Orbiting Vehicle

Program origin and operations

The Orbiting Vehicle program grew from a US Air Force initiative in the early 1960s to reduce space research costs by standardizing satellites and flying them on test vehicles or as piggyback payloads. In 1961, the Air Force Office of Aerospace Research (OAR) established the Aerospace Research Support Program (ARSP) to solicit and select satellite experiments. A parallel organization, the Space Experiments Support Program (SESP) under the USAF Space and Missiles Organization, sponsored a larger share of technological experiments.

The OAR annual budget in 1966 was notably low, partly because secondary launches on rocket test flights were inexpensive; however, these launches had lower reliability, and of five OV missions in 1965 only one succeeded. Each rocket flew to a unique orbit, so a launch failure meant the loss of data specific to that trajectory, and experiments often had no backup. Experiments were proposed by various laboratories, ranging from small black boxes to complete satellites, and were prioritized by OAR based on scientific merit, feasibility, funding, and managerial oversight.

Final selections were approved by Air Force Headquarters and the Department of Defense, with NASA consulted to avoid duplication. OAR chose 22 experiments for satellite flights in 1966 and 30 for 1967. Implementation and rocket procurement were handled by the Los Angeles OAR office, commanded by Lt. Col. John C. Hill, located at Air Force Space Systems Division (SSD) Headquarters in Los Angeles; integration of rocket and satellite was managed by SSD and the Air Force Ballistic Systems Division.

OV1

The OV1 series evolved from 2.7 m Scientific Passenger Pods (SPP) attached to suborbital Atlas missile tests beginning 2 October 1961. On 13 September 1963, General Dynamics received a $2 million contract to build an Atlas Retained Structure (ARS) carrying a self-orbiting satellite. The original SATAR satellites were to launch from the Eastern Test Range on Atlas missions testing Advanced Ballistic Re-Entry System (ABRES) nosecones, but in 1964 ABRES launches moved to the Western Test Range, causing a year delay and requiring mass reduction due to polar orbit constraints.

After OV1-1, the last ABRES test launch, OV1-2 through 12 flew on decommissioned Atlas D ICBMs except OV1-6, which launched on a Titan IIIC for the Manned Orbiting Laboratory test flight. OV1-13 onward used decommissioned Atlas Fs. The standard OV1 satellite measured 1.387 m long and 0.69 m in diameter, with a cylindrical experiment housing capped by flattened cones, 5000 solar cells producing 22 watts, two 0.46 m antennae, and 12 helium-pressurized hydrogen peroxide thrusters for attitude control.

Starting with OV1-7, solar cells were flat and the Vertistat attitude system using a Sun sensor was added. OV1-13 and OV1-14 introduced pulse-code modulation digital telemetry for more precise data return.

OV2

The OV2 series originated from the Advanced Research Environmental Test Satellite (ARENTS) program, intended to support Vela satellite monitoring of the Partial Test Ban Treaty. After ARENTS was canceled due to Centaur rocket delays, its General Dynamics hardware was repurposed for Titan III booster test launches. Northrop produced the satellites under program manager William C. Armstrong. Each OV2 was a roughly cubical aluminum honeycomb structure 0.61 m high and 0.58 m wide, with four 2.3 m paddle-like solar panels at the upper corners, each with 20,160 solar cells, providing 63 W of power including NiCd batteries.

Experiments mounted outside the cube; satellite systems inside included a tape recorder, command receiver, and PAM/FM/FM telemetry. Four small solid rocket motors, one on each paddle, spun the satellite for gyroscopic stability, maintained by cold-gas jets using a solar aspect sensor and two fluxgate magnetometers; a damper prevented precession. Passive thermal control prevented overheating. Five OV2 satellites were planned with different objectives; only OV2-5, a radiation and astronomical satellite, achieved significant success.

OV2-5 proton energy data from 2–13 October 1968 in the 0.060 to 3.3 MeV range showed an eight-fold reduction in particle flux between solar storms and quiet periods, and angle measurements refined magnetosphere models.

OV3

The six OV3 satellites were the only series with dedicated Scout boosters, making them more akin to NASA's Explorer program, though they used off-the-shelf equipment for lower cost. Charles H. Reynolds of AFCRL was technical manager. The OV3 satellites were octagonal prisms 0.74 m in length and width (0.53 m for OV3-5 and OV3-6), with experiments on booms, 2560 solar cells providing 30 W, and spin stabilization at 8 rpm. OV3-2 used a precession damper due to asymmetry after boom extension.

A sun sensor and tri-axial magnetometer provided aspect, spin rate, and precession data. Design life was one year. Five of six missions succeeded; the last, OV3-6, flew on 4 December 1967, after which the program was terminated in favor of the cheaper OV1 series. OV3-1 returned data on electron energy and distribution in auroral regions.

OV3-4 data helped refine radiation dosage models for astronauts. OV3-3 VLF receiver data determined the plasmapause location. OV3-2 observed charged particle variations during the 12 November 1966 South American solar eclipse and conducted coordinated ionospheric and aurora research with AFCRL KC-135 aircraft and the National Research Council of Canada.

Did You Know?

• OV1-4's Tissue Equivalent Ionization Chamber, calibrated against Gemini 4, determined that astronauts at ~950 km altitude would receive 4 rads per day at 30° inclination or 1.5 rads per day at polar inclination.
• The last OV satellite, an OV1, flew in 1971 under the auspices of the Space Test Program, which succeeded the OV program.