|Operator||US Air Force|
|Mission duration||7.5 years (planned)|
|Spacecraft type||GPS Block II|
|Launch mass||840 kilograms (1,850 lb)|
|Start of mission|
|Launch date||1 October 1990, 21:56:00UTC|
|Rocket||Delta II 6925, D199|
|Launch site||Cape Canaveral LC-17A|
|End of mission|
|Deactivated||14 March 2007|
|Perigee altitude||19,972 kilometres (12,410 mi)|
|Apogee altitude||20,390 kilometres (12,670 mi)|
USA-64, also known as GPS II-9 and GPS SVN-15, was an American navigation satellite which formed part of the Global Positioning System. It was the last of nine Block II GPS satellites to be launched, which were the first operational GPS satellites to fly. It was also the last Block II satellite to be retired from service.
USA-64 was launched at 21:56:00 UTC on 1 October 1990, atop a Delta II carrier rocket, flight number D199, flying in the 6925 configuration. The launch took place from Launch Complex 17A at the Cape Canaveral Air Force Station, and placed USA-64 into a transfer orbit. The satellite raised itself into medium Earth orbit using a Star-37XFP apogee motor.
On 31 October 1990, USA-64 was in an orbit with a perigee of 19,972 kilometres (12,410 mi), an apogee of 20,390 kilometres (12,670 mi), a period of 717.94 minutes, and 54.9 degrees of inclination to the equator. It operated in slot 5 of plane D of the GPS constellation. The satellite had a mass of 840 kilograms (1,850 lb), and generated 710 watts of power. It had a design life of 7.5 years, and ceased operations on 14 March 2007, having been removed from active service on 17 November 2006 for testing.