The nearly polar orbit and communication between satellites via Ka band inter-satellite links provide global service availability (including both poles, oceans and airways), regardless of the position of ground stations and gateways.

This resulted in a phenomenon called Iridium flares, whereby the satellite momentarily appeared as one of the brightest objects in the night sky and could be seen even during daylight.

The over-the-pole orbital design produces "seams" where satellites in counter-rotating planes next to one another are traveling in opposite directions.

[1] Iridium SSC employed a globally diverse fleet of rockets to get their 77 satellites into orbit, including launch vehicles (LVs) from the United States, Russia, and China.

Poor reception from inside buildings, bulky and expensive handsets, and competition with the conventional cellular phone contributed to its failure.

[10] Insufficient market demand existed for the product at the price points on offer from Iridium as set by its parent company Motorola.

The company failed to earn revenue sufficient to service the debt associated with building out the constellation and Iridium went bankrupt, one of the largest bankruptcies in US history at the time.

[1] In August 2008, Iridium selected two companies — Lockheed Martin and Thales Alenia Space — to participate in the final phase of the procurement of the next-generation satellite constellation.

In June 2010, the winner of the contract was announced as Thales Alenia Space, in a $2.1 billion deal underwritten by Compagnie Française d'Assurance pour le Commerce Extérieur.

[11] Iridium additionally stated that it expected to spend about $800 million to launch the satellites and upgrade some ground facilities.

[15] The satellites each contained seven Motorola/Freescale PowerPC 603E processors running at roughly 200 MHz,[16] connected by a custom backplane network.

Late in the project an extra processor ("SAC") was added to perform resource management and phone call processing.

The configuration of the Satellite concept was designated as Triangular Fixed, 80 Inch Main Mission Antenna, Light-weight (TF80L).

The TF80L configuration was considered a non-conventional, innovative approach to developing a satellite design that could be assembled and tested in five days.

The TF80L design configuration was also instrumental in simultaneously solving fundamental design problems involving optimization of the communications payload thermal environment and RF main mission antenna performance, while achieving the highest payload fairing packaging for each of the three main launch vehicle providers.

The first spacecraft mock-up of this design was built in the garage workshop in Santa Clara, California for the Bus PDR/CDR as a proof-of-concept model.

The Earth's equatorial bulge causes the orbital right ascension of the ascending node (RAAN) to precess at a rate that depends mainly on the period and inclination.

[28] The NEXT satellites incorporate a secondary payload for Aireon,[29] a space-qualified ADS-B data receiver for use by air traffic control and, via FlightAware, by airlines.

[30] A tertiary payload on 58 satellites is a marine AIS ship-tracker receiver for Canadian company ExactEarth Ltd.[31] In January 2020, the Iridium constellation was certified for use in the Global Maritime Distress and Safety System (GMDSS).

The certification ended a monopoly on the provision of maritime distress services that had previously been held by Inmarsat since the system became operational in 1999.

[26] In June 2010, Iridium signed the largest commercial rocket-launch deal ever at that time, a US$492 million contract with SpaceX to launch 70 Iridium NEXT satellites on seven Falcon 9 rockets from 2015 to 2017 via SpaceX leased launch facility at Vandenberg Air Force Base.

This second launch, which occurred on June 25, 2017, delivered another ten Iridium NEXT satellites to low Earth orbit (LEO) on a SpaceX Falcon 9 rocket.

[46][non-primary source needed] Over the years a number of Iridium satellites have ceased to work and are no longer in active service, some are partially functional and have remained in orbit whereas others have tumbled out of control or have reentered the atmosphere.

In 1999, Iridium agreed to timeshare a portion of spectrum, allowing radio astronomers to observe hydroxyl emissions.

[56][57] External "hockey puck" type antennas used with Iridium handheld phones, data modems and SBD terminals are usually defined as 3 dB gain, 50 ohms impedance with RHCP (right hand circular polarization) and 1.5:1 VSWR.

As a satellite travels over the ground location, calls are handed to adjacent spot-beams; this occurs approximately every fifty seconds.

The space-based backhaul routes outgoing phone call packets through space to one of the ground station downlinks ("feeder links").

Iridium ground stations interconnect the satellite network with land-based fixed or wireless infrastructures worldwide to improve availability.

[68] In 2024, Iridium introduced Project Stardust, a 3GPP standard-based satellite-to-cellphone service focusing on messaging, emergency communications and IoT for devices like cars, smartphones, tablets and related consumer applications.

Scheduled for launch in 2026, it won't replace the company's proprietary solution for voice and high-speed data; instead it will co-exist with that offering on the Iridium's existing global low-earth orbit satellite network.