A Block IIF GPS satellite
|Operator||US Air Force|
|Mission duration||12 years (planned)|
|Spacecraft||GPS SVN-67 (IIF-6)|
|Spacecraft type||GPS Block IIF|
|Launch mass||1,630 kilograms (3,590 lb)|
|Start of mission|
|Launch date||17 May 2014, 00:03UTC|
|Rocket||Delta IV-M+(4,2), D365|
|Launch site||Cape Canaveral SLC-37B|
|Perigee altitude||20,443 km (12,703 mi)|
|Apogee altitude||20,474 km (12,722 mi)|
|Epoch||17 May 2014|
USA-251, also known as GPS IIF-6, GPS SVN-67 and NAVSTAR 70, is an American navigation satellite which forms part of the Global Positioning System. It was the sixth of twelve Block IIF satellites to be launched.
Built by Boeing and launched by United Launch Alliance, USA-251 was launched at 00:03 UTC on 17 May 2014, atop a Delta IV carrier rocket, flight number D366, flying in the Medium+(4,2) configuration. The launch took place from Space Launch Complex 37B at the Cape Canaveral Air Force Station, and placed USA-251 directly into medium Earth orbit.
As of 17 May 2014, USA-251 was in an orbit with a perigee of 20,443 kilometers (12,703 mi), an apogee of 20,474 kilometers (12,722 mi), a period of 729.22 minutes, and 55.04 degrees of inclination to the equator. It is used to broadcast the PRN 06 signal, and operates in slot 6 of plane D of the GPS constellation. The satellite has a design life of 15 years and a mass of 1,630 kilograms (3,590 lb).  It is currently in service following commissioning on June 10, 2014.