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Based on the navigation user range error, which measures GPS accuracy, the Block IIR satellites enable properly equipped users to determine precise time and velocity, and worldwide latitude, longitude and altitude to within one meter.
Lockheed Martin Space Systems, Valley Forge, Pa., is the prime contractor for the GPS IIR program. The company designed and built 21 IIR spacecraft for the Global Positioning Systems Wing, Space and Missile Systems Center, Los Angeles Air Force Base, Calif. The final eight spacecraft, designated Block IIR-M, were modernized to enhance operations and navigation signal performance for military and civilian GPS users around the globe. ITT, Clifton, N.J. supplied all 21 navigation payloads for both the IIR and IIR-M spacecraft.
"The improved performance of the GPS constellation is due in large part to the success of the Block IIR and IIR-M spacecraft series and a joint industry-government team dedicated to operational excellence and mission success," said Don DeGryse, Lockheed Martin's vice president of Navigation Systems. "We are proud to provide our customer with high-quality, high-value satellites that will continue to provide GPS users around the globe with enhanced navigation service for many years to come."
The GPS constellation provides critical situational awareness and precision weapon guidance for the military. The worldwide system also supports a wide range of civil, scientific and commercial functions - from air traffic control to the Internet - with precision location and timing information. The current fleet of Block IIR and IIR-M satellites within the overall GPS constellation has reached over 67 cumulative operational years on orbit.
The company is leveraging its proven record of building advanced global positioning system satellites for the next-generation system, known as GPS III. The Lockheed-led GPS III Space Segment team, which includes ITT and General Dynamics, is currently working under a Phase A Concept Development contract, with the Air Force expected to award a multi-billion dollar development contract to a single contractor in late 2007.
Source: GPS Daily, July 25, 2007.