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 (Template:Convert/round mi), an apogee of 20,474 kilometers (Template:Convert/round 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 (Template:Convert/round lb).  It is currently in service following commissioning on June 10, 2014.
- ↑ 1.0 1.1 Krebs, Gunter. "GPS-2F (Navstar-2F)". Gunter's Space Page. http://space.skyrocket.de/doc_sdat/navstar-2f.htm. Retrieved 17 May 2014.
- ↑ McDowell, Jonathan. "Launch Log". Jonathan's Space Page. http://planet4589.org/space/log/launchlog.txt. Retrieved 17 May 2014.
- ↑ McDowell, Jonathan. "Launch List". Launch Vehicle Database. Jonathan's Space Page. http://planet4589.org/space/lvdb/list2.html. Retrieved 17 May 2014.
- ↑ 4.0 4.1 McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Page. http://planet4589.org/space/log/satcat.txt. Retrieved 17 May 2014.
- ↑ "NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2014049". United States Coast Guard. http://www.navcen.uscg.gov/?Do=gpsShowNanu&num=2014049. Retrieved 11 June 2014.
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