|Operator||US Air Force|
|Mission duration||5 years (planned)|
11 years (achieved)
|Spacecraft type||GPS Block I|
|Launch mass||759 kilograms (1,673 lb)|
|Start of mission|
|Launch date||11 December 1978, 03:59UTC|
|Rocket||Atlas E/F SGS-1, 39F|
|Launch site||Vandenberg SLC-3E|
|End of mission|
|Perigee altitude||20,163 kilometres (12,529 mi)|
|Apogee altitude||20,201 kilometres (12,552 mi)|
OPS 5114, also known as Navstar 4, GPS I-4 and GPS SVN-4, was an American navigation satellite launched in 1978 as part of the Global Positioning System development programme. It was the fourth of eleven Block I GPS satellites to be launched.
OPS 5114 was launched at 03:59 UTC on 11 December 1978, atop an Atlas E/F carrier rocket with an SGS-1 upper stage. The Atlas used had the serial number 39F, and was originally built as an Atlas F. The launch took place from Space Launch Complex 3E at Vandenberg Air Force Base.
By 1 February 1979, OPS 5114 was in an orbit with a perigee of 20,163 kilometres (12,529 mi), an apogee of 20,201 kilometres (12,552 mi), a period of 717.96 minutes, and 63.2 degrees of inclination to the equator. The satellite had a design life of 5 years and a mass of 758 kilograms (1,671 lb). It broadcast the PRN 08 signal in the GPS demonstration constellation, and was retired from service on 14 October 1989. On 20 February 1990 it was reactivated for further testing, before being deactivated again in May 1990.
- "Navstar 4". US National Space Science Data Center. Retrieved June 25, 2012.
- Krebs, Gunter. "GPS (Navstar)". Gunter's Space Page. Retrieved July 12, 2012.
- McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved July 12, 2012.
- McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Page. Retrieved July 12, 2012.
- McDowell, Jonathan. "Launch List". Launch Vehicle Database. Jonathan's Space Page. Retrieved July 12, 2012.
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