GPS satellite blocks
satellite used by the NAVSTAR Global Positioning System (GPS)
GPS satellite blocks are the various production generations of the Global Positioning System (GPS) used for satellite navigation. The first satellite in the system, Navstar 1, was launched by the United States Air Force on 22 February 1978. The GPS satellite constellation is now operated by the 2nd Navigation Warfare Squadron (2 NWS) of Mission Delta 31, United States Space Force.
The GPS satellites circle the Earth at an altitude of about 20,000 km (12,427 miles) and complete two full orbits every day.
Satellites by block
Block I satellites
Rockwell International was awarded a contract in 1974 to build the first eight Block I satellites. In 1978, the contract was extended to build an additional three Block I satellites. Beginning with Navstar 1 in 1978, ten "Block I" GPS satellites were successfully launched. One satellite, "Navstar 7", was lost due to an unsuccessful launch on 18 December 1981.
The Block I satellites were launched from Vandenberg Air Force Base using Atlas rockets that were converted intercontinental ballistic missiles. The satellites were built by Rockwell International at the same plant in Seal Beach, California where the S-II second stages of the Saturn V rockets were built.
The public source identifies “GPS satellite blocks” as satellite used by the NAVSTAR Global Positioning System (GPS). This brief keeps that definition visible, then builds a research path around satellite, blocks and used.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated May 26, 2026. The linked authority identifier is Q1069313. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1978, 1974 and 1981.
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This entry incorporates text from “GPS satellite blocks” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.