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Satellite Drag Atmospheric Density

NSSDCA ID: 1961-004A-01

Mission Name: Explorer 9
Principal Investigator:Mr. William J. O'Sullivan, Jr.


Because of its symmetrical shape, Explorer 9 was selected for use in determining upper atmospheric densities as a function of altitude, latitude, season, and solar activity. Density values near perigee were deduced from sequential observations of the spacecraft position, using optical (Baker-Nunn camera network) and radar tracking techniques. A good discussion of the general techniques used to deduce density values from satellite drag data can be found in L. G. Jacchia and J. Slowey, "Accurate drag determination for eight artificial satellites of atmospheric densities and temperatures," Smithsonian Astrophysical Observatory special report n. 100, Cambridge, Mass., July 1962. This experiment resulted in the successful determination of reasonable density values until the satellite reentered the earth's atmosphere on April 9, 1964.

Alternate Names

  • Explorer9/SatelliteDragAtmosphericDensity

Funding Agencies

  • Department of Defense-Department of the Air Force (United States)
  • NASA-Office of Space Science Applications (United States)


  • Earth Science: Atmospheric Dynamics

Additional Information

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



NameRoleOriginal AffiliationE-mail
Dr. Luigi G. JacchiaOther InvestigatorSmithsonian Astrophysical Observatory
Dr. Gerald M. KeatingOther InvestigatorNASA Langley Research Center
Mr. Claude W. Coffee, Jr.Other InvestigatorNASA Langley Research Center
Mr. William J. O'Sullivan, Jr.Principal InvestigatorNASA Langley Research Center
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