Orbiting Vehicle (OV)
The Orbiting Vehicle (OV) series of satellites were launched by the US Air Force for a diverse range of objectives. The series can be further sub-divided into the OV1, OV2, OV3, OV4 and OV5 satellites.
|Failed to orbit
|Failed to orbit
|Thermal control experiments
|Optical radiation test
|Failed to orbit
|Failed to orbit
|Cosmic ray telescope
|Radiation studies; also known as Flare Activated Radio-biological Observatory (Faro)
|Air density, solar studies; also known as Solar Perturbation of Atmospheric Density Experiments Satellite (Spades)
|Ionospheric drag experiment; also known as Cannonball-1
|Ionospheric studies; also known as Orbis Cal-2
|Radar calibration, radiation studies
|Radar calibration, air density studies
Launch dates of the OV1 sub-series
The Orbiting Vehicle (OV)1 series was built by Convair (General Dynamics) as a multi purpose spacecraft. The basic satellite was a cylinder of 1.40 m long and 0.69 m in diameter with a small globe on one or both ends. It included a jettisonable propulsion module with an Altair 2 (X258) solid fuelled motor. Normally the satellite was mounted in the nose cone but in the case of OV1-1, OV1-3 and OV1-86 the structure was side mounted.
|Photo: Author's collection
The purpose of OV1-1, which was carried in a side-pod on a test flight of the Atlas Advanced Ballistic Re-entry System (Abres), was to study trapped radiation. The 85 kg satellite carried an omni-directional proton spectrometer, a micrometeorite detector, an infrared/ultraviolet radiometer, an aspect magnetometer, a solar aspect sensor, a radio noise radiometer and an ion density impedance probe. The satellite was intended to be placed in a 560 x 2400 km orbit but the separation mechanism failed to release the satellite from the launch vehicle.
OV1-2, which had a mass of 88 kg, conducted radiation studies to measure the impact of radiation on humans. It also tested the back-to-back launch configuration of the OV1 series but with a single satellite mounted. The payload consisted of proton and electron dosimeters and spectrometers, an X-ray detector, a magnetometer, two tissue equivalent ion chambers and a shielded proton/electron dosimeter.
The 92 kg OV1-3 payload, which was carried in a side pod, was to evaluate the biological hazards of trapped radiation and carried a tissue equivalent plexiglass human torso which was implanted with an ion chamber, spectrometer and linear energy transfer device. The launch vehicle exploded after 2 minutes of flight.
The OV1-4 satellite conducted thermal control experiments with wafers of various materials and coatings. It also performed zero-gravity experiments on chlorella algea and multi-cell duck weed and exposed these specimens to alternate 12 hour periods of light and darkness as photo cells measured the cell division of the organisms. The mass of the satellite was 87.5 kg.
The OV1-5 satellite which had a mass of 114 kg, measured the optical background of the Earth as well as the background of space to provide a basis for military surveillance techniques. Called the Background Optical Radiation experiment, it utilised five optical sensors of which three pointed to the Earth and two away from the Earth. The sensors operated in the ultraviolet, infrared and visible bands of the spectrum. In addition the satellite tested the varistat gravity gradient stabilisation system.
The 202 kg OV1-6 satellite carried several balloons which were ejected and served as optical targets which were subject to radiometer measurements and ground observations.
The OV1-7 was to investigate the night airglow, the molecular oxygen distribution, solar X-rays, cosmic rays, charged particles and electric fields of the upper atmosphere. The instruments carried were a solar X-ray monitor, a nightglow photometer, an electric field detector, a charged particle detector and several radio beacons. The 117 kg satellite failed to orbit as the door of the payload bay of the launch vehicle, which was the same as for OV1-8, did not open quickly enough.
The OV1-8 had a mass of 3.2 kg and, when deployed, consisted of a 9.14 m diameter wire mesh sphere with a balloon inside. The satellite was used for passive communications tests and to demonstrate the feasibility of the erection of an open gird structure in space. Also referred to as PasComSat, the balloon decomposed, as planned, after a few orbits due to the intense solar ultraviolet radiation.
|Photo: Author's collection
A number of radiation experiments were carried on 104 kg OV1-9, including an electrostatic analyser for the study of electrons and protons, a magnetic analyser and scintillation spectrometer for electrons, two solid state spectrometers and range energy spectrometer for the measurement of protons, a low-frequency antenna and amplifier to study exospheric radiation and three tissue-equivalent ion chambers to determine the space radiation hazard to man.
OV1-10, with a mass of 130 kg, conducted further studies of space radiation with an all-sky Lyman-alpha photometer to measure hydrogen radiation, a scanning monochromator for ultraviolet day-glow photometry, a monochromator and Geiger-Müller counters for day-glow photometry, a crystal spectrometer to measure solar X-rays, a heavy primary cosmic ray telescope and a dual rubidium vapor magnetometer.
The OV1-86 consisted of a satellite similar to the OV1-8 mated with a propulsion module as used on OV1-6. The objective of the flight was to measure the change over time, in energy of cosmic rays as well as the isotrophy of those rays. It was also to determine the emission properties of the Earth's oxygen mantle and to determine the radiometric temperature of the Earth's atmosphere. The instruments carried consisted of a cosmic ray telescope, a 60GC radiometer, a 1-14B interferometer and a WW-4 radiometer. Because the 105 kg satellite tumbled only partial data was gathered.
The 153 kg OV1-11 was equipped with eight experiments to measure solar emissions, altitude distribution of atmospheric oxygen and ozone and charged particles. The instruments included a solar X-ray spectrometer and monitor, a plasma wave detector, a night-glow probe, an ultraviolet radiance spectrometer and instruments to measure electron and proton flux. The satellite failed to separate from the launch vehicle. OV1-11 was carried on the same launch vehicle as OV1-86 but the failure of the apogee motor prevented the satellite to separate from the launch vehicle.
The 140 kg OV1-12 satellite made biophysical and physical measurements of the space environment during solar flare activity as part of an overall programme to assess the effect of space radiation on humans. The experiments, which were collectively known as WL701 Flare Activated Radio biological Observatory (FARO), were:
- a Tissue Equilibrium Ion Chamber
- a Linear Energy Transfer Spectrometer
- a 20 to 40 MeV Proton Detector
- a 45 to 110 MeV Proton Detector
- a 3.5 to 5.0 MeV Electron Spectrometer
- a Solar Flare Detector
- a X-Ray Scintillator
- a Solid State Radiation Monitor
- a High Energy Particle Detector
- a Dose Spectrometer
- an Omnidirectional Proton/Electron Spectrometer
The 107 kg OV1-13 carried four spectrometers, a Geiger-Müller counter, a magnetic field analyser and an electrostatic analyser to measure radiation below an altitude of 8000 km. In addition the satellite evaluated the effect of the space environment on bearings, the friction between various material combinations and the performance of flexible cadmium-sulphide solar cells.
The power system of the 100 kg OV1-14 satellite failed after one week. It carried eight instruments to measure solar Lyman-alpha radiation including particle detectors measuring proton fluxes, proton spectra, electron spectra and time dependence of particles, as well as a dE/dx telescope.
OV1-15 was launched to identify the cause of large and sudden fluctuations encountered in satellite trajectories with the ultimate goal of being able to predict these fluctuations and their magnitude. The satellite investigated the upper atmosphere with an array of instruments which included a microphone density gauge, ion gauges, mass spectrometers, energetic particle detectors, solar X-ray and ultraviolet flux monitors, an ionosphere monitor and a tri-axial accelerometer. In addition ground based measurements were made. The 213 kg satellite was also known as Solar Perturbation of Atmospheric Density Experiment (Spades).
OV1-16 measured the time and space variations of the atmospheric density. Also referred to as Cannonball-1 or Low Altitude Density Satellite (Loads)-1, the satellite was a brass sphere with a diameter of 58 cm and a mass of 272 kg giving it a density equal to 690.5 kg/cubic meter, required to ensure that the satellite would not have decayed immediately. It carried a tri-axial accelerometer.
OV1-17 measured incoming solar electromagnetic radiation and the reaction of this radiation with the Earth's outer atmosphere. The twelve experiments included:
- a horizon dayglow sensor
- a horizon nightglow sensor
- solar X ray detectors
- an instrument for particle measurements
- an instrument for electric field measurements
- an extremely low frequency radiowave propagation instrument
- thermal control coatings
- a meteor trail calibration beacon
- fourteen cadmium sulphide solar cells for evaluation
The satellite, which had a mass of 142 kg, was not correctly stabilised and spinned, resulting in four experiments, which required proper stabilisation, returning useless data. The combined payloads on this flight have also been referred to as P69-1.
Orbis Cal-2, or OV1-17A, studied the unusual transmission of radiowaves through the ionosphere by monitoring the satellite with several ground stations. The 221 kg satellite consisted of the propulsion module of OV1-17 which was fitted with two radio beacons operating at 8.98 and 13.25 MHz.
OV1-18 studied the characteristics of the ionosphere as they affect radio wave propagation. The sixteen experiments gathered information on horizontal ion density gradients, electric fields and gamma rays. As the satellite did not stabilise properly in orbit, some of the data could not be used.
OV1-19 investigated the events which cause and sustain trapped radiation in the Van Allen belts for which it carried seven experiments. Another five experiments were carried to study the hazards of incoming and trapped radiation to man.
OV1-20 and OV1-21 carried experiments to investigate the properties of the near-Earth environment. The first satellite ejected a further satellite known as OAR-901, Low Altitude Density Satellite II or Cannonball-2. This was a brass sphere which made air density measurements in the fringes of the Earth's atmosphere. OV1-20 itself carried an energetic proton analyser to measure the spatial energy dependency of trapped proton flux, as well as a particle and flux thermal detector to measure the electron density and temperature in the upper atmosphere. OV1-21 was equipped with an experiment to determine the non-linear impedance and non-linear plasma effects of a long electric dipole antenna, an experiment to measure the atomic oxygen density and the variations in this density during geomagnetic activity as well as an instrument to measure the solar flux and atmospheric composition. Furthermore the satellite released six sub-satellites:
- the Radar Tracking Density Satellite, OAR-907 or Musketball, which carried a C-band transponder to make air density measurements in the fringes of the Earth's atmosphere
- a 112 cm diameter rigid sphere (AVL-802 or Rigid Sphere-2)
- three inflatable spheres with a diameter of 213 cm (identified as Grid Sphere-1 and -2 and Mylar Balloon) which were used to determine the ballistic coefficient of spheres and measure the change in this coefficient with the changing altitude
- the Lincoln Calibration Sphere (LCS)-4, a radar calibration satellite also known as Rigid Sphere-1
|Failed to separate from LCS-2
Launch dates of the OV2 sub-series
The OV2 series of satellites were built by Northrop for use with the Titan IIIC launch vehicle. The series was initially developed for the Advanced Research Environmental Test Satellite (ARENTS) programme which was intended to obtain supporting data for the Vela series but which series was cancelled.
|Photo: Author's collection
The objective of OV2-1 was to monitor biological hazards of the near Earth charged particles. It had a mass of 59 kg and fourteen instruments were carried to measure energetic particles, electromagnetic field strengths, very low frequencies and radiation effect on tissue equivalents, and included a plexiglass simulated human torso, high- and low-energy particle detectors, two plasma probes and two magnetometers. The OV2-1 was a secondary payload on what was essentially a test of the Titan IIIC launch vehicle. The payload remained attached to the second stage of the launch vehicle due to a failure of the release mechanism.
OV2-2 was to carry out optical measurements from a 400 km circular orbit to provide a better understanding of the physics of space radiation and its relation to the Sun. The satellite was to be launched in 1966 and would have carried instruments similar to those to be carried on OV2-3. The mission was cancelled when the Titan IIIC development was cancelled.
The 193 kg OV2-3 satellite carried fifteen experiments to gather data on solar and geomagnetic activity in cosmic ray and trapped particle fluxes arising from such disturbance. The satellite also tested various components from the cancelled ARENTS programme, including a solar cell array, a solid propellant rocket for satellite spin-up, cold gas jets, a solid propellant rocket for orbital maneuvers, a solar aspect sensor and two fluxgate magnetometers. The payload failed to separate from the Transtage and contact was lost after launch.
OV2-4 was to carry out optical measurements from a highly eccentric trans-lunar orbit to provide a better understanding of space radiation and its relation to the Sun. The mission was cancelled when the Titan IIIC development was cancelled.
The OV2-5 satellite collected data on the space environment at a synchronous orbit altitude, including cosmic rays, trapped particle fluxes and changes in fluxes arising from solar and geomagnetic disturbances. The payload consisted of:
- proton and electron spectrometers
- a dE/dX range telescope
- a low energy Faraday cup
- an electron detector fan
- a VLF signal antenna
- a Lyman alpha scanning photometer
- a magnetomete
- positive and negative plasma sensors
- an Orbis High beacon antenna
|Image: Author's collection
Although only seven of the twelve appendages of the satellite deployed successfully, most of the instruments provided data. OV2-5 had a mass of 204 kg. OV2-5 was part of the P67-2 launched on this flight.
|Radiation studies; Ops-1527
|Radiation studies; also known as Personnel Hazards Associated with Space Radiation (Phasr) or Ops-1427
|Ionospheric studies; also knwoin as Atmospheric Composition Satellite (Atcos)-1; failed to orbit
|Ionospheric studies; also known as Atcos-2
Launch dates of the OV3 sub-series
The Orbiting Vehicle (OV)3 series of satellites were built by Space General and were of a octagonal shape measuring 74 cm in diameter. They were used with Scout launch vehicles.
|Photo: Author's collection
OV3-1, with a mass of 68 kg, conducted radiation studies by measuring the angular distribution and energies of charged particles in the magnetosphere and upper ionosphere. It was also known as Ops-1527. The payload included proton and electron spectrometers, electrostatic analysers, plasma probes, several Geiger-Müller counters and two magnetometers.
OV3-2, with a mass of 80 kg, studied the electron and ion density and structure of the outer radiation belt and provided data on charged particle variations in the extreme upper atmosphere during the solar eclipse of 12 November 1966. Instrumentation included an electrostatic analyser to measure proton and electron spectra, an impedance probe to measure electron density, a plasma probe to measure positive and negative charged particles as well as a mass spectrometer to measure ion species.
The 75 kg OV3-3 mapped and monitored particle radiation in space with omni-directional proton/electron spectrometers, high- and low-energy hydrogen/helium nuclei telescopes, a Faraday cup electron and proton spectrometer, a medium-energy magnetic electron spectrometer and a tri-axial magnetometer.
The 79 kg OV3-4 satellite undertook radiation studies of the inner Van Allen belt and was also known as Personnel Hazards Associated with Space Radiation (PHASR) and Ops-1427. The payload consisted of a tissue equivalent radiation chamber, a linear energy transfer spectrometer, electron and proton spectrometers, a solid state charged particle spectrometer and a tri-axial magnetometer.
The objective of OV3-5, which had a mass of 94 kg, was to measure the constituents, density and temperature of the atmosphere and was also known as Atmospheric Composition Satellite (ATCOS)-1. The instruments consisted of:
- two mass spectrometers, one of which measured the composition of the neutral atmosphere and the other the ionised component
- three ion density gauges for atmospheric density measurements
- an impedance probe
Due to a failure of the fourth stage the satellite did not orbit although other references state that the first stage exploded.
OV3-6, also known as Atmospheric Composition Satellite (ATCOS)-2, measured the properties of the upper ionosphere, including its composition, density, pressure and temperature. Instruments included two mass spectrometers, three ion density gauges and an impedance probe. The satellite operated for 5 days.
|Modified Titan II stage; also known as Ops-0855
Launch dates of the OV4 sub-series
The 136 kg OV4-1R satellite was used in conjunction with OV4-1T to test the feasibility of using the ionosphere's F layer as a wave guidance for HF and VHF transmissions between satellites out of line of sight of each other. OV4-1R carried receiving equipment. The 109 kg OV4-1T satellite carried transmitters operating at 20 MHz, 34 MHz and 46 MHz. It also incorporated a small rocket motor to ensure separation from OV4-1R. The project has also been referred to as Whispering Gallery.
A second set of 'Whispering Gallery' satellites was to be launched in 1967 as OV4-2 but the programme had been cancelled along with the cancellation of the MOL programme.
The 9661 kg OV4-3 was a boiler plate model of the Manned Orbiting Laboratory (MOL) to which the reconditioned Gemini-2 (which had been used on a sub-orbital flight on 19 January 1965) was attached. The objective of the flight was to test the launch vehicle configuration as well as to qualify the MOL heat shield. The mission was also referred to as Gemini B-Heat or Project Manifold and was also known as Ops-0855. The payload included:
- a biocell experiment to study biological organism growth in zero-gravity
- an orbiting radio banking experiment to obtain ionospheric sounding data
- a zero gravity propellant gauging experiment to investigate liquid transfer under varying accelerations in space
- corner reflectors for optical measurements using collimated light reflection
- two micrometeorite detectors
- a heat transfer experiment
- a proturbance study of the attitude control nozzle and fairing aerodynamics
- an optical viewing experiment involving the vehicle's paint pattern
- the test of a hydrogen-oxygen fuel cell
|Photo: Author's collection
|Materials sciences research; also known as ERS-27
|Radiation studies; also known as ERS-28
|Radiation studies; also known as ERS-20
|Heat transfer studies; also known as ERS-21
|Radiation studies; also known as ERS-29
|Solar flare studies; also known as ERS-26
|Solar studies; cancelled
|Materials sciences research; failed to orbit
Launch dates of the OV5 sub-series
The OV5-1, -2, -3, -4, -5 and -6 satellites in this series are discussed as ERS-27, -28, -20, -21, -29 and -26 respectively (see page about the ERS series).
OV5-7 was to be launched in 1969 to measure solar radiation. Its place on a launch vehicle was taken by OV1-17A and the payload was never flown.
The 9 kg OV5-8 satellite was to conduct a materials friction experiment. The protective shroud surrounding the second stage of the launch vehicle failed to separate and the thirteen satellites, collectively referred to as SESP P68-1, were not deployed.
The 13 kg OV5-9 carried low-energy proton detectors, a dE/dx telescope, a Cerenkov counter, a VLF radiation detector, a solar X-ray monitor and a solar flare electron detector to provide further basic research data on solar radiation and its effects on the magnetosphere.
Last Updated: 12 April 2005