OSCAR IV ( OSCAR 4) was the fourth

amateur radio satellite An amateur radio satellite is an artificial satellite built and used by amateur radio operators. It forms part of the Amateur-satellite service. These satellites use amateur radio frequency allocations to facilitate communication between amate ...

launched by Project

OSCAR Oscar, OSCAR, or The Oscar may refer to: People and fictional and mythical characters * Oscar (given name), including lists of people and fictional characters named Oscar, Óscar or Oskar * Oscar (footballer, born 1954), Brazilian footballer ...

and the first targeted for

Geostationary orbit A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular orbit, circular geosynchronous or ...

on 12 December 1965. The satellite was launched piggyback with three

United States Air Force The United States Air Force (USAF) is the Air force, air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its ori ...

satellites on a

Titan IIIC The Titan IIIC was an expendable launch system used by the United States Air Force from 1965 until 1982. It was the first Titan (rocket family), Titan booster to feature large solid rocket motors and was planned to be used as a launcher for the D ...

launch vehicle. Due to a booster failure, OSCAR 4 was placed in an unplanned and largely unusable

Geostationary transfer orbit In space mission design, a geostationary transfer orbit (GTO) or geosynchronous transfer orbit is a highly elliptical type of geocentric orbit, usually with a perigee as low as low Earth orbit (LEO) and an apogee as high as geostationary 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 Foothill College is a public community college in Los Altos Hills, California. It is part of the Foothill–De Anza Community College District. It was founded on January 15, 1957, and offers 84 Associate degree programs, 2 Bachelor's degree p ...

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, launched from Vandenberg AFB in California on 12 December 1961, which transmitted a “HI” greeting in Morse Code for three weeks, OSCAR 2, and OSCAR 3.

Spacecraft

OSCAR 4 massed and was a regular tetrahedron with edges 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. 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.

Mission

OSCAR 4, along with LES-3, LES-4, and OV2-3, was launched on the third Titan IIIC test flight on 22 December 1965 at 14:00:01 UT from Cape Canaveral LC41 just one second behind schedule. From an initial parking orbit of , 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. 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. The satellite remained in operation for 85 days, until 16 March 1966, and re-entered Earth's atmosphere on 12 April 1976.

Legacy

In 1969, AMSAT-NA was founded by radio amateurs working at NASA's

Goddard Space Flight Center The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory located approximately northeast of Washington, D.C., in Greenbelt, Maryland, United States. Established on May 1, 1959, as NASA's first space flight center, GSFC ...

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 Australis-OSCAR 5 (a.k.a. AO-5) is an amateur radio satellite that was launched into Low Earth Orbit on 23 January 1970 by a Thor Delta launcher from Vandenberg Air Force Base, Lompoc, California. AO-5 was launched piggyback with TIROS-M (I ...

, constructed by students at the

University of Melbourne The University of Melbourne (colloquially known as Melbourne University) is a public university, public research university located in Melbourne, Australia. Founded in 1853, it is Australia's second oldest university and the oldest in the state ...

References

{{DEFAULTSORT:OSCAR 4 Satellites orbiting Earth Amateur radio satellites Spacecraft launched in 1965