1998

Iridium Satellite System

Barry Bertiger (Dates Unavailable), Dr. Ray Leopold (Dates Unavailable), Ken Peterson (Dates Unavailable)

The architecture of the current cell phone system is an example of engineering genius because of the way it optimizes things. By placing cell phone towers in a grid every few miles, it is possible for the phones to contain low-power transmitters that never need to send signals more than a mile or two. Low-power transmitters mean small size and low battery drain, meaning that a cell phone can fit in your pocket.

The towers-in-grid approach does have one drawback—it becomes economically unfeasible in places with low population density. Towers are expensive, and they can’t be deployed unless there are enough people using them to recover the cost.

The Iridium system, owned by Iridium Communities Inc. in Virginia, asked the question: How do we provide cell phone coverage to all of the places that lack towers? The answer that Motorola engineers Barry Bertiger, Dr. Ray Leopod, and Ken Peterson came up with was amazing in scope—they would use dozens of satellites to provide planetwide coverage. Their system, conceived in 1987, became commercially available in 1998.

A satellite in geosynchronous orbit requires a stationary dish antenna because it is 24,000 miles (38,000 km) away. Iridium engineers wanted something far more portable and mobile. So they conceived of a constellation of satellites in low-Earth orbit, approximately 500 miles (800 km) overhead. At that altitude, there would need to be a lot of satellites so a phone would be guaranteed to always have a satellite in range. In fact, the number of satellites needed is 66, plus some spares. The satellites talk to each other so that conversations can route through a satellite-based mesh network to a ground station.

While the engineering is spectacular, this architecture has problems. Transmitting to a satellite 500 miles away requires a lot more power, so the phones are bigger, with bigger antennas and a high price tag. It also requires line-of-sight, meaning the phones have difficulty inside buildings. The system’s price tag of $5 billion led to high-priced calls. Very few people signed up, and Iridium went bankrupt in 1999, though the system was purchased and still operates today.

SEE ALSO Telephone (1876), Space Satellite (1957), ARPANET (1969), Mobile Phone (1983), Lithium Ion Battery (1991), Smart Phone (2007).

An Inuit hunter using an Iridium satellite phone on the Melville Peninsula, Nunavut, Canada.