USA-50
American navigation satellite used for GPS
title: "USA-50" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["gps-satellites", "usa-satellites", "spacecraft-launched-in-1990"] description: "American navigation satellite used for GPS" topic_path: "general/gps-satellites" source: "https://en.wikipedia.org/wiki/USA-50" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary American navigation satellite used for GPS ::
::data[format=table title="Infobox spaceflight"]
| Field | Value |
|---|---|
| name | USA-50 |
| names_list | Navstar 2-06 |
| GPS II-6 | |
| GPS SVN-18 | |
| image_size | 290px |
| mission_type | Navigation |
| operator | U.S. Air Force |
| COSPAR_ID | 1990-008A |
| SATCAT | 20452 |
| mission_duration | 7.5 years (planned) |
| 10.5 years (achieved) | |
| spacecraft | GPS II |
| spacecraft_type | GPS Block II |
| manufacturer | Rockwell International |
| launch_mass | 840 kg |
| dimensions | 5.3 m of long |
| power | 710 watts |
| launch_date | 24 January 1990, 22:55:01 UTC |
| launch_rocket | Delta II 6925-9.5 |
| (Delta D191) | |
| launch_site | Cape Canaveral, LC-17A |
| launch_contractor | McDonnell Douglas |
| entered_service | February 1990 |
| deactivated | 18 August 2000 |
| orbit_reference | Geocentric orbit |
| orbit_regime | Medium Earth orbit |
| (Semi-synchronous) | |
| orbit_slot | ? |
| orbit_periapsis | 20087 km |
| orbit_apoapsis | 20275 km |
| orbit_inclination | 54.6° |
| orbit_period | 717.92 minutes |
| apsis | gee |
| programme | Global Positioning System |
| previous_mission | USA-49 (GPS II-5) |
| next_mission | USA-54 (GPS II-7) |
| :: |
| name = USA-50 | names_list = Navstar 2-06 GPS II-6 GPS SVN-18 | image = | image_caption = | image_size = 290px
| mission_type = Navigation | operator = U.S. Air Force | COSPAR_ID = 1990-008A | SATCAT = 20452 | mission_duration = 7.5 years (planned) 10.5 years (achieved)
| spacecraft = GPS II | spacecraft_type = GPS Block II | manufacturer = Rockwell International | launch_mass = 840 kg | dimensions = 5.3 m of long | power = 710 watts
| launch_date = 24 January 1990, 22:55:01 UTC | launch_rocket = Delta II 6925-9.5 (Delta D191) | launch_site = Cape Canaveral, LC-17A | launch_contractor = McDonnell Douglas
| entered_service = February 1990 | disposal_type = | deactivated = 18 August 2000
| orbit_reference = Geocentric orbit | orbit_regime = Medium Earth orbit (Semi-synchronous) | orbit_slot = ? | orbit_periapsis = 20087 km | orbit_apoapsis = 20275 km | orbit_inclination = 54.6° | orbit_period = 717.92 minutes | apsis = gee
| programme = Global Positioning System | previous_mission = USA-49 (GPS II-5) | next_mission = USA-54 (GPS II-7) USA-50, also known as GPS II-6 and GPS SVN-18, was an American navigation satellite which formed part of the Global Positioning System. It was the sixth of nine Block II GPS satellites to be launched, which were the first operational GPS satellites to fly.
Background
It was part of the 21-satellite Global Positioning System (GPS) Block II series that provides precise position data (accurate to within 16 m) to military and civilian users worldwide. Its signals could be received on devices as small as a telephone. The GPS II satellites, built by Rockwell International for the Air Force Space Systems Division, each have a 7.5-year design life. The Air Force intends to launch a GPS II every 2 to 3 months until the constellation of 21 operational satellite and 3 spares is aloft. The GPS Block II join 7 operational Block 1 satellites.
Launch
USA-50 was launched at 22:55:01 UTC on 24 January 1990, atop a Delta II launch vehicle, flight number D191, flying in the 6925-9.5 configuration. The launch took place from Launch Complex 17A (LC-17A) at the Cape Canaveral Air Force Station (CCAFS), and placed USA-50 into a transfer orbit. The satellite raised itself into medium Earth orbit using a Star-37XFP apogee motor.
Mission
On 25 February 1990, USA-50 was in an orbit with a perigee of 20087 km, an apogee of 20275 km, a period of 717.92 minutes, and 54.6° of inclination to the equator. The satellite had a mass of 840 kg, and generated 710 watts of power. It had a design life of 7.5 years, and was retired from service on 18 August 2000.
References
References
- McDowell, Jonathan. "Launch Log". Jonathan's Space Report.
- McDowell, Jonathan. "Launch List". Jonathan's Space Report.
- Krebs, Gunter. "GPS-2 (Navstar-2)". Gunter's Space Page.
- McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Report.
- "Display: Navstar 2-06 1990-008A". NASA.
::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::