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NSSDCA ID: 1959-007A-03

Mission Name: Vanguard 3
Principal Investigator:Mr. Herman E. Lagow


This experiment contained two sealed pressure zones, extending along the interior walls of the satellite, which were designed to record the impact of micrometeorites large enough to pierce the satellite shell. These pressure zones were partial vacuums, each at a different pressure, and were protected by 6.6E-2 cm magnesium walls that presented an exposed surface area of 0.162 sq m, which was 20% of the area of the shell. A puncture in the walls of either zone was detected by a differential pressure gauge mounted between them, and telemetered as a change in the length of one of the telemetry channels. Erosion of the satellite shell through bombardment by dust, micrometeorites, and other particles was recorded by three chromium-strip erosion gauges mounted on the satellite surface, and by a photosensitive detector. Electrical resistances of the gauges changed as their surfaces were changed by erosion. The photosensitive detector, a cadmium-sulfide cell protected by an opaque covering of mylar plastic and deposited aluminum, also showed a resistance change as the covering was eroded or penetrated. Erosion measurements also were telemetered as channel lengths, which permitted estimates of the erosion rates. Four barium-titanate-type microphones recorded micrometeorite impacts on the satellite's surface. The microphone output was amplified, shaped, and fed into a magnetic counter unit, which provided continuously, in three-decimal digits, the cumulative count of impacts. The unit counted up to 1.E3 and then reset to zero. The satellite recorded 6.6E3 micrometeorite impacts during 66 days of operation, of which 2.8E3 occurred during a 70-h interval from November 16 to 18, 1959 (The time of the Leonid meteor shower). No penetrations or fractures were recorded in the sensors of the surface penetration experiment. Because the erosion sensors were not disrupted, no definite results could be drawn from that experiment.

Alternate Names

  • Vanguard3/Micrometeorite


  • Planetary Science: Small Bodies

Additional Information

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



NameRoleOriginal AffiliationE-mail
Mr. Herman E. LagowPrincipal InvestigatorNASA Goddard Space Flight Center

Selected References

  • Schaefer, D. H., Satellite micrometeorite counter, Unpublished, Unnumbered, Undated.
  • Alexander, W. M., et al., Interplanetary dust particles of micron-size probably associated with the Leonid meteor stream, J. Geophys. Res., 66, No. 11, 3970-3973, doi:10.1029/JZ066i011p03970, Nov. 1961.
  • Alexander, W. M., and H. E. Lagow, Recent direct measurements of cosmic dust in the vicinity of the earth using satellites, Space Res., 1, 1033-1041, 1960. (Proc. of the 1st Intern. Space Sci. Symp., Nice, France, Jan. 11-16, 1960).
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