Mission typeNavigation
OperatorUS Air Force
COSPAR ID1990-025A
SATCAT no.20533
Mission duration7.5 years (planned)[1]
Spacecraft properties
Spacecraft typeGPS Block II[1]
Launch mass840 kilograms (1,850 lb)[2]
Start of mission
Launch date26 March 1990, 02:45:01 (1990-03-26UTC02:45:01Z) UTC
RocketDelta II 6925,[3] D193[3]
Launch siteCape Canaveral LC-17A[3]
End of mission
Deactivated13 December 1996 (1996-12-14)
Orbital parameters
Reference systemGeocentric
RegimeMedium Earth
Perigee altitude20,089 kilometres (12,483 mi)[4]
Apogee altitude20,268 kilometres (12,594 mi)[4]
Inclination55 degrees[4]
Period717.84 minutes[4]

USA-54, also known as GPS II-7 and GPS SVN-20, was an American navigation satellite which formed part of the Global Positioning System. It was the seventh of nine Block II GPS satellites to be launched, which were the first operational GPS satellites to fly.

USA-54 was launched at 02:45:01 UTC on 26 March 1990, atop a Delta II carrier rocket, flight number D193, flying in the 6925 configuration.[3] The launch took place from Launch Complex 17A at the Cape Canaveral Air Force Station,[5] and placed USA-54 into a transfer orbit. The satellite raised itself into medium Earth orbit using a Star-37XFP apogee motor.[1]

On 30 April 1990, USA-54 was in an orbit with a perigee of 20,089 kilometres (12,483 mi), an apogee of 20,268 kilometres (12,594 mi), a period of 717.84 minutes, and 55 degrees of inclination to the equator.[4] The satellite had a mass of 840 kilograms (1,850 lb), and generated 710 watts of power.[2] It had a design life of 7.5 years,[1] however following problems with the satellite switching between timing standards, the satellite was declared unusable on 21 May 1996,[6] and was decommissioned on 13 December.


  1. ^ a b c d e Krebs, Gunter. "GPS-2 (Navstar-2)". Gunter's Space Page. Retrieved 10 July 2012.
  2. ^ a b "Navstar 2-07". US National Space Science Data Center. Retrieved 10 July 2012.
  3. ^ a b c d McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved 10 July 2012.
  4. ^ a b c d e 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.