Iridium global satcom system: Brilliant design, terrible business, last-minute reprieve, Part 1

This worldwide satellite-based communications system went from dream to reality in a decade but quickly failed in the market; its revival took persistence and luck, plus a new customer base.

Business failures of companies with grand schemes and grandiose plans are part of the realities of technology-driven visionaries. Sometimes, however, the project is so large and audacious that its evangelists misread harsh market realities despite astonishing technical success.

This was the case with the Iridium worldwide satellite-based communications system, a bold plan conceived in late 1987 by Bary Bertiger, Raymond J. Leopold, and Ken Peterson, engineers associated with Motorola (which holds the many Iridium patents). Though it is hard to put an exact price on the project, most estimates place the cost between $5 and $10 billion.

At the time, Motorola was among the worldwide leaders in wireless and wireless systems, providing basic voice radios, cellular infrastructure, and advanced systems to police, armed forces, and maritime users. They were a well-known, respected, and well-connected supplier in over 100 countries, with a reputation built over many decades. Without their financial investment and worldwide “influence,” Iridium would never have happened.

What Iridium is

Most people are so used to near-ubiquitous cellular connectivity that they may not fully realize that this is made possible by a cellular “backbone” network, which is invisible to the user. This network includes linked base stations and associated mobile telephone switching offices (MTSO) located as closely as needed to provide the cell coverage (a cell can range from a few blocks in span to tens of miles, depending on locale) (Figure 1). These MTSOs are linked to the base stations they directly serve and to each other and higher-level system management, usually via fiber-optic links or point-to-point microwave links, to manage and hand-off calls as the phone user moves from cell to cell.

The MTSO provides a critical behind-the-scenes function for the cellular phone system; it connects the nearby base stations to each other, to other MTSOs, and the existing landline telephone system. (Image: Tech-Faq)

The problem is that most of the Earth’s surface is covered with water and thus has no base stations or MTSOs; further, the maximum size of a base station is about 10 miles across (but many are far smaller, of course, and some are larger). There are also large, barely inhabited areas (the poles or deserts, for example), where base stations and MTSOs are not technically practical or financially viable; the Antarctic’s scientific stations are in this group.

The alternative to a cellular stem is conventional radio, but this has erratic connections due to atmospheric propagation issues, interference, electrical noise, and channel crowding due to too many users. Another possibility is a link to a geosynchronous satellite, but this has problems due to round-trip latency of about 250 msec and satellite visibility (which decreases as you get closer to either of Earth’s poles). There is a basic ship-to-shore radio and even a specialized satellite system (Inmarsat). Still, these are used primarily for low-rate weather updates, bulletins, or critical emergency messages, not ongoing, real-time conversations, and use carefully aimed dish antennas of about a meter diameter.

The Iridium system was designed to overcome all of the weaknesses of conventional radio, geosynchronous satellite links, geographical location, and travel while in use. The idea was to set up a system which would allow cellular-like connectivity (voice and even data) from anywhere on the globe—and they did mean anywhere.

The next part of this article looks at the plan and implementation of the Iridium system.

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External References