|Mission type||Earth science|
|Launch mass||69 kg (152 lb)|
|Start of mission|
|Launch date||22 Apr 1966 09:45:00UTC|
|Launch site||Vandenberg PALC-D|
|Regime||Medium Earth Orbit|
|Perigee altitude||341.00 km (211.89 mi)|
|Apogee altitude||4,658.00 km (2,894.35 mi)|
|Period||138.70 minutes |
|Epoch||22 Apr 1966 09:50:00|
Orbiting Vehicle 3-1 (also known as OV3-1 and OPS 1527 ), launched 22 April 1966, was the first satellite in the OV3 series of the United States Air Force's Orbiting Vehicle program. The satellite measured radiation around the Earth, returning data for over a year. It is still in orbit as of 1 April 2021.
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.:417 Five distinct OV series of standardized satellites were developed under the auspices of these agencies.:425
Unlike the OV1 and OV2 series satellites, which were designed to use empty payload space on rocket test launches, the OV3 series was more akin to its civilian science program counterparts (e.g. Explorer). The six OV3 satellites all had dedicated Scout boosters and an integrated set of experiments. OV3 differed from NASA programs in its heavy use of off-the-shelf equipment, which resulted in lower unit cost.: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.:422–423
Like the rest of the OV3 satellites, OV3-1 was an octagonal prism, .74 m (2 ft 5 in) in length and width, with experiments mounted on booms. 2560 solar cells provided 30 Watts of power. Designed for a six month mission, its attitude in orbit was maintained by a precession damper.:422–423
OV3-1 carried six AFCRL experiments that had been flown on the unsuccessful 15 October 1965 OV2-1 mission,:423 designed to evaluate the long-term hazards of the Earth's Van Allen Belts to astronauts and satellites. They included two pairs of electrostatic analyzers, two plasma probes, two magnetometers, a Geiger counter, and a scintillation spectrometer. This "cosmic radiation" package could measure the angular distribution and energies of atomic particles as well as their interaction with local magnetic fields.:423
Launched from Vandenberg PALC-D on 22 April 1966 at 9:45:00 UTC via Scout B rocket, OV3-1 was the first in the OV3 satellite series. Though it was only designed to last for 6 months, OV3-1 continued operating past its one year anniversary, returning data for more than 3000 orbits. By that point, the experiments were normally only activated once a week since sufficient results had been obtained, although activation was made as frequently as possible during periods of high solar activity, range-scheduling capability permitting.
As of 1 April 2021, OV3-1 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.