GPS Declassified: From Smart Bombs to Smartphones by Richard D. Easton and Eric F. Frazier (review)

In just a quarter-century, GPS has evolved from an amazing high-tech military system that helped U.S. troops navigate with pinpoint accuracy across a featureless desert during Operation Desert Storm to a standard feature in smartphones that not only tells us where we are, but enables “enhanced reality” apps to lead us to the best restaurants, cheapest gas, or cleanest restrooms based on our current location. GPS, short for the Navstar Global Positioning System, uses a network of satellites to provide worldwide navigation information free of charge to anyone who can afford a receiver. It guides airplanes and ships through darkness and fog, permits farmers to optimize their use of seed and fertilizer, and allows the military to deliver “smart bombs” with unprecedented precision. Its orbiting atomic clocks provide the standardized global time stamp used to manage data flow on the World Wide Web. But how does it work? And how did it come to be? These are the questions that Richard D. Easton and Eric F. Frazier explore in GPS Declassified: From Smart Bombs to Smartphones.

Easton and Frazier trace the origins of GPS (officially authorized in 1973 and fully operational some two decades later) to U.S. efforts to track the first artificial satellites, including Sputnik, which the Soviet Union launched in 1957. Early systems used multiple ground-based stations (at known locations) to pinpoint satellites (the unknown location). At its simplest, GPS works in reverse, using signals sent from satellites orbiting at known locations overhead to determine the receiver’s position on the ground, at sea, or in the air. The book also reveals that GPS was not the first satellite navigation system. For instance, a network called Transit, employed by the military starting in 1964 and opened to commercial use in 1967, allowed ships and submarines to determine their location within 500 feet, worldwide, in any weather.

The authors, independent writers whose past articles on science and technology targeted technical or popular audiences, are at their best when describing complex technology in understandable everyday terms. They also effectively use anecdotes and case studies to illustrate various points in the development and widespread adoption of GPS, from the story of a Naval Research Laboratory engineer who in 1964 drove down an unfinished highway carrying a transmitter in his convertible to test a prototype system (p. 50), to the “full dress rehearsal” of the new GPS satellite network during the 1990–91 Persian Gulf War (p. 125), to the poignant case of a young family that became snowbound on Christmas Eve in 2009 because they unquestioningly followed a “shortcut” suggested by their brand-new GPS unit and drove onto an unplowed logging road in the Oregon mountains (pp. 155–56).

The book is not without faults. The usually clear, engaging prose becomes mired in detail when describing government debates, past and present, regarding funding for, and access to, space-based navigational systems. The same is true of chapter 3, “Success Has Many Fathers,” but for a different reason. Coauthor Easton’s father, Roger Easton, developed much of the technology and conceptual framework behind GPS during his long career at the U.S. Naval Research Laboratory. However, because the air force was given the lead for deploying the system and still runs it today, that branch is often credited with inventing GPS by itself. Richard Easton has labored for years researching and publishing articles regarding his father’s actual role, and chapter 3 reflects this in-depth knowledge, painstakingly laying out who said or wrote what, when, and to whom in various memos, official reports, briefing slides, and interviews. Although this is a crucial part of the GPS story, the authors could have made this chapter as readable as the rest of the book by relegating some of the details to the endnotes.

Easton and Frazier conclude by discussing the future of satellite navigation, offering...