|Operator||US Air Force|
|Mission duration||7.5 years (planned)|
|Spacecraft type||GPS Block IIA|
|Launch mass||1,816 kilograms (4,004 lb)|
|Start of mission|
|Launch date||16 July 1996, 00:50:00UTC|
|Rocket||Delta II 7925-9.5, D237|
|Launch site||Cape Canaveral LC-17A|
|End of mission|
|Disposal||Placed in a graveyard orbit|
|Deactivated||11 March 2016|
|Perigee altitude||20,134 kilometres (12,511 mi)|
|Apogee altitude||20,227 kilometres (12,568 mi)|
USA-126, also known as GPS IIA-17, GPS II-26 and GPS SVN-40, is an American navigation satellite which forms part of the Global Positioning System. It was the seventeenth of nineteen Block IIA GPS satellites to be launched.
USA-126 was launched at 00:50:00 UTC on 16 July 1996, atop a Delta II carrier rocket, flight number D237, 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-126 into a transfer orbit. The satellite raised itself into medium Earth orbit using a Star-37XFP apogee motor.
On 15 August 1996, USA-126 was in an orbit with a perigee of 20,134 kilometres (12,511 mi), an apogee of 20,227 kilometres (12,568 mi), a period of 717.9 minutes, and 55 degrees of inclination to the equator. It broadcasts the PRN 10 signal, and operates in slot 3 of plane E of the GPS constellation. The satellite has a mass of 1,816 kilograms (4,004 lb). It had a design life of 7.5 years, however, it was kept in service for over 18 years before finally decommissioned from service on July 16, 2015.
Following decommissioning, it was subsequently placed in a disposal orbit approximately 1000 km above the operational constellation on March 11, 2016.