BY DAN RALEY U.S. Army Special Forces soldier parachutes behind enemy lines and immediately sets his Global Positioning System watch for extraction. A farmer in the middle of Nebraska uses GPS to plow and plant the family acreage, plus check fertilizer distribution. GPS is essential for steering driver-less cars now in development. Following its launch last month from Cape Canaveral Air Force Station in Florida, the last of a dozen GPS Block IIF satellites, built by Boeing in El Segundo, Calif., aligned with 30 others to further bolster a navigational network that affects nearly every aspect of life on Earth. GPS makes the world a smaller place—over four decades, its accuracy in pinpointing a location has improved from 800 feet (250 meters) to fewer than 20 inches (50 centimeters), Boeing engineers say. “If you’re fortunate enough to have a smartphone or a receiver, you don’t get lost anymore; that’s not a part of life anymore,” said Eric Watts, Boeing GPS chief engineer in El Segundo. “You punch in where you want to go and you get there.” GPS is so ingrained in everyday activity that without it, mobile phones and the Internet would quit working or be disrupted, unable to locate transmission signals, according to Munzir Badawi, IIF program manager and acting manager for Civil programs. Financial transactions would ground to a halt, with automated teller machines unable to access time stamps. Aircraft operations would be curtailed, they note. “Boeing is one of the largest users of the GPS signal,” Badawi said. “Just about every product we provide, if intelligent, utilizes GPS of some sort.” The inclusion of the final IIF satellite in the orbiting constellation was bittersweet, a moment marked by the latest upgrade for GPS but also the end of a program line for Boeing. Lockheed Martin is under contract to build the next eight satellites for GPS IIIA, though production delays have reopened the door for the program bidding, and the Boeing GPS III team is developing a proposal for the next GPS program. Also, Boeing continues to support its existing fleet and focus on nextgeneration GPS technology—primarily the full-scale conversion from an analog to a digital satellite payload, or circuitry, similar to what took place with the modernization of standard telephones and televisions. This would lead to smaller satellites in size and weight, and the creation of small GPS payloads that could be hosted on other satellites, according to Dan Hart, vice president, Government Satellite Systems, Boeing Network & Space Systems. “That will allow a new flexibility never seen in the constellation,” Hart said. “It’s all eyes to the future.” Boeing has been connected to GPS since its inception, when heritage company Rockwell International launched the first navigational satellite in 1978 to support military activity only. Made available for civilian use five years later, the system now transmits geographic coordinates to more than 3 billion users worldwide, practically reversing its original directive. Twenty-four satellites, each equipped with multiple atomic clocks, are required to provide full coverage of Earth, with the seven additional orbiting vehicles used to fill in gaps or serve as backups. They travel 12,000 miles (20,000 kilometers) above the surface at 7,000 mph (11,300 kilometers per hour). They make two full passes around the planet each day. Schriever Air Force Base near Colorado Springs, Colo., houses the GPS master control station. Personnel from the 50th Space Wing operate A HOW GPS WORKS A Global Positioning System receiver uses at least three orbiting satellites to calculate a 2-dimensional position (latitude and longitude) and track movement. With four or more satellites, a receiver can determine a 3-D position (adding altitude). Once a user’s position has been pinpointed, information such as direction, speed, distance and distance to a destination becomes available. “The most important result of all of the calculations is that GPS gets us home safely to our families and keeps our nation and world secure,” said Mark Smith, GPS IIF engineering manager in El Segundo, Calif. GPS satellites circle Earth twice a day in a precise orbit, transmitting information to Earth. An estimated 3 billion users rely on the technology. Photo: A U.S. Air Force protective shroud encapsulates the last Boeing GPS IIF satellite before its launch in February. UNITED LAUNCH ALLIANCE MARCH 2016 | 27
Frontiers March 2016 Issue
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