{{Short description|American navigation satellite used for GPS}} {{Use American English|date=December 2020}} {{use dmy dates|date=December 2020}} {{Infobox spaceflight | name = USA-80 | names_list = Navstar 2A-04<br/>GPS IIA-4<br/>GPS II-13<br/>GPS SVN-28 | image = | image_caption = | image_size = 290px

| mission_type = Navigation | operator = U.S. Air Force | COSPAR_ID = 1992-019A<ref name="Display"/> | SATCAT = 21930 | mission_duration = 7.5 years (planned)<br/>5.33 years (Achieved)

| spacecraft = GPS IIA | spacecraft_type = GPS Block IIA<ref name="GSP"/> | manufacturer = Rockwell International | launch_mass = {{cvt|840|kg}} | dimensions = {{cvt|5.3|m}} of long | power = 710 kg

| launch_date = 10 April 1992, 03:20:00 UTC | launch_rocket = Delta II 7925-9.5<br/>(Delta D208) | launch_site = Cape Canaveral, LC-17B | launch_contractor = McDonnell Douglas

| entered_service = 10 April 1992 | disposal_type = Graveyard orbit | deactivated = 15 August 1997

| orbit_reference = Geocentric orbit | orbit_regime = Medium Earth orbit<br/><small>(Semi-synchronous)</small> | orbit_slot = C2 (slot 2 plane C) | orbit_periapsis = {{cvt|19877|km}} | orbit_apoapsis = {{cvt|20390|km}} | orbit_inclination = 55.10° | orbit_period = 716.00 minutes | apsis = gee

| programme = Global Positioning System | previous_mission = USA-79 (GPS IIA-3) | next_mission = USA-83 (GPS IIA-5) }}

'''USA-80''', also known as '''GPS IIA-4''', '''GPS II-13''' and '''GPS SVN-28''', was an American navigation satellite which formed part of the Global Positioning System. It was the fourth 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&nbsp;km circular orbits inclined at 55.0°. These vehicles are placed in 6 orbit planes with four operational satellites in each plane.<ref name="Display">{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1992-019A|title=Display: Navstar 2A-04 1992-019A|publisher=NASA|date=14 May 2020|access-date=18 December 2020}} {{PD-notice}}</ref>

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&nbsp;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.<ref name="Display"/>

== Launch == USA-80 was launched at 03:20:00 UTC on 10 April 1992, atop a Delta II carrier rocket, flight number D208, flying in the 7925-9.5 configuration.<ref name="LL">{{cite web |url=http://planet4589.org/space/log/launchlog.txt|title=Launch Log|publisher=Jonathan's Space Report|first=Jonathan|last=McDowell|access-date=10 July 2012}}</ref> The launch took place from Launch Complex 17B (LC-17B) at the Cape Canaveral Air Force Station (CCAFS),<ref name="lvdb">{{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=10 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}}</ref> and placed USA-80 into a transfer orbit. The satellite raised itself into medium Earth orbit using a Star-37XFP apogee motor.<ref name="GSP">{{cite web |url=http://space.skyrocket.de/doc_sdat/navstar-2a.htm|title=GPS-2A (Navstar-2A)|first=Gunter|last=Krebs|work=Gunter's Space Page|access-date=10 July 2012}}</ref>

== Mission == On 12 May 1992, USA-80 was in an orbit with a perigee of {{cvt|19877|km}}, an apogee of {{cvt|20390|km}}, a period of 716.00 minutes, and 55.10° of inclination to the equator.<ref name="Trajectory">{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/displayTrajectory.action?id=1992-019A|title=Trajectory: Navstar 2A-04 1992-019A|publisher=NASA |date=14 May 2020|access-date=18 December 2020}} {{PD-notice}}</ref> It had PRN 28, and operated in slot 2 of plane C of the GPS constellation. The satellite had a mass of {{cvt|840|kg}}. It had a design life of 7.5 years;<ref name="GSP"/> however, it was retired early, on 15 August 1997. It was replaced by USA-117.

== References == {{Portal|Spaceflight}} {{Reflist|2}}

{{GPS satellites}} {{Orbital launches in 1992}}

Category:Spacecraft launched in 1992 Category:GPS satellites Category:USA satellites