USA-50

USA-50, also known as GPS II-6 and GPS SVN-18, was an American navigation satellite which formed part of the Global Positioning System. It was the sixth of nine Block II GPS satellites to be launched, which were the first operational GPS satellites to fly.

USA-50 was launched at 22:55:01 UTC on 24 January 1990, atop a Delta II carrier rocket, flight number D191, flying in the 6925 configuration. The launch took place from Launch Complex 17A at the Cape Canaveral Air Force Station, and placed USA-50 into a transfer orbit. The satellite raised itself into medium Earth orbit using a Star-37XFP apogee motor.

On 25 February 1990, USA-50 was in an orbit with a perigee of 20087 km, an apogee of 20275 km, a period of 717.92 minutes, and 54.6 degrees of inclination to the equator. The satellite had a mass of 840 kg, and generated 710 watts of power. It had a design life of 7.5 years, and was retired from service on 18 August 2000.