Iridium 77


Iridium 77
Iridium satellite.jpg
Iridium satellite, constructed entirely from spares and donated by Motorola to the National Air and Space Museum.
Mission typeCommunications
COSPAR ID1998-051E
SATCAT no.25471
Mission durationOngoing
Spacecraft properties
Spacecraft typeIridium
Start of mission
Launch dateSeptember 8, 1998, 21:13:00 (1998-09-08UTC21:13Z) UTC
RocketDelta II 7920-10C
Launch siteVandenberg SLC-2W
Orbital parameters
Reference systemGeocentric
RegimePolar Orbit
Periapsis altitude520 km
Apoapsis altitude540 km
Period95 minutes

Iridium 77 is a communications Satellite which is part of a satellite constellation known as Iridium, named after the 77th chemical element of the periodic table, iridium. It was launched in 1998 and as of 2014, operational. It is owned and funded by Iridium, a communications company.


Iridium 77 is a part of a space-based communications system called Iridium. Conceived, designed, and built by Motorola, the Iridium system provides wireless, mobile communications through a network of 66 satellites in polar, low-Earth orbits. Inaugurated in November 1998, under the auspices of Iridium LLC, this complex space system allowed callers using hand-held mobile phones and pagers to communicate anywhere in the world—a first in the history of telephony.



It was launched by Delta II 7920 from Vandenberg Air Force Base on 8 September 1998 at 21:13:00 UTC[1] along with four other satellites, all of which were Iridium satellites.


Iridium 77 is 3-axis stabilized, with a hydrazine propulsion system. It has 2 solar panels with 1-axis articulation. The system employs L-Band using FDMA/TDMA to provide voice at 4.8 kbit/s and data at 2.4 kbit/s with 16 dB margin. The satellite has 48 spot beams for Earth coverage and uses Ka-Band for crosslinks and ground commanding.[2]

See also


  1. ^ "Iridium 77". NASA. August 16, 2013. Retrieved March 30, 2014.
  2. ^ "Iridium 77". NASA. August 16, 2013. Retrieved March 30, 2014.