network management functions for their own network elements and links.
System improvements in the satellite and handset have been introduced, providing improved voice quality and subscriber equipment performance. The healthy satellite constellation is demonstrating outstanding longevity.