USA-54
| Names | Navstar 2-07 GPS II-7 GPS SVN-20 |
|---|---|
| Mission type | Navigation |
| Operator | U.S. Air Force |
| COSPAR ID | 1990-025A |
| SATCATno. | 20533 |
| Mission duration | 7.5 years (planned) 6.5 years (achieved) |
| Spacecraft properties | |
| Spacecraft | GPS II |
| Spacecraft type | GPS Block II[1] |
| Manufacturer | Rockwell International[1] |
| Launch mass | 840 kg (1,850 lb)[2] |
| Dimensions | 5.3 m (17 ft) of long |
| Power | 710 watts |
| Start of mission | |
| Launch date | 26 March 1990, 02:45:01UTC |
| Rocket | Delta II 6925-9.5 (Delta D193)[3] |
| Launch site | Cape Canaveral,LC-17A |
| Contractor | McDonnell Douglas |
| Entered service | April 1990 |
| End of mission | |
| Deactivated | 21 May 1996 |
| Orbital parameters | |
| Reference system | Geocentric orbit[4] |
| Regime | Medium Earth orbit (Semi-synchronous) |
| Slot | ? |
| Perigee altitude | 20,089 km (12,483 mi) |
| Apogee altitude | 20,268 km (12,594 mi) |
| Inclination | 55.0° |
| Period | 717.84 minutes |
USA-54,also known asGPS II-7andGPS SVN-20,was an Americannavigation satellitewhich formed part of theGlobal Positioning System.It was the seventh of nineBlock IIGPS satellites to be launched, which were the first operational GPS satellites to fly.
Background
[edit]Global Positioning System (GPS) was developed by theU.S. Department of Defenseto 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.[2]
GPS Block 2 was the operational system, following the demonstration system composed of Block 1 (Navstar 1 - 11) spacecraft. These spacecraft were3-axis stabilized,nadirpointing usingreaction wheels.Dual solar arrays supplied 710 watts of power. They usedS-band(SGLS) communications for control and telemetry andUltra high frequency(UHF) cross-link between spacecraft. The payload consisted of twoL-bandnavigation signals at 1575.42MHz(L1) and 1227.60 MHz (L2). Each spacecraft carried 2rubidiumand 2Cesiumclocks and nuclear detonation detection sensors. Built byRockwell Space Systemsfor 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.[2]
Launch
[edit]USA-54 was launched at 02:45:01 UTC on 26 March 1990, atop aDelta IIlaunch vehicle,flight number D193, flying in the 6925-9.5 configuration.[3]The launch took place fromLaunch Complex 17A(LC-17A) at theCape Canaveral Air Force Station(CCAFS),[5]and placed USA-54 into a transfer orbit. The satellite raised itself intomedium Earth orbitusing aStar-37XFPapogee motor.[1]
Mission
[edit]On 30 April 1990, USA-54 was in an orbit with aperigeeof 20,089 km (12,483 mi), anapogeeof 20,268 km (12,594 mi), aperiodof 717.84 minutes, and 55.0° ofinclinationto theequator.[4]The satellite had a mass of 840 kg (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]
References
[edit]
- ^abcdKrebs, Gunter."GPS-2 (Navstar-2)".Gunter's Space Page.Retrieved10 July2012.
- ^abcd"Display: Navstar 2-07 1990-025A".NASA. 14 May 2020.Retrieved18 December2020.
This article incorporates text from this source, which is in thepublic domain.
- ^abMcDowell, Jonathan."Launch Log".Jonathan's Space Report.Retrieved10 July2012.
- ^abMcDowell, Jonathan."Satellite Catalog".Jonathan's Space Report.Retrieved10 July2012.
- ^McDowell, Jonathan."Launch List".Launch Vehicle Database.Jonathan's Space Report. Archived fromthe originalon 15 August 2020.Retrieved10 July2012.
- ^Wade, Mark."Navstar".Encyclopedia Astronautica. Archived fromthe originalon 11 November 2002.Retrieved10 July2012.