|Start of mission|
|Launch date||September 8, 1998, 21:13:00UTC|
|Rocket||Delta II 7920-10C|
|Launch site||Vandenberg SLC-2W|
|Periapsis altitude||520 km|
|Apoapsis altitude||540 km|
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.
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.