{{Short description|US Air Force satellite}} {{Infobox spaceflight | name = OV3-2 | image = OV3-2.jpg | image_size = 180px | image_caption = OV3-2 | mission_type = Earth science | operator = USAF | COSPAR_ID = 1966-097A | SATCAT = S02517 | mission_duration =
| spacecraft_bus = | manufacturer = Space General | dry_mass = | launch_mass = {{convert|81|kg|lb|abbr=on}}<ref name="SP-133">{{cite book|author=William R. Corliss|author-link=William R. Corliss|title=Scientific Satellites|publisher=Science and Technical Information Division, Office of Technology Utilization, NASA|date=1967|location=Washington D.C.|pages=774|url=https://archive.org/details/scientificsatell00corl/page/774/mode/2up|access-date=1 April 2021}}</ref> | power =
| launch_date = {{start-date|28 October 1966 11:56:02}} UTC | launch_rocket = Scout B | launch_site = Vandenberg Space Launch Complex 5<ref name=log>{{Cite web|url=http://planet4589.org/space/log/launchlog.txt|title=Launch Log|last=McDowell|first=Jonathan|publisher=Jonathan's Space Report|access-date=27 September 2021}}</ref>
| last_contact = | decay_date = 29 September 1971
| orbit_epoch = 28 October 1966 12:00:00 | orbit_reference = | orbit_regime = Medium Earth Orbit | orbit_periapsis = {{convert|320.00|km|mi|abbr=on}} | orbit_apoapsis = {{convert|1597.00|km|mi|abbr=on}} | orbit_inclination = 82.000° | orbit_semimajor = | orbit_eccentricity = 0.08697 | orbit_period = 104.20 minutes <ref name=NSSDC>{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1966-097A|title=OV3-2|publisher=NASA|access-date=27 September 2021}}</ref> | orbit_RAAN = | orbit_arg_periapsis = | orbit_mean_anomaly = | orbit_mean_motion = | orbit_rev_number = | apsis = gee
| programme = ''OV3'' | previous_mission = OV3-3 | next_mission = OV3-5 }} '''Orbiting Vehicle 3-2''' (also known as '''OV3-2'''<ref name=NSSDC/>), launched 28 October 1966, was the fourth satellite to be launched in the OV3 series of the United States Air Force's Orbiting Vehicle program. The satellite measured charged particles in orbit, mapping irregularities in the ionosphere, particularly the auroral zone. OV3-2 reentered the Earth's atmosphere on 29 September 1971.
==History==
The Orbiting Vehicle satellite program arose from a US Air Force initiative, begun in the early 1960s, to reduce the expense of space research. Through this initiative, satellites would be standardized to improve reliability and cost-efficiency, and where possible, they would fly on test vehicles or be piggybacked with other satellites. In 1961, the Air Force Office of Aerospace Research (OAR) created the Aerospace Research Support Program (ARSP) to request satellite research proposals and choose mission experiments. The USAF Space and Missiles Organization created their own analog of the ARSP called the Space Experiments Support Program (SESP), which sponsored a greater proportion of technological experiments than the ARSP.<ref name="Brit">{{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}}</ref>{{rp|417}} Five distinct OV series of standardized satellites were developed under the auspices of these agencies.<ref name="Brit"/>{{rp|425}}
Unlike the previously initiated OV1 and OV2 series of satellites, which were designed to use empty payload space on rocket test launches, the six OV3 satellites all had dedicated Scout boosters. In this regard, the OV3 series was more akin to its civilian science program counterparts (e.g. Explorer). OV3 differed from NASA programs in its heavy use of off-the-shelf equipment, which resulted in lower unit cost.<ref name="Brit"/>{{rp|422–423}}
The first four satellites in the series were made the Aerojet subsidiary Space General Corporation under a $1.35m contract awarded 2 December 1964, the first satellite due October 1965. The last two satellites were built by Air Force Cambridge Research Laboratory (AFCRL), which also managed the entire series and provided four of the OV3 payloads.<ref name="Brit"/>{{rp|422–423}}
thumb|left|Charles H. Reynolds, Technical Manager of OV3|alt=Charles H. Reynolds, Technical Manager of OV3
Charles H. Reynolds, who worked at AFCRL from 1955, was the technical manager for the OV3 program.<ref name=reviewjuly1967>{{cite magazine|url=https://play.google.com/books/reader?id=aQtIAQAAIAAJ&hl=en&pg=GBS.RA6-PA10|title=Anniversary of OV3-1|author=Charles H. Reynolds|magazine=research review|publisher=Office of Aerospace Research|volume=6|number=7|pages=10–11|date=July 1967|access-date=1 April 2021}}</ref>
Prior to the launch of OV3-2, three other OV3 satellites had been placed into orbit, all radiation measuring spacecraft launched in 1966.<ref name="Brit"/>{{rp|423}}<ref name=log/>
==Spacecraft design==
Like the rest of the OV3 satellites, OV3-2 was an octagonal prism, {{cvt|.74|m}} in length and width, with experiments mounted on booms. 2560 solar cells provided 30 Watts of power. The satellite was spin-stabilized, but because it was asymmetrical once its booms were extended,<ref name=auroral>{{cite book|title=Low-Energy Auroral Electrons Measured by Satellite OV3-1|url=https://books.googleusercontent.com/bookscontent?req=AKW5Qadlmcty2L2tgax2N5z5McqgP0u6hs7jtTRYuV_Mlj_j2G0UZxw7KUAjly5OMjXFeK9-H82Q_djDtMEpyHbTlU6QZNb0oVHknbCD9pSKtk8QKUwRWzQMvH8LcqZPzWtb4Dn0n3D806pbVHu95hXqF6vjCCfDhxV05_BxJf5PHns6tBq1FGmc9Ya3HvCWGmrxIBsH-rj3tqrUiOiynUdgn1Fhp5jxVqSf75msQ5LS-Mp3ZH7itzg--ukr62kiCB9nFlHJSeI3GIvWqi2N0f8p8qTUKYaw|author=George A. Kuck|date=August 1968|access-date=8 June 2021}}</ref> OV3-2 maintained its attitude in orbit with a precession damper.<ref name="Brit"/>{{rp|422–423}} The spacecraft was spin stabilized at eight revolutions per minute (rpm)<ref name=NSSDC/> A Sun sensor, as well as an onboard tri-axial magnetnometer, gave information on the satellite's aspect (facing), its spin rate, and rate of precession.<ref name=review>{{cite magazine|magazine=Research Review|url=https://books.google.com/books?id=Gz8qAQAAIAAJ&dq=%22research+review%22+%22ov3-2%22&pg=RA1-PA4|pages=4–5|publisher=Office of Aerospace Research|volume=6|number=2|date=February 1967|title=AFCRL covers November 1966 Eclipse }}</ref><ref name="Brit"/>{{rp|423}}
OV3-2 massed {{convert|81|kg|lb|abbr=on}}<ref name="SP-133"/> Its design life-span was one year.<ref name="Brit"/>{{rp|423}}
==Experiments==
OV3-2 carried five AFCRL experiments designed primarily to investigate low-energy particles in the Van Allen Belts,<ref name="Brit"/>{{rp|423}} looking for irregularities in the ionosphere, particularly in the auroral zone.<ref name=report>{{cite book|title=Report on Research at AFCRL July 1965-June 1967|page=113|date=November 1967|publisher=The Air Force Cambridge Research Laboratories|location=Bedford, Massachusetts|oclc=316861363}}</ref> In addition to its magnetometer, the spacecraft carried two retarding-potential analyzers (RPA) orthogonally mounted on one {{cvt|54|inch|cm}} boom<ref name=review/> and a mass spectrometer, both to detect heavy ions;<ref name="Brit"/>{{rp|423}} a pair<ref name=NSSDC/> of electrostatic analyzers to measure electrons in the 15-80 keV range;<ref name=sig67>{{cite book|url=https://books.google.com/books?id=eDoXF1GgdDgC&dq=ov3-2&pg=RA1-PA168|title=Significant Achievements in Space Science 1967|oclc=14475382|publisher=NASA|location=Washington|date=1968}}</ref> and two Langmuir probes on separate {{cvt|54|inch|cm}} booms to measure electron density in the 0-2 keV range.<ref name=review/><ref name="Brit"/>{{rp|423}} The satellite also carried two standing-wave impedance probes on {{cvt|30|ft}} extendable dipoles generating at 2 and 7 Mhz.<ref name=review/>
Joseph H. Geary was the payload manager for OV3-2.<ref name=review/>
==Mission==
thumb|alt=Artist's rendition of the OV3-2 satellite in orbit|Artist's rendition of the OV3-2 satellite in orbit.
Launched from Vandenberg Space Launch Complex 5 on 28 October 1966 at 11:56:02 UTC via Scout B rocket into a polar orbit,<ref name=NSSDC/> OV3-2 was the fourth satellite to be launched in the OV3 series.<ref name=log/> While OV3-2 conducted ionospheric and aurora research in orbit in conjunction with AFCRL KC-135 aircraft flying underneath.<ref name=report/> The National Research Council of Canada also conducted coordinated, simultaneous ionospheric observations.<ref name=report2>{{cite book|title=AFCRL Space Science Research During 1967 (Annual Report to COSPAR)|editor=A. McIntyre|publisher=Office of Aerospace Research. United States Air Force|location=Bedford, Massachusetts|date=January 1968|oclc=69188216}}</ref> OV3-2's launch was timed such that it could observe ambient charged particle variations before, during, and after the 12 November 1966 South American solar eclipse.<ref name=NSSDC/>
As a result of the erratic performance of the command system, tape recorded data was not obtained until orbit 58 (four days after launch).<ref name=NSSDC/> In 1967, the tape recorder failed, and an additional command system at Churchill, Manitoba was set up to obtain real-time data.<ref name=report2/> This data had to be manually reduced for interpretation because of a malfunction of OV3-2's onboard clock. Some RPA data was lost due to the failure of the thermal equalization probe.<ref name=NSSDC/> The satellite operated throughout 1967,<ref name=sig67/> returning high quality data.<ref name=report/>
The satellite was tracked from the ground from January 1967 to March 1969, a period of rising solar activity, to determine atmospheric densities at heights of {{cvt|275|km}} and {{cvt|320|km}}. The deduced values were compared to those returned by Explorer 32, also in orbit at the time. Good data were obtained.<ref name=NSSDC/>
OV3-2 reentered the Earth's atmosphere on 29 September 1971.<ref name=cat>{{Cite web|url=https://www.planet4589.org/space/log/satcat.txt|title=Satellite Catalog|last=McDowell|first=Jonathan|publisher=Jonathon's Space Report|access-date=27 September 2021}}</ref>
==Legacy==
The OV3 program ultimately comprised 6 missions, five of them successful. The last (OV3-6) flew on 4 December 1967.<ref name=log/> The OV3 program was terminated following OV3-6 in favor of the cheaper OV1 program.<ref name="Brit"/>{{rp|423}}
==References== {{Reflist}}
{{Orbital launches in 1966}}
Category:Spacecraft launched in 1966