Iridium 77

Iridium 77
	Iridium satellite, constructed entirely from spares and donated by Motorola to the National Air and Space Museum.
Mission type	Communications
Operator	Iridium
COSPAR ID	1998-051E
SATCAT no.	25471
Mission duration	19 years
Spacecraft properties
Spacecraft type	Iridium
Manufacturer	Motorola
Start of mission
Launch date	September 8, 1998, 21:13:00 UTC
Rocket	Delta II 7920-10C
Launch site	Vandenberg SLC-2W
Contractor	Iridium
Orbital parameters
Reference system	Geocentric
Regime	Polar Orbit
Eccentricity	0.00145
Periapsis altitude	520 km
Apoapsis altitude	540 km
Inclination	86°
Period	95 minutes
Epoch	1998-09-08

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

Network

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.

Overview

Launch

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.

Features

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]