USA-117
{{Short description|American navigation satellite used for GPS}}
{{Use American English|date=December 2020}}
{{use dmy dates|date=December 2020}}
{{Infobox spaceflight
| name = USA-117
| names_list = Navstar 2A-16
GPS IIA-16
GPS II-25
GPS SVN-33
| image =
| image_caption =
| image_size = 290px
| mission_type = Navigation
| operator = U.S. Air Force
| SATCAT = 23833
| mission_duration = 7.5 years (planned)
18.25 years (achieved)
| spacecraft = GPS IIA
| spacecraft_type = GPS Block IIA
| manufacturer = Rockwell International
| launch_mass = {{cvt|840|kg}}
| dimensions = {{cvt|5.3|m}} of long
| power = 710 watts
| launch_date = 28 March 1996, 00:21:00 UTC
| launch_rocket = Delta II 7925-9.5
(Delta D234)
| launch_site = Cape Canaveral, LC-17B
| launch_contractor = McDonnell Douglas
| entered_service = 27 April 1996
| disposal_type = Graveyard orbit
| deactivated = 2 August 2014
| orbit_reference = Geocentric orbit
| orbit_regime = Medium Earth orbit
(Semi-synchronous)
| orbit_slot = C2 (slot 2 plane C)
| orbit_periapsis = {{cvt|20078|km}}
| orbit_apoapsis = {{cvt|20282|km}}
| orbit_inclination = 54.70°
| orbit_period = 718.00 minutes
| apsis = gee
| programme = Global Positioning System
| previous_mission = USA-100 (GPS IIA-15)
| next_mission = USA-126 (GPS IIA-17)
}}
USA-117, also known as GPS IIA-16, GPS II-25 and GPS SVN-33, is an American navigation satellite which forms part of the Global Positioning System. It was the sixteenth 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.{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1996-019A|title=Display: Navstar 2A-16 1996-019A|publisher=NASA|date=14 May 2020|access-date=20 December 2020}} {{PD-notice}}
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.
Launch
USA-117 was launched at 00:21:00 UTC on 28 March 1996, atop a Delta II launch vehicle, flight number D234, flying in the 7925-9.5 configuration.{{cite web |url=http://planet4589.org/space/log/launchlog.txt|title=Launch Log|publisher=Jonathan's Space Report|first=Jonathan|last=McDowell|access-date=11 July 2012}} The launch took place from Launch Complex 17B (LC-17B) at the Cape Canaveral Air Force Station (CCAFS),{{cite web|url=http://planet4589.org/space/lvdb/list2.html|title=Launch List|publisher=Jonathan's Space Report|work=Launch Vehicle Database|first=Jonathan|last=McDowell|access-date=11 July 2012|archive-date=15 August 2020|archive-url=https://web.archive.org/web/20200815040340/http://planet4589.org/space/lvdb/list2.html|url-status=dead}} and placed USA-117 into a transfer orbit. The satellite raised itself into medium Earth orbit using a Star-37XFP apogee motor.{{cite web |url=http://space.skyrocket.de/doc_sdat/navstar-2a.htm|title=GPS-2A (Navstar-2A)|first=Gunter|last=Krebs|publisher=Gunter's Space Page|access-date=10 July 2012}}
Mission
On 27 April 1996, USA-117 was in an orbit with a perigee of {{cvt|20078|km}}, an apogee of {{cvt|20282|km}}, a period of 718.00 minutes, and 54.70° of inclination to the equator.{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/displayTrajectory.action?id=1996-019A|title=Trajectory: Navstar 2A-16 1996-019A |publisher=NASA|date=14 May 2020|access-date=20 December 2020}} {{PD-notice}} It broadcasts the PRN 03 signal, and operates in slot 2 of plane C of the GPS constellation.{{cite web |url=http://www.astronautix.com/project/navstar.htm|archive-url=https://web.archive.org/web/20021111162023/http://www.astronautix.com/project/navstar.htm|url-status=dead|archive-date=11 November 2002|title=Navstar|publisher=Encyclopedia Astronautica|first=Mark|last=Wade|access-date=10 July 2012}} The satellite has a mass of {{cvt|840|kg}}. It had a design life of 7.5 years; however, it actually remained in service until 2 August 2014.
It was subsequently disposed of and currently resides in a disposal orbit approximately 500 km above the operational constellation.{{cite web|url=http://www.n2yo.com/satellite/?s=23833 |title=N2YO.com|access-date=18 July 2015}}
References
{{Portal|Spaceflight}}
{{Reflist|2}}
{{GPS satellites}}
{{Orbital launches in 1996}}