USA-71

USA-71

Mission type	Navigation
Operator	US Air Force
COSPAR ID	1991-047A[1]
SATCAT №	21552[1]
Mission duration	7.5 years (planned)[2]
Spacecraft properties
Spacecraft type	GPS Block IIA[2]
Manufacturer	Rockwell[2]
Launch mass	1,816 kilograms (4,004 lb)[2]
Start of mission
Launch date	4 July 1991, 02:32:00 UTC
Rocket	Delta II 7925-9.5,[3] D206[3]
Launch site	Cape Canaveral LC-17A[3]
Orbital parameters
Reference system	Geocentric
Regime	Medium Earth (Semi-synchronous)
Perigee	20,085 kilometres (12,480 mi)[4]
Apogee	20,274 kilometres (12,598 mi)[4]
Inclination	55.1 degrees[4]
Period	717.86 minutes[4]

USA-71, also known as GPS IIA-2, GPS II-11 and GPS SVN-24, is an American navigation satellite which forms part of the Global Positioning System. It was the second of nineteen Block IIA GPS satellites to be launched.

USA-71 was launched at 02:32:00 UTC on 4 July 1991, atop a Delta II carrier rocket, flight number D206, flying in the 7925-9.5 configuration.^[3] The launch took place from Launch Complex 17A at the Cape Canaveral Air Force Station,^[5] and placed USA-71 into a transfer orbit. The satellite raised itself into medium Earth orbit using a Star-37XFP apogee motor.^[2]

On 14 August 1991, USA-71 was in an orbit with a perigee of 20,085 kilometres (12,480 mi), an apogee of 20,274 kilometres (12,598 mi), a period of 717.86 minutes, and 55.1 degrees of inclination to the equator.^[4] It has PRN 24, and operated in slot 1 of plane D of the GPS constellation^[6] until it was removed from service in September 2009. It was subsequently relocated, was operational again, briefly covering slot 2 in 2011, before being deactivated in November after USA-232 replaced it. It began transmitting navigation signals again in March 2012; however, it is not currently part of the operational GPS constellation.^[7] The satellite has a mass of 1,816 kilograms (4,004 lb), and a design life of 7.5 years.^[2]

References

1. "Navstar 2A-02". US National Space Science Data Center. Retrieved 10 July 2012.
2. Krebs, Gunter. "GPS-2A (Navstar-2A)". Gunter's Space Page. Retrieved 10 July 2012.
3. McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved 10 July 2012.
4. McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Page. Retrieved 10 July 2012.
5. McDowell, Jonathan. "Launch List". Launch Vehicle Database. Jonathan's Space Page. Retrieved 10 July 2012.
6. Wade, Mark. "Navstar". Encyclopedia Astronautica. Retrieved 10 July 2012.
7. "NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2012018". US Air Force. Retrieved 10 July 2012.