While the history of spaceflight is filled with well-known spacecraft that have flown historic missions, it could be argued that there are a far greater number of obscure spacecraft that are largely unknown to the majority of even the most avid space enthusiasts. Among these are some genuine curiosities whose existence have largely been forgotten. Examples of these are surely the earliest flights of the OV satellite series which originally had an interesting means of reaching orbit.

The OV1 Series

The OV or “Orbital Vehicle” satellite series, which was first known by the name SATAR, was initiated by the Air Force Office of Aerospace Research back in the early 1960s as a means of orbiting scientific and technological experiments at minimal costs. To save money, this series of satellites was typically flown as secondary payloads on various USAF missions. The first series of satellites in this program, designated OV1, was specifically designed to ride piggyback on surplus Atlas ICBMs being flown to support other programs such as the USAF’s ABRES (Advanced Ballistic ReEntry System) flights. The ABRES program was started in 1963 with the goal of testing ICBM warhead technologies and assessing various penetration aids under realistic ballistic flight conditions. Typically these flights had excess payload capability available and they offered an inexpensive launch option for secondary payloads like OV1. The Atlas had already launched its first satellite back in 1958 as part of Project SCORE (see “Vintage Micro: The Talking Atlas”), was used to orbit America’s manned Mercury spacecraft and was already being used with a variety of upper stages to serve as a satellite launch vehicle so this versatile rocket was certainly suited to the task.

The OV1 satellites were built by the manufacturer of the Atlas ICBM, General Dynamics (whose space division was sold to Lockheed in 1993 and is now part of the aerospace giant, Lockheed Martin). Most of the OV1 satellites were of a standardized design consisting of a cylinder with hemispherical caps having a total length of 1.39 meters and a diameter of 0.69 meters. With a mass usually less than 100 kilograms and a volume of 0.17 cubic meters available in the cylindrical center section for about 36 kilograms experiment hardware, the OV1 was a microsatellite by today’s definition.

Since the Atlas rockets on which these satellites rode piggyback were flying suborbital trajectories to support their primary objectives, these satellites also included their own propulsion module designated OV1-PM to provide the final kick to get into orbit. The OV1-PM was 2.05 meters long with a maximum diameter of 0.72 meters and a mass of 354 kilograms. At the heart of the OV1-PM was a X-258 “Altair 2” solid rocket motor that generated 22.2 kilonewtons of thrust during a 28-second burn providing a delta-v of around 2,000 meters per second, depending on the OV1 satellite mass. This same rocket motor was also used as an upper stage on some early model Scout all-solid launch vehicles and the Delta D.

General Dynamics designed a standardized pod with a total mass of about 1,110 kilograms (including the satellite and its propulsion module) to carry the OV1/OV1-PM on the side of the Atlas during ascent. The OV1/OV1-PM would be deployed about five minutes after launch and then coast until it reached apogee when the X-258 motor would be ignited. Once in orbit, the OV1 satellite would separate from its spent propulsion module to start its mission.

The First OV1 Flights

The first satellite in this series ready for launch was OV1-1. With a mass of 85 kilograms, it carried seven experiments provided by Harvard University, the USAF Cambridge Research Laboratories and Aerospace Corporation. This suite of experiments was designed to measure proton concentrations, ion density, micrometeoroids, the Earth’s magnetic field as well as measure its infrared and ultraviolet emissions. The hemispherical endcaps of OV1-1 were covered with 2,500 solar cells to provide 22 watts of electrical power for the onboard systems. The satellite included a timer that would automatically shutdown the satellite after about 180 days in orbit.

The plan was for OV1-1 to be deployed from its side-mounted pod about five minutes after launch and coast to an altitude of 587 kilometers. At that point, the kick motor would be ignited placing the satellite into an approximately 560 by 2,400-kilometer retrograde orbit. OV1-1 lifted off on January 21, 1965 from Launch Complex 576B-3 at Vandenberg Air Force Base in California mounted on the side of Atlas 172D which was carrying the ABRES MTV-1 instrumented dummy warhead as its primary payload. While the Atlas performed as intended sending MTV-1 over the Pacific Ocean and towards its target near the Kwajalein Atoll, the door on the side pod carrying OV1-1 failed to open and deploy the secondary payload.

Undeterred by the failure, a second OV1 satellite was prepared for launch. OV1-3 (which was launched out of sequence) was a 92-kilogram satellite almost identical in appearance to OV1-1. The main difference between the satellites was the payload: OV1-3 carried experiments provided by the Air Force Weapons Laboratory meant to evaluate the biological hazards of trapped radiation. OV1-3 was launched in a side pod on Atlas 68D which lifted off from LC 576B-3 (which had recently been renamed ABRES B-3) on May 27, 1965 carrying a dummy Mk 3 warhead on a ABRES ballistic mission. Unfortunately, Atlas 68D blew up two minutes after launch destroying its primary and secondary payloads in the process.

A New Launch Method

This second unsuccessful OV1 flight would prove to be the last time these satellites would attempt to hitch a ride into space on an ICBM test flight. Although continuing to fly OV1 satellites as secondary payloads on ABRES flights was possible, the availability of an initial batch of a half dozen surplus Atlas D missiles earmarked specifically to support the OV1 program made it possible to launch Atlas missions dedicated to OV1 satellite launches. General Dynamics modified the OV1 pods so that a pair could be mounted side-by-side on the top of an Atlas in place of an experimental warhead. The option also existed to carry a third satellite in a side pod as before or other suborbital secondary payloads on these dedicated OV1 launches.

The next flight in the OV1 program would test this new box-shaped, dual-pod configuration on an Atlas D. For this test flight only one of the pair of pods actually carried a satellite. The 86-kilogram OV1-2 was equipped with a set of experiments from Aerospace Corp., the Air Force Space Systems Division, the Air Force Weapons Laboratory and Northrop designed to study X-rays, the Earth’s magnetic field as well as space radiation and its effects on living tissue.

OV1-2 was launched on October 5, 1965 from the ABRES B-3 launch complex using Atlas 34D which was also carrying a suborbital secondary payload in a side pod. On queue, OV1-2 and its propulsion module were deployed from their nose-mounted pod five minutes after launch and coasted to an altitude of 885 kilometers. At that point, the X-258 rocket motor ignited placing OV1-2 into a 417 by 3,477-kilometer retrograde orbit inclined 144° to the equator. With the first OV1 satellite finally in orbit, it proceeded to carry out its mission returning significant data on the effects of shielding on radiation dose rates.

The dual payload capability of General Dynamics’ new nose-mounted deployment system was finally utilized with the launch of OV1-4 and 5 on Atlas 71D. The 87.5-kilogram OV1-4 carried zero-g biological experiments and a thermal control experiment designed to test the properties of various materials and coatings. OV1-5, with a launch mass of 114 kilograms, carried instruments designed to provide data on Earth and space backgrounds at wavelengths ranging from 0.5 to 30 μm in support of the development of space-based surveillance systems. OV1-5 also carried a gravity gradient experiment as a test of future passive attitude control systems. Both satellites had a nominal mission length of 90 days.

The pair of satellites was launched along with a suborbital secondary payload on March 30, 1966 from ABRES B-3 at Vandenberg Air Fore Base. OV1-4 was successfully placed into an 885 by 1,013-kilometer orbit with an inclination of 144.5° while OV1-5 entered a 986 by 1,060-kilometer orbit with an inclination of 144.7°. This was the first time that a pair of satellites had been placed into orbit using a side-by-side configuration instead of being stacked one on top of the other (see “Vintage Micro: The First ELINT Satellites”).

The OV1 program would continue launching payloads into orbit primarily using surplus D and, later on, F-model Atlas missiles until 1971. During this time, OV1 was also joined by OV satellites from other series with a variety of designs built by other manufactures meant to support various space research projects sponsored by the USAF Aerospace Research Support Program. None of these satellites (or any other satellites, to the best of my knowledge) would ever attempt to reach orbit hitching a ride on a suborbital ICBM test flight as OV1-1 and 3 had done.

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Related Reading

“Vintage Micro: The Talking Atlas”, Drew Ex Machina, December 18, 2014 [Post]

“Vintage Micro: The First ELINT Satellites”, Drew Ex Machina, September 30, 2014 [Post]

“The First Titan III Launches”, Drew Ex Machina, September 1, 2014 [Post]

General References

Jos Heyman, “OV”, Directory of U.S. Military Rockets and Missile Appendix 3: Space Vehicles, Web site [Link]

Bernard C. Nalty, USAF Ballistic Missile Programs 1965 (Unclassified version), USAF Historical Division Liaison Office, March 1967

Chuck Walker with Joel Powell, Atlas: The Ultimate Weapon, Apogee Books, 2005

“Orbital Vehicle”, TRW Space Log, Vol. 5, No. 2, pp. 41-42, Summer 1965

“Aerospace Research Support Program”, TRW Space Log, Vol. 5, No. 4, p. 15, Winter 1965-66

“Twin Satellites Launched”, Flight International, p. 736, April 28, 1966

“Aerospace Research Support Program”, TRW Space Log, Vol. 6, No. 2, pp. 21-22, Summer 1966