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OV1 21P with LOADS 2 mass model

The OV1 (Orbiting Vehicle 1) were small research satellite to be launched piggy back on Atlas ICBM test flights. They consisted in general of the OV1 satellite and the OV1-PM propulsion module to reach orbit. In some cases, the PM did also carry an research payload (OV1 17A, OV1 20, OV1 21).


  • OV1 17A (Orbiscal 2): ORBISCAL transmitter:
    This battery powered satellite was actually the propulsion module of OV1-17. After separation from OV1-17, this module was moved to a lower orbit by a small rocket motor and was designated OV1-17A. This spin-stabilized spacecraft, also referred to as ORBISCAL 2 carried one experiment comprising two 6.45-m-long transmitting antenna beacons and a 6.45-m-long inertia boom. The two beacons operated at 13.23 and 8.98 MHz and were used by ground station personnel to study unusual transmission by radio waves through the ionosphere. The spacecraft operated normally for one week until reentering the earth's atmosphere on 24 March 1969.
  • OV1 20P: Energetic Proton analyzer, particle flux thermal detector:
    The satellite carried two experiments -- an energetic (above 70 MeV) proton analyzer and a particle energy and thermal flux detector for measuring the electron density and temperature in the upper ionosphere. In addition, the satellite served as the launching platform for the OAR 901 spacecraft (LOADS 2). OV1-20 was cylindrical in shape, measuring 2.13 m in length and 0.6 m in diameter. A plasma probe was mounted on an approximately 1.5-m-long boom that protruded from the center of the vehicle. The spacecraft electrical systems included a 136.740 mHz telemetry transmitter, a signal conditioner, a pcm multiplexer encoder, an S-band transmitter, and a C-band transponder. Electrical power for the spacecraft and the experiments was provided by two silver-zinc batteries. To conserve power, the experiment operating sequence was controlled by an onboard timer. Only real-time data were transmitted, which limited the data acquisition to south-to-north passes between 65 deg s and 65 deg n latitude. The spacecraft performed normally after launch. All data acquisition activities were terminated on 16 August 1971, when the spacecraft's battery power pack became depleted. OV1-20 reentered the earth's atmosphere on 28 August 1971.
  • OV1 21P (DENPER): Velocity Mass spectrometer, atmospheric composition experiment, resonance cone experiment:
    It carried two known experiments – a velocity mass spectrometer that measured ion densities composition and temperature, and a VLF experiment that consisted of two 18.3-m-long ELF/VLF dipole antennas and a transreceiver that operated in 14 narrow bands and one broad band. The satellite also served as a launching platform for eight spherical research satellites (71-067D through 71-067K). OV1-21 was cylindrical in shape measuring approximately 2 m in length and 0.6 m in diameter.
Nation: USA
Type / Application: Experimental
Operator: USAF
Contractors: Convair
Power: Batteries
Orbit: 176 km × 360 km, 99.05° (#17A); 129 km × 1610 km, 91.98° (#20P); 787 km × 915 km, 87.64° (#21P)
Satellite COSPAR Date LS Launch Vehicle Remarks
OV1 17A (Orbiscal 2, P69-1) 1969-025D 18.03.1969 Va ABRES-A2 Atlas-F OV1 [LP-104] with OV1 17, OV1 18, OV1 19
OV1 20P (P70-2) 1971-067A 07.08.1971 Va BMRS-A2 Atlas-F OV1 with LOADS 2 and OV1 21, RTDS, Gridsphere 1, Gridsphere 2, Mylar Balloon, Rigidsphere, LCS 4
OV1 21P (DENPER, P70-2) 1971-067B 07.08.1971 Va BMRS-A2 Atlas-F OV1 [Star-13A] with OV1 20, LOADS 2 and RTDS, Gridsphere 1, Gridsphere 2, Mylar Balloon, Rigidsphere, LCS 4


Further STP missions: