Space Superiority, Down to the Nanosecond: Why the Global Positioning System Remains Essential to Modern Warfare.

摘要

Reel back to the year 2008 when Michael Phelps swam into the history books with an astonishing finish to win his seventh gold medal by one one-hundredth of a second against Milorad Cavic. By any stretch of the imagination, the time differential in this historic race was imperceptible, but for the Global Positioning System (GPS) an error of one one-hundredth of a second would be a disaster.1 Why? For the GPS, one nanosecond (0.000000001 second) would result in the equivalent of approximately a one-foot error on Earth. Translated, Phelps s razor-thin margin of victory would have produced an incredible error of almost 10,000,000 feet or approximately 1,894 miles. Although the GPS provides so much more than just timing accuracy, this measurand has become one of its key hallmarks, as have its space superiority and force-multiplying capabilities. Joint Publication 3-14, Space Operations, defines space superiority, a primary focus of this article, as the degree of dominance in space of one force over any others that permits the conduct of operations at a given time and place without prohibitive interference from space-based threats (emphasis added).2 Although not yet fully operational at the time, the GPS was first used for combat in Operation Desert Storm, often called the first space war. 3 From initial air strikes by Pave Low helicopters to Gen Norman Schwarzkopf s famous left hook, the GPS served as a key force enabler, even with a very limited deployment of receivers.4 Furthermore, the GPS has been a crown jewel of the American military s superior space capabilities for decades, through Operation Enduring Freedom. Yet, emerging threats and increasingly sophisticated foreign capabilities present new challenges to maintaining US technical and operational advantages.