Charged Particles

@article{Frank1963ChargedP,
  title={Charged Particles},
  author={Louis A. Frank and James A. Van Allen and Howard Kent Hills},
  journal={Science},
  year={1963},
  volume={139},
  pages={905 - 907}
}
There was a complete absence of charged particles associated with the planet Venus at radial distances as small as 41,000 km on the sunward side of the planet. This result is taken to mean that the magnetosphere of Venus, if any, does not extend to that great a distance. The most plausible interpretation is that (MV/ME) ≤ 0.18, where MV and ME are the dipole magnetic moments of Venus and Earth, respectively. The results are consistent with MV/ME = 0. Certain qualifications prevent this… 

References

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This work was supported in part by the Jet Propulsion Laboratory and by our NASA grant NsG-233-62. We are particularly indebted to Conway W
for essential assistance with many aspects of the work and to C. S. Wang (State University of Iowa) for assistance with data reduction. Two of us