ცოდნა სინათლეა - Knowledge is light - Знание свет -  

                                 GPS Block III

                                                   Artist's impression of a GPS Block III satellite in orbit

(previously Block IIIA) consists of the first ten GPS III satellites, which will be used to keep the Navstar Global Positioning System operational. Lockheed Martin designed, developed and manufactured the GPS III Non-Flight Satellite Testbed (GNST) and all ten Block III satellites.^[8] The first satellite in the series was launched in December 2018. The tenth and final GPS Block III launch is projected in 2023.

Block III satellites use Lockheed Martin's A2100M satellite bus structure. The propellant and pressurant tanks are manufactured by Orbital ATK from lightweight, high-strength composite materials. Each satellite will carry eight deployable JIB antennas designed and manufactured by Northrop Grumman Astro Aerospace

Already delayed significantly beyond the first satellite's planned 2014 launch, on 27 April 2016, SpaceX, in Hawthorne, California, was awarded a US$82.7 million firm-fixed-price contract for launch services to deliver a GPS III satellite to its intended orbit. The contract included launch vehicle production, mission integration, and launch operations for a GPS III mission, to be performed in Hawthorne, California; Cape Canaveral Air Force Station, Florida; and McGregor, Texas.In December 2016, the Director of the U.S. Air Force's Global Positioning Systems Directorate announced the first satellite would launch in the spring of 2018. In March 2017, the U.S. General Accounting Office stated "Technical issues with both the GPS III satellite and the OCX Block 0 launch control and checkout system have combined to place the planned March 2018 launch date for the first GPS III satellite at risk". The delays were caused by a number of factors, primarily due to issues found in the navigation payload. Further launch date slippages were caused by the need for additional testing and validation of a SpaceX Falcon 9 which ultimately launched the satellite on 23 December 2018.On 22 August 2019, the second GPS III satellite was launched aboard a Delta IV.

Future Block III variants are planned to incorporate additional capabilities. They include Distress Alerting Satellite System (DASS) capabilities for search and rescue, as well as satellite crosslinks for rapid command and reduced age of data.On 21 September 2016, the U.S. Air Force exercised a US$395 million contract option with Lockheed Martin for the ninth and tenth Block III space vehicles, expected to be available for launch by 2022.

The FY 2021 Department of Defense budget allocates US$1.8 billon for 2 GPS III systems for the United States Space Force.

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იხ. ბმულზე       https://shotashota75.blogspot.com/2020/06/blog-post_3.html