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Particle Detector

NSSDCA ID: 1962-041A-07

Mission Name: Mariner 2
Principal Investigator:Prof. James A. Van Allen


A collimated, directional, Anton type 213 Geiger-Mueller tube (with energy thresholds of 40 keV for electrons and 500 keV for protons) was used to search for charged particles magnetically trapped in the vicinity of the planet Venus and, if such particles were found, to obtain preliminary measurements of their spatial distribution and intensity. Throughout the flight, including the planetary flyby, the axis of the detector's conical field of view (90 degree full angle) was directed at 70 degree +/- 1 degree to the spacecraft-sun line. This axis lay in the plane containing the Sun, Earth, and spacecraft and was on the earthward side of the spacecraft. During the 3.5 month interplanetary mode of operation, the radiation equipment was used to monitor the intensity of low-energy particles. The accumulated number of counts from the detector during a 9.60 s interval was read out once each 887 s. During the encounter mode, the accumulated number of counts during a 9.60 s interval was read out once each 484 s. There was an absence of any discernible increase in counting rate during passage by Venus at radial distances as small as 41,000 km on the sunward side of the planet.

Alternate Names

  • Mariner2/ParticleDetector

Facts in Brief

Mass: 0.06 kg
Power (avg): 0.3 W


  • Planetary Science: Fields and Particles
  • Space Physics: Heliospheric Studies

Additional Information

Questions and comments about this experiment can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Prof. James A. Van AllenGeneral ContactUniversity of Iowa
Prof. James A. Van AllenPrincipal InvestigatorUniversity of Iowa

Selected References

  • Van Allen, J. A., and L. A. Frank, The mission of Mariner II: Preliminary observations, the Iowa radiation experiment, Science, 138, No. 3545, 1095-1097, doi:10.1126/science.138.3545.1097, Dec. 1962.
  • Frank, L. A., et al., Mariner II: Preliminary reports on measurements of Venus, charged particles, Science, 139, No. 3558, 905-907, doi:10.1126/science.139.3558.905, Mar. 1963.
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