OPS 5114

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.

Launch
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.

Orbit
OPS 5114 was placed into a transfer orbit. The satellite raised itself into medium Earth orbit using a Star-27 apogee motor.

By 1 February 1979, OPS 5114 was in an orbit with a perigee of 20163 km, an apogee of 20201 km, 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 kg. 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.