USA-66

USA-66, also known as GPS IIA-1, GPS II-10 and GPS SVN-23, was an American navigation satellite which formed part of the Global Positioning System. It was the first of nineteen Block IIA GPS satellites to be launched, and was the oldest GPS satellite still in operation until its decommissioning on 25 January 2016.

USA-66 was launched at 21:39:01 UTC on 26 November 1990, atop a Delta II carrier rocket, flight number D201, flying in the 7925-9.5 configuration. The launch took place from Launch Complex 17A at the Cape Canaveral Air Force Station, and placed USA-66 into a transfer orbit. The satellite raised itself into medium Earth orbit using a Star-37XFP apogee motor.

On 30 December 1990, USA-66 was in an orbit with a perigee of 20072 km, an apogee of 20293 km, a period of 717.98 minutes, and 54.9 degrees of inclination to the equator. It was initially given PRN 23, which it used until its retirement in February 2004; however, it was subsequently reactivated broadcasting PRN 32 and in February 2008 it rejoined the operational constellation.

It is located in slot 5 of plane E of the GPS constellation. The satellite has a mass of 1816 kg. It had a design life of 7.5 years, but remained in service for over 25 years.

On 25 January 2016, USA-66 was decommissioned, and removed from the GPS constellation.