GPS Block I
Launch of Navstar 1, the first GPS Block I satellite
View full image ↗ How was this image made?
The creative brief sent to the image model. These are instructions, not a record of what actually happened.
Original prompt & settings (JSON) ↗The date in this event's own slug is five days late. Navstar 1 left Vandenberg on 22 February 1978.
22 February, not 27
The U.S. Air Force launched Navstar 1 from Vandenberg Air Force Base, California, on an Atlas F booster. Official Air Force and Space Force histories date the launch to 22 February 1978.
The 27 February date carried in the supplied slug and listing is erroneous.
One developmental spacecraft
Rockwell International's Space Division built and tested Navstar 1 at Seal Beach, California, as the first developmental Block I Navstar/GPS spacecraft, also designated SVN-1.
It was the first purpose-built Block I GPS satellite. Earlier Navigation Technology Satellites had supported GPS development, and NTS-2 had transmitted the first true GPS signals in 1977.
Not a service, a test program
The launch started the GPS space-segment test program with an actual Block I satellite in orbit. It created no operational worldwide service that day.
Three more Navstar launches followed in 1978, and satellites 1 through 4 were set healthy on 8 January 1979 as the first four-satellite test configuration. Of eleven Block I launch attempts through 1985, ten spacecraft reached orbit.
Sources
Researched 23 Aug 2026 5 sources 2 audit passes Date corrected
How this was checked
Researched from the web into a fact sheet, rewritten from that sheet, then audited against it by a different model. How the pipeline works →
Date corrected. The research places this at 1978-02-22.
What the sources leave uncertain
- The launch date is not genuinely disputed: February 22, 1978 is supported by official Air Force and Space Force histories and contemporary reporting. The February 27 date embedded in the supplied slug and listing is erroneous.
- Earlier Navigation Technology Satellites supported GPS development, and NTS-2 transmitted the first true GPS signals in 1977. Navstar 1 is best described as the first purpose-built Block I GPS satellite, not the first navigation or positioning satellite of any kind.