Orbiting Vehicle
Typically, OV satellites carried scientific and/or technological experiments, 184 being successfully orbited through the lifespan of the program.
The first OV series, designated OV1, was built by General Dynamics and carried on suborbital Atlas missile tests; the satellites subsequently placed themselves into orbit by means of an Altair-2 kick motor.
The Orbiting Vehicle satellite program arose from a US Air Force initiative, begun in the early 1960s, to reduce the expense of space research.
General Dynamics received a $2 million contract on 13 September 1963 to build a new version of the SPP (called the Atlas Retained Structure (ARS)) that would carry a self-orbiting satellite.
However, in 1964, the Air Force transferred ABRES launches to the Western Test Range causing a year's delay for the program.
[3] Ultimately, only the first of the SATARs, (OV1-1, called Atmospheric Research Vehicle (ARV) at the time)[4]: 24 ever flew piggyback on an ABRES mission.
The rest were flown on ex-ICBM Atlas D and F boosters specifically purchased by the OAR for the OV1 series (except OV1-6, which flew on the Manned Orbiting Laboratory test flight on 2 November 1966).
[6] In late May 1967, during a period of high solar and magnetic activity, OV1-9 returned the first evidence of Earth's long theorized but never measured electric field.
These data enabled scientists to determine the relative density of neon to magnesium in the solar corona through direct observation rather than using complicated mathematical models.
[10] Data returned by OV1s 15 and 16 returned the first substantial set of data on the density of Earth's atmosphere between the altitudes of 100 km (62 mi) and 200 km (120 mi) and proved that increased solar activity increased the air density at high altitudes, contradicting the prevailing model of the time.
[12] OV1-15/16 data led to improved atmospheric models that allowed the Air Force to better predict where and when satellites would decay and reenter.
Upon the cancellation of ARENTS due to delays in the Centaur rocket stage, the program's hardware (developed by General Dynamics) was repurposed to fly on the Titan III[1]: 417 : 422 (initially the A,[20] ultimately the C) booster test launches.
Four small solid rocket motors spun, one on each paddle, were designed to spin the OV2 satellites upon reaching orbit, providing gyroscopic stability.
Measuring the angle at which protons encountered the satellite also helped refine theoretical models of how the magnetosphere interacts with the flux of charged particles.
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.
[1]: 423 [18] The OV4 series was designed to utilize space aboard the Manned Orbiting Laboratory (MOL) test flights.
These two satellites would investigate long range radio propagation in the charged atmosphere of the ionosphere analogous to the whispering gallery transmission of sounds under a physical dome.
[1]: 423 In this way, the OV4-1 pair would evaluate the ionosphere's F layer as method of facilitating HF and VHF transmissions between satellites not in line of sight of each other.
[14] [18] The OV5 program was a continuation of the Environmental Research Satellite (ERS) series developed by Space Technology Laboratories, a subdivision of TRW Inc.
These were very small satellites launched pick-a-back with primary payloads since 1962—a natural fit under the Orbiting Vehicle umbrella.
The Space Test Program followed the new trend in satellites, which preferred custom-built one-offs with specific payloads to vehicles built on standardized plans.
