USA-94

Summary

USA-94
NamesNavstar 2A-13
GPS IIA-13
GPS II-22
GPS SVN-35
Mission typeNavigation
OperatorUS Air Force
COSPAR ID1993-054A [1]
SATCAT no.22779
Mission duration7.5 years (planned)
22.66 years (achieved)
Spacecraft properties
SpacecraftGPS IIA
Spacecraft typeGPS Block IIA[2]
ManufacturerRockwell International
Launch mass840 kg (1,850 lb)
Dimensions5.3 m (17 ft) of long
Power710 watts
Start of mission
Launch date30 August 1993, 12:38:00 UTC
RocketDelta II 7925-9.5
(Delta D222)
Launch siteCape Canaveral, LC-17B
Entered service1 October 1993
End of mission
DisposalGraveyard orbit
Deactivated10 June 2016
Orbital parameters
Reference systemGeocentric orbit[3]
RegimeMedium Earth orbit
(Semi-synchronous)
SlotB4 (slot 4 plane B)
Perigee altitude20,074 km (12,473 mi)
Apogee altitude20,221 km (12,565 mi)
Inclination54.9°
Period716.0 minutes
← USA-92 (GPS IIA-12)
USA-96 (GPS IIA-14) →
 

USA-94, also known as GPS IIA-13, GPS II-22 and GPS SVN-35, was an American navigation satellite which formed part of the Global Positioning System. It was the thirteenth of nineteen Block IIA GPS satellites to be launched.

Background

Global Positioning System (GPS) was developed by the U.S. Department of Defense to provide all-weather round-the-clock navigation capabilities for military ground, sea, and air forces. Since its implementation, GPS has also become an integral asset in numerous civilian applications and industries around the globe, including recreational used (e.g., boating, aircraft, hiking), corporate vehicle fleet tracking, and surveying. GPS employs 24 spacecraft in 20,200 km circular orbits inclined at 55.0°. These vehicles are placed in 6 orbit planes with four operational satellites in each plane.[1]

GPS Block 2 was the operational system, following the demonstration system composed of Block 1 (Navstar 1 - 11) spacecraft. These spacecraft were 3-axis stabilized, nadir pointing using reaction wheels. Dual solar arrays supplied 710 watts of power. They used S-band (SGLS) communications for control and telemetry and Ultra high frequency (UHF) cross-link between spacecraft. The payload consisted of two L-band navigation signals at 1575.42 MHz (L1) and 1227.60 MHz (L2). Each spacecraft carried 2 rubidium and 2 Cesium clocks and nuclear detonation detection sensors. Built by Rockwell Space Systems for the U.S. Air force, the spacecraft measured 5.3 m across with solar panels deployed and had a design life of 7.5 years.[1]

Launch

USA-94 was launched at 12:38:00 UTC on 30 August 1993, atop a Delta II launch vehicle, flight number D222, flying in the 7925-9.5 configuration.[4] The launch took place from Launch Complex 17B (LC-17B) at the Cape Canaveral Air Force Station (CCAFS),[5] and placed USA-94 into a transfer orbit. The satellite raised itself into medium Earth orbit using a Star-37XFP apogee motor.[2]

Mission

On 1 October 1993, USA-94 was in an orbit with a perigee of 20,074 km (12,473 mi), an apogee of 20,221 km (12,565 mi), a period of 716.0 minutes, and 54.9° of inclination to the equator.[3] It broadcast the PRN 30 signal, and operated in slot 4, and later 5, of plane B of the GPS constellation.[6] The satellite had a mass of 840 kg (1,850 lb) and a design life of 7.5 years.[2] It was initially decommissioned on 26 March 2009 and then kept as a residual satellite.[7] SVN 35 was then recalled to replace SVN 30 in the active constellation on 16 August 2011.[8][9]

It was then decommissioned again on 1 May 2013, after almost 20 years in orbit,[10] and finally placed in a disposal orbit approximately 1000 km above the operational constellation and deactivated on 10 June 2016.[11]

References

  1. ^ a b c "Display: Navstar 2A-13 1993-054A". NASA. 14 May 2020. Retrieved 20 December 2020. Public Domain This article incorporates text from this source, which is in the public domain.
  2. ^ a b c Krebs, Gunter. "GPS-2A (Navstar-2A)". Gunter's Space Page. Retrieved 10 July 2012.
  3. ^ a b "Trajectory: Navstar 2A-13 1993-054A". NASA. 14 May 2020. Retrieved 20 December 2020. Public Domain This article incorporates text from this source, which is in the public domain.
  4. ^ McDowell, Jonathan. "Launch Log". Jonathan's Space Report. Retrieved 10 July 2012.
  5. ^ McDowell, Jonathan. "Launch List". Launch Vehicle Database. Jonathan's Space Report. Retrieved 10 July 2012.
  6. ^ Wade, Mark. "Navstar". Encyclopedia Astronautica. Retrieved 10 July 2012.
  7. ^ "NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2009023". United States Coast Guard. Retrieved 23 June 2016. Public Domain This article incorporates text from this source, which is in the public domain.
  8. ^ "NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2011062". United States Coast Guard. Retrieved 23 June 2016. Public Domain This article incorporates text from this source, which is in the public domain.
  9. ^ "2SOPS Takes Over IIF-2, Moves to Replace SVN-30 with Spare". Inside GNSS. Retrieved 23 June 2016.
  10. ^ "NOTICE ADVISORY TO NAVSTAR USERS (NANU) 2013027". United States Coast Guard. Retrieved 3 May 2013. Public Domain This article incorporates text from this source, which is in the public domain.
  11. ^ "Obituary: Farewell to SVN-35". United States Air Force. Retrieved 23 June 2016. Public Domain This article incorporates text from this source, which is in the public domain.