Iridium
What is Iridium?
- Iridium allows
users to connect and communicate anywhere on the planet, including areas
outside of terrestrial and cellular network coverage.
- Originally conceived in late 1987, Iridium was
developed by Motorola between 1993 and 1998.
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Garmin inReach devices use the Iridium satellite
network to provide users with world-wide access to communications and rescue
services.
Iridium Operation
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The Iridium constellation consists of 66 active
satellites (required for global coverage) with additional spares to
serve in case of failure.
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Iridium satellites send and receive data using L-Band frequencies in the
1610 - 1626 MHz range.
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The constellation of 66 active satellites has six
orbital planes spaced 30° apart, with 11 satellites in each plane (not
counting spares).
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Iridium Satellites operate in a low Earth orbit at
a height of approximately 485 mi (781 km) above MSL (mean sea level).
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Traveling at approximately 16,689 mph, each
Iridium satellite completes a full orbit of the Earth approximately once every
100 minutes.
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Reflecting light from the Sun, Iridium
satellites are frequently visible in the night sky as short-lived bright
flashes, known as Iridium flares:
Iridium Coverage
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The
original concept was to have 77 satellites, which is where the name Iridium
comes from, being the element with the atomic number 77 and the satellites
evoking the Bohr model image of electrons orbiting around the Earth as its
nucleus.
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Although
early calculations indicated 77 satellites would be required, the current
configuration of 66 satellites is sufficient to cover the entire Earth surface
at every moment.
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The
original Iridium constellation satellites were deployed between 1997 and
2002. No new satellites were launched to replenish the constellation over
the following 16 years, even though the original design had been projected
to have a life span of only 8 years.
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The second
generation Iridium NEXT system consist of 81 satellites:
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66
operational units
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9 in-orbit
spares
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6 ground
spares
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The NEXT satellites began deployment into the existing constellation in January
2017.
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Iridium
NEXT satellites incorporate features such as data transmission that were not
emphasized in the original design.
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The newer
Iridium NEXT system is backward-compatible with the original Iridium system.
a ten minute sample of Iridium satellite coverage
Iridium Availability
- Access to Iridium satellite services typically
requires an individual provider subscription.
- A SpaceX Falcon 9 rocket delivered the final
10 Iridium NEXT satellites into low earth orbit (LEO) on January 11th, 2019.
- The Iridium satellite constellation is unlike
any other in orbit and is the only communications network with pole-to-pole
coverage of the entire planet.
- Each Iridium satellite is cross-linked to four
others; two in the same orbital plane, and one in each adjacent plane,
allowing the network to 'hand off' traffic among satellites to ensure a
continuous connection with lower latency.
- Click anywhere on the map below to discover which
Iridium satellites are visible from the selected location.
- Select individual satellites to view detailed
information.
Iridium Satellite Constellation