A warm wind just pushes your boat along at bare steerageway as water gurgles pleasantly in and out of the thru-hulls. You don’t mind the lackluster sailing performance because out here in the central Pacific, very far from human light, a preternatural vastness of ancient stars wheels slowly above you. Enjoying a sky show that landsmen almost never see, you loll in the cockpit, occasionally raising your head to check for other traffic on this peaceable, soulful night.A fiery rent appears in the fabric of the dome. Aha, you think, a solitary shooting star to underscore the transience of life set against the immutability of the heavens. But then another flaming track appears. In seconds, the sky is gouged by multiple burning lines. Your dreamy trance is shattered now. Sitting bolt upright, you stare with uneasy fascination at the threads of burning sky. An alien invasion? The advance scouts of a planet-killer asteroid about to send all life the way of the Tyrannosaurus? Some U.S. Defense Department missile test gone spectacularly awry? Only later do you discover the reason for the light show was the flickering destruction of the Iridium satellite communications system, a $5 billion corporate boondoggle by a consortium led by Motorola Corp.
The above account is a fiction, of course. While Iridium service officially ended on March 17, and Motorola issued an “urgent notice” that the system was to be completely turned off by August 31, the 90 or so satellites (66 plus 24 in-orbit spares) in 485-mile-high orbits are still whizzing around awaiting their fate. What will happen to this constellation of manmade moons? While Iridium’s business model was deeply flawed - the company never properly accounted for the worldwide explosion of wireless phone networks - its technology was superb.
Unlike most satellite systems that act as simple repeaters between ground stations, the so-called “bent pipe” model, Iridium’s hardware and software technology allowed it to relay phone calls between satellites, skipping the signals from bird to bird before sending them back down to Earth. Unfortunately for Iridium, cell phone towers sprouted across the landscape like a crop of steely mushrooms, and the average cell phone user is able to make a call for far less cost than can an Iridium subscriber. In addition to a lower cost per call, cell phones will also work inside buildings and cars, something Iridium phones just couldn’t do, given the need for the satellite to be in view of the phone. But back to the orphaned Iridium satellites. Why not simply leave them in place? After all, when the U.S. Navy shut down the Transit (usually referred to as satnav by sailors) satellite navigation system in the early 1990s (a victim of GPS), they actually launched a few satellites that were sitting in storage on the ground. Seems it was cheaper to put the birds in orbit than to keep paying the bill at the local space gear storage warehouse.
The Navy now has a group of satellites in polar orbits on standby status. (Standing by for what? A computer virus that fries the brains of GPS receivers?)The difference is that Iridium is a much larger constellation than Transit. All those satellites represent little more than space junk. The low-Earth-orbit (LEO) slots occupied by Iridium spacecraft are valuable real estate given all the satellites that are planned for launch in the next few years. There are a number of systems nearing launch status with more in the planning stages.You would expect space to live up to its name; there should be plenty of room up there. Even with all the opportunity for sprawl that space affords, however, the issue of “space junk” zipping around is a problem. The U.S. agency in charge of keeping track of all this space-age detritus is the United States Space Command (USSC), located in Colorado Springs, Colo.
According to Major Barry Venable, a Space Command spokesman, USSC is currently keeping track of more than 8,300 objects in orbit. These range from bits as small as 10 square centimeters to the twilight-viewable bulk of the Russian Mir space station. Since the Soviets launched Sputnik in 1957, Space Command has tracked more than 27,000 objects. The vast majority of these have either left orbit (think Apollo and Voyager) or reentered the atmosphere and burned up (remember Skylab’s fiery 1979 visit to Australia?).USSC tracks space objects for two reasons. “We need to make sure that nothing that’s reentering the atmosphere isn’t mistaken for an attacking missile,” said Venable. “We also perform tracking to aid in collision avoidance for spacecraft.” It’s this last aspect of the space junk question that argues for Iridium satellites to be de-orbited. Even though the risk of collision with other spacecraft by one of the Iridium craft is low, who needs 66 more potential hits complicating matters?So, according to Paul Dykewicz, editor of the trade publication Satellite News, “Motorola Inc. continues to work with federal regulators to finalize a plan to de-orbit the 66-satellites.” Offers from various entrepreneurs to buy the system and continue operations, including one reportedly brokered by the United Nations, have been rejected by Motorola as unacceptable.
Iridium’s satellites, representing an amazing technical achievement, will soon disappear in a few worldwide flashes of light. Even though Iridium is set to literally crash and burn, two other operating LEO satcom systems continue. Orbcomm, a 48-satellite “little LEO” system capable of sending short text messages worldwide, continues to serve customers. Orbcomm users can send and receive text messages from Internet e-mail addresses, making the system an extension of e-mail for voyagers. A big difference with Iridium is that Orbcomm is not a satellite phone system and cannot send voice.Globalstar, the other “big LEO” system that was a direct competitor to Iridium, continues to grow in billable minutes and customers. Its 52-satellite system is fully deployed in space. Like Iridium, Globalstar is a voice-based system with satellite phones that look like normal cell phones except for their oversized antennas.
For marine users, there is one important difference between Iridium and Globalstar. While Iridium satellites were able to relay conversations from spacecraft to spacecraft and then down to an earth station, Globalstar birds use the simpler “bent pipe” method. When the Globalstar satellites receive a call, they retransmit the call down to the nearest Earth station. If there is no Earth station in view, which would be the case for voyagers at sea, then a call would not be possible. Thus, Globalstar is only useful to mariners when they are in coastal areas.Other important systems still in the deployment stage are ICO and Teledesic. ICO started as a worldwide satellite phone effort by Inmarsat, the maritime satellite service. In the mid-1990s, Inmarsat spun off ICO as a separate unit. Since then, ICO was acquired by Craig McCaw’s ambitious satcom startup Teledesic. ICO is designed to use 10 satellites in medium Earth orbit (MEO), or about halfway between LEO and 23,000-mile-high geosynchronous (GEO) orbit. Like Globalstar, ICO will sell satellite telephones and offer voice service. Since ICO is backed by Inmarsat, one of the few organizations with years of experience actually operating a satcom system, some analysts believe it will be a serious competitor to Globalstar, even though it is starting later. The Teledesic system, meanwhile, was conceived as a swarm of 840 satellites that would provide broadband data, not voice, service worldwide - an Internet service provider in the sky. While Teledesic doesn’t plan to offer service to land mobile users, marine users will have a clear view to several satellites at once and should be able to use the system. Teledesic has since been redesigned to use 244 satellites. The first operational satellite launch is set for 2004.
While Iridium misjudged its market and went bust in spite of its superlative technology, that doesn’t mean satellite systems don’t make sense. They will be around for years to come, and voyagers will be using them.