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OFO 1, an Orbiting Frog Otolith satellite, was instrumented to obtain the first direct recordings of otolith response during prolonged periods of weightlessness. In-dwelling microelectrodes were implanted in the vestibular nerves of two bullfrogs to measure the bioelectric action potential in the animals during weightlessness and during repeated simulated gravity stimulus obtained by activation of a small centrifuge. The primary data obtained include (1) the instantaneous rate of firing from single vestibular units (data were recorded from two microelectrodes implanted in each of the frogs), (2) centrifugal acceleration profiles measured at the head of each frog, (3) EKG as a vital index of animal welfare, and (4) water environment temperature, because of the relation of temperature to vestibular activity. The instrumentation for the experiment was contained in a biopackage configured to assure survival and normal function of the two frogs for the duration of the experiment. Data were telemetered to ground stations.

Alternate Names

  • 04690
  • OFO-A
  • OFO1
  • Orbital Frog Otolith Sat
  • PL-693G

Facts in Brief

Launch Date: 1970-11-09
Launch Vehicle: Scout
Launch Site: Wallops Island, United States
Mass: 132.9 kg

Funding Agency

  • NASA-Office of Aeronautics and Space Technology (United States)


  • Life Science

Additional Information

Questions and comments about this spacecraft can be directed to: Coordinated Request and User Support Office

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