OSCAR 4
{{Short description|Amateur radio satellite}}
{{Infobox spaceflight
| name = OSCAR 4
| image = OSCAR 4 interior AMSAT.jpg
| image_caption = OSCAR 4 with exterior panels removed
| mission_type = Communications
| operator = Project OSCAR{{\}}DoD
| website =
| COSPAR_ID = 1965-108C
| SATCAT = 01902
| mission_duration =
| spacecraft_bus =
| manufacturer =
| dry_mass =
| launch_mass = {{Convert|18.1|kg|lb}}
| power =
| launch_date = {{start-date|21 December 1965}}
| launch_rocket = Titan IIIC 3C-8
| launch_site = Cape Canaveral LC-41
| launch_contractor =
| last_contact =
| decay_date = {{end date|1976|04|12|df=y}}
| orbit_epoch = 20 December 1965
| orbit_reference = Geocentric
| orbit_regime = Geostationary (planned); Geostationary transfer orbit (actual)
| orbit_periapsis = {{convert|162|km|sp=us}}
| orbit_apoapsis = {{convert|33561|km|sp=us}}
| orbit_eccentricity = 0.71843
| orbit_inclination = 26.80 degrees
| orbit_period = 587.4 minutes
| apsis = gee
| programme = OSCAR
| previous_mission = OSCAR 3
| next_mission = OSCAR 5
}}
OSCAR IV ({{aka}} OSCAR 4) was the fourth amateur radio satellite launched by Project OSCAR and the first targeted for Geostationary orbit on 12 December 1965. The satellite was launched piggyback with three United States Air Force satellites on a Titan IIIC launch vehicle. Due to a booster failure, OSCAR 4 was placed in an unplanned and largely unusable Geostationary transfer orbit.
Project OSCAR
Project OSCAR Inc. was started in 1960 by members of the TRW Radio Club of Redondo Beach, California as well as persons associated with Foothill College to investigate the possibility of putting an amateur satellite in orbit. Project OSCAR was responsible for the construction of the first Amateur Radio Satellites: OSCAR 1,{{cite book|title=Nanosatellites: Space and Ground Technologies, Operations and Economics|page=496|publisher=John Wiley & Sons, Ltd.|date=2020|location=Glasgow |editor=Rogerio Atem de Carvalho |editor2=Jaime Estela |editor3=Martin Langer|isbn=978-1-119-04203-7|oclc=1126347525}} launched from Vandenberg AFB in California on 12 December 1961, which transmitted a “HI” greeting in Morse Code for three weeks,{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1961-034B|title=OSCAR 1|publisher=NASA Space Science Data Coordinated Archive|access-date=26 November 2020}} OSCAR 2, and OSCAR 3.
Spacecraft
OSCAR 4 massed {{convert|15|kg}} and was a regular tetrahedron with edges {{convert|48|cm}} long. It had four independent monopole antennae and contained a tracking beacon transmitter and a communications repeater. It was powered by a solar cell array and batteries.{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1965-108C|title=OSCAR 4|publisher=NASA Space Science Data Coordinated Archive|access-date=26 November 2020}} The satellite marked the first attempt for a High Earth Orbit (HEO) or GeoStationary Earth Orbit (GEO) amateur radio satellite, later categorized by AMSAT as Phase 3 and Phase 4. Improvements from prior OSCAR satellites included a higher power (3 Watt) 10 kHz wide linear transponder (144 MHz uplink and 432 MHz downlink), due to the higher planned orbit.{{cite web |url=http://www.amsat.org/amsat-new/AboutAmsat/amsat_history.php |title=Space Satellites from the World's Garage -- The Story of AMSAT |last1=Baker |first1=Keith |last2=Jansson |first2=Dick |date=23 May 1994 |access-date=15 February 2013 |url-status=dead |archive-url=https://web.archive.org/web/20061005160332/http://www.amsat.org/amsat-new/AboutAmsat/amsat_history.php |archive-date=5 October 2006 }}
Mission
File:Titan3C launch 22 Dec 1965.jpg
OSCAR 4, along with LES-3, LES-4, and OV2-3, was launched on the third Titan IIIC test flight{{cite web|date=27 December 1965|title=Titan 3 Transtage Malfunctions, Fails to Achieve Circular Orbit|url=http://archive.aviationweek.com/issue/19651227#!&pid=27|magazine=Aviation Week and Space Technology|location=New York|publisher=McGraw Hill Publishing Company|page=27|access-date=24 November 2020|url-access=subscription}} on 22 December 1965 at 14:00:01 UT from Cape Canaveral LC41{{Cite web|url=http://planet4589.org/space/log/launchlog.txt|title=Launch Log|last=McDowell|first=Jonathan|publisher=Jonathan's Space Report|access-date=November 26, 2020}} just one second behind schedule. From an initial parking orbit of {{convert|194|km}}, the Titan's Transtage boosted into a transfer orbit pending a final burn to circularize its orbit. However, this final burn, scheduled for T+6:03:04 after liftoff, never occurred due to a leaking valve in the booster's attitude control system.{{rp|422}} OSCAR 4, LES-3 and LES-4, were released from the Transtage, albeit much later than intended, likely by the booster's backup timer; OV2-3 remained attached and did not operate.{{cite magazine| date = 1987| title = The Orbiting Vehicle Series of Satellites| magazine = Journal of the British Interplanetary Society| location = London| publisher = British Interplanetary Society |last1=Powell|first1=Joel W.|last2=Richards|first2=G.R.|volume=40|page=422}}
The satellite remained in operation for 85 days, until 16 March 1966, and re-entered Earth's atmosphere on 12 April 1976.{{cite web |url=http://space.skyrocket.de/doc_sdat/oscar-4.htm |title=OSCAR 4|publisher=Gunter's Space Page |date=31 December 1999 |access-date=26 November 2020 }}
Legacy
In 1969, AMSAT-NA was founded by radio amateurs working at NASA's Goddard Space Flight Center and the Baltimore-Washington DC region, to continue the efforts begun by Project OSCAR. Its first project was to coordinate the launch of Australis-OSCAR 5, constructed by students at the University of Melbourne.
References
{{Reflist}}
{{Include-NASA}}
{{Portal|Spaceflight}}
{{Orbital launches in 1965}}
{{OSCAR satellites}}
{{DEFAULTSORT:OSCAR 4}}
Category:Satellites orbiting Earth