Orbiting Vehicle 3-3 (also known as OV3-3), launched 4 August 1966, was the third satellite to be launched in the OV3 series of the United States Air Force's Orbiting Vehicle program. The satellite measured

charged particles In physics, a charged particle is a particle with an electric charge. It may be an ion, such as a molecule or atom with a surplus or deficit of electrons relative to protons. It can also be an electron or a proton, or another elementary pa ...

in orbit so that their danger to space-based payloads could be assessed. OV3-3 is still in orbit as of 29 July 2021.

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. Five distinct OV series of standardized satellites were developed under the auspices of these agencies. 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 Scout may refer to: Youth movement * Scout (Scouting), a child, usually 10–18 years of age, participating in the worldwide Scouting movement **Scouts (The Scout Association), section for 10-14 year olds in the United Kingdom ** Scouts BSA, sect ...

boosters. In this regard, the OV3 series was more akin to its civilian science program counterparts (e.g.

Explorer Exploration refers to the historical practice of discovering remote lands. It is studied by geographers and historians. Two major eras of exploration occurred in human history: one of convergence, and one of divergence. The first, covering most ...

). OV3 differed from NASA programs in its heavy use of off-the-shelf equipment, which resulted in lower unit cost. The first four satellites in the series were made the

Aerojet Aerojet was an American rocket and missile propulsion manufacturer based primarily in Rancho Cordova, California, with divisions in Redmond, Washington, Orange and Gainesville in Virginia, and Camden, Arkansas. Aerojet was owned by GenCorp ...

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 The Air Force Research Laboratory (AFRL) is a scientific research organization operated by the United States Air Force Materiel Command dedicated to leading the discovery, development, and integration of aerospace warfighting technologies, pl ...

(AFCRL), which also managed the entire series and provided four of the OV3 payloads.

Charles H. Reynolds, who worked at AFCRL from 1955, was the technical manager for the OV3 program. Prior to the launch of OV3-3, two other OV3 satellites had been placed into orbit. OV3-1, launched 22 April 1966, measured radiation around the Earth, returning data for over a year. Launched on 10 June 1966, OV3-4 was the second in the OV3 satellite series. It measured the effects of radiation on tissue-equivalent samples.

Spacecraft design

Like the rest of the OV3 satellites, OV3-3 was an octagonal prism, in length and width, with experiments mounted on booms. 2560 solar cells provided 30

Watt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James Wa ...

s of power. The satellite was spin-stabilized, but because it was asymmetrical once its booms were extended, OV3-3 maintained its attitude in orbit with a

precession Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In o ...

damper. The spacecraft was spin stabilized at 8 revolutions per minute (rpm) 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

. OV3-3 massed . Its design life-span was one year.

Experiments

OV3-3's scientific payload consisted of seven experiments originally flown on the failed

OV2-1 Orbiting Vehicle 2-1 (COSPAR ID: 1965–82C, also known as OV2-1), the first satellite of the second series of the United States Air Force's Orbiting Vehicle program, was an American life science research satellite. Its purpose was to determine ...

mission. Designed to measure particle radiation over a wide energy spectrum, the instruments included a Faraday Cup

electrometer An electrometer is an electrical instrument for measuring electric charge or electrical potential difference. There are many different types, ranging from historical handmade mechanical instruments to high-precision electronic devices. Modern e ...

, two directional telescopes, and three

spectrometers A spectrometer () is a scientific instrument used to separate and measure spectral components of a physical phenomenon. Spectrometer is a broad term often used to describe instruments that measure a continuous variable of a phenomenon where th ...

. OV3-3 also carried a magnetometer to measure magnetic fields and plasma fluctuations, aided in this by its VLF radio receiver.

Mission

Launched from

Vandenberg Space Launch Complex 5 Space Launch Complex 5 (SLC-5) was a launch pad at Vandenberg Space Force Base in California, United States. It was previously part of the Point Arguello Naval Air Station, during which time it was designated Launch Complex D or LC-D. Cons ...

on 4 August 1966 at 10:45:01 UTC via

Scout B The Scout family of rockets were American launch vehicles designed to place small satellites into orbit around the Earth. The Scout multistage rocket was the first orbital launch vehicle to be entirely composed of solid fuel stages. It was also t ...

rocket into a

polar orbit A polar orbit is one in which a satellite passes above or nearly above both poles of the body being orbited (usually a planet such as the Earth, but possibly another body such as the Moon or Sun) on each revolution. It has an inclination of abo ...

, OV3-3 was the third satellite to be launched in the OV3 series. The satellite measured trapped and precipitating particles and their correlated electromagnetic wave fields. Its systems performed well for 14 months until the onboard tape recorder failed in September 1967. Low-latitude, real-time tracking continued into 1969 when the spacecraft was deactivated. OV3-3 instruments returned data on solar protons, and data received from the satellite's VLF receiver determined the location of the

plasmapause The plasmasphere, or inner magnetosphere, is a region of the Earth's magnetosphere consisting of low-energy (cool) plasma. It is located above the ionosphere. The outer boundary of the plasmasphere is known as the plasmapause, which is defined ...

(the outer boundary of the Earth's inner magnetosphere).

Legacy and status

As of 29 July 2021, OV3-3 is still in orbit, and its position can be tracked on-line. The OV3 program ultimately comprised 6 missions, five of them successful. The last (OV3-6) flew on 4 December 1967. The OV3 program was terminated following OV3-6 in favor of the cheaper OV1 program.

References

{{Orbital launches in 1966 Spacecraft launched in 1966