OV5 was a version of the USAF Environmental Research Satellites dedicated to radiation research and VLF plasma wave detection. The octagonal Environmental Research Satellites were designed for piggyback launching from large primary mission vehicles. Ranging in mass from 0.7 to 45 kg, and carrying from 1 to 14 experiments, the ERS spacecraft provided an inexpensive, flexible vehicle capable of making scientific and engineering measurements in space.

A major role of the ERS satellites was to act as a test bed to determine the reliability of improved components and subsystems destined for use in later generations of spacecraft. A unique feature of the system was its capability to function without a battery. The key to this advantage was the design which permitted solar cells, fastened to all exterior surfaces of the vehicle, to maintain constant exposure of about 15 percent of the sun. The ERS was a small satellite, measuring in one version only 22 cm on a side and weighing 680 g; the larger version weighed 45 kg and was a 51 cm diameter cylinder. The 8-sided version was designated the OV-5 and became a part of a program conducted by the Air Force Office of Aerospace Research. Prime Contractor was TRW Systems Group of TRW Inc.

Typical orbit: 33179 x 71530 km, 27.8 deg inclinaton.

• 1967 April 28 - OV5-03 - Launch Site: Cape Canaveral. Launch Complex: LC41. Launch Vehicle: Titan. Mass: 9.00 kg (19.80 lb). Perigee: 8,604 km (5,346 mi). Apogee: 111,229 km (69,114 mi). Inclination: 32.80 deg. Period: 2,829.60 min.
  Radiation research; deployed ERS 20. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

• 1967 April 28 - OV5-01 - Launch Site: Cape Canaveral. Launch Complex: LC41. Launch Vehicle: Titan. Mass: 9.00 kg (19.80 lb). Perigee: 8,979 km (5,579 mi). Apogee: 110,746 km (68,814 mi). Inclination: 32.80 deg. Period: 2,827.80 min.
  Materials research; deployed ERS 27. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

• 1968 August 16 - OV5-8 - Launch Site: Vandenberg. Launch Complex: SLC3E. Launch Vehicle: Atlas. FAILURE: Failure.
  

• 1968 September 26 - OV5-04 - Launch Site: Cape Canaveral. Launch Complex: LC41. Launch Vehicle: Titan. Mass: 13 kg (28 lb). Perigee: 35,775 km (22,229 mi). Apogee: 35,786 km (22,236 mi). Inclination: 3.00 deg. Period: 1,435.80 min.
  Examined heat transfer in liquids in zero-g. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A). Last known longitude (19 July 1995) 138.85 deg E drifting at 0.103 deg W per day.

• 1968 September 26 - OV5-02 - Launch Site: Cape Canaveral. Launch Complex: LC41. Launch Vehicle: Titan. Mass: 10 kg (22 lb). Perigee: 184 km (114 mi). Apogee: 35,786 km (22,236 mi). Inclination: 26.40 deg. Period: 630.80 min.
  Particle radiation data. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

• 1969 May 23 - OV5-05 - Launch Site: Cape Canaveral. Launch Complex: LC41. Launch Vehicle: Titan. Mass: 259 kg (570 lb). Perigee: 59,630 km (37,050 mi). Apogee: 69,130 km (42,950 mi). Inclination: 33.00 deg. Period: 3,121.90 min.
  Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

• 1969 May 23 - OV5-06 - Launch Site: Cape Canaveral. Launch Complex: LC41. Launch Vehicle: Titan. Mass: 259 kg (570 lb). Perigee: 59,540 km (36,990 mi). Apogee: 69,022 km (42,888 mi). Inclination: 33.60 deg. Period: 3,115.40 min.
  Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).

• 1969 May 23 - OV5-09 - Launch Site: Cape Canaveral. Launch Complex: LC41. Launch Vehicle: Titan. Mass: 11 kg (24 lb). Perigee: 59,543 km (36,998 mi). Apogee: 69,011 km (42,881 mi). Inclination: 33.50 deg. Period: 3,115.10 min.
  VLF plasma wave detection. Space craft engaged in investigation of spaceflight techniques and technology (US Cat A).