USA-1 (satellite)

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Mission typeNavigation
OperatorUS Air Force
COSPAR ID1984-059A
SATCAT no.15039
Mission duration5 years (planned)
10 years (achieved)
Spacecraft properties
Spacecraft typeGPS Block I
Launch mass759 kilograms (1,673 lb)[1]
Start of mission
Launch date13 June 1984, 11:37 (1984-06-13UTC11:37Z) UTC
RocketAtlas E/F SGS-2, 42E[2]
Launch siteVandenberg SLC-3W[2]
End of mission
Deactivated20 June 1994 (1994-06-21)
Orbital parameters
Reference systemGeocentric
RegimeMedium Earth
Perigee altitude20,009 kilometres (12,433 mi)[3]
Apogee altitude20,354 kilometres (12,647 mi)[3]
Inclination62.5 degrees[3]
Period717.94 minutes[3]

USA-1, also known as Navstar 9, GPS I-9 and GPS SVN-9, was an American navigation satellite launched in 1984 as part of the Global Positioning System development programme. It was the ninth of eleven Block I GPS satellites to be launched,[1] and the first satellite to receive a USA designation.

USA-1 was launched at 11:37 UTC on 13 June 1984, atop an Atlas E/F carrier rocket with an SGS-2 upper stage. The Atlas used had the serial number 42E, and was originally built as an Atlas E.[2] The launch took place from Space Launch Complex 3W at Vandenberg Air Force Base,[4] and placed USA-1 into a transfer orbit. The satellite raised itself into medium Earth orbit using a Star-27 apogee motor.[1]

By 14 July 1984, USA-1 had been raised to an orbit with a perigee of 20,009 kilometres (12,433 mi), an apogee of 20,354 kilometres (12,647 mi), a period of 717.94 minutes, and 62.5 degrees of inclination to the equator.[3] The satellite had a design life of 5 years and a mass of 758 kilograms (1,671 lb).[1] It broadcast the PRN 13 signal in the GPS demonstration constellation, and was retired from service on 20 June 1994.


  1. ^ a b c d e Krebs, Gunter. "GPS (Navstar)". Gunter's Space Page. Retrieved 12 July 2012.
  2. ^ a b c McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved 12 July 2012.
  3. ^ a b c d e McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Page. Retrieved 12 July 2012.
  4. ^ McDowell, Jonathan. "Launch List". Launch Vehicle Database. Jonathan's Space Page. Retrieved 12 July 2012.