About Iridium
The nitty gritty.
Iridium has the world's only truly global commercial satellite network. Learn
why. 
The Iridium constellation consists of 66 low-earth orbiting (LEO), cross-linked
satellites operating as a fully meshed network. That's more satellites than any
other constellation and it's the largest commercial satellite constellation in
the world. This is what makes the Iridium network unique. Several overlapping
satellites ensure the globe is covered. An independent study found Iridium's network to have
the best call quality and call completion rates over other similar competitors.
This is one of the many reasons the U.S. military relies on the Iridium
network.
The on-orbit Iridium constellation consists of 66 operational satellites and 14
spares 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 travelling
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. These links create a dynamic network in space - calls are
routed among Iridium satellites without touching the ground, creating a highly
secure and reliable connection. Cross-links make the Iridium network
particularly impervious to natural disasters - such as hurricanes, tsunamis and
earthquakes - that can damage ground-based wireless towers.
The ground network is comprised of the System Control Segment and gateways to
the terrestrial networks. The System Control Segment is what commands and
controls the satellites for the Iridium system. It provides global operational
support and control services for the satellite constellation. It also delivers
satellite tracking data to the gateways. It 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 through a satellite to
satellite communications system called K-Band feeder links and cross-links
throughout the satellite constellation.
The existing satellite constellation is expected to provide continuous global
coverage until 2014. Find out what Iridium is doing
NEXT.