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Satellite Drag Atmospheric Density

NSSDCA ID: 1964-004A-03

Mission Name: Echo 2
Principal Investigator:Dr. Luigi G. Jacchia


Because of its symmetrical shape, Echo 2 was selected by the experimenters for use in determining upper atmospheric densities as a function of altitude, latitude, season, and solar activity. This experiment was not planned prior to launch. Density values near perigee were deduced from sequential observations of the spacecraft position, using optical (Baker-Nunn camera network) and radio and/or radar tracking techniques. A good discussion of the general techniques used to deduce density values from satellite drag data can be found in "Smithsonian Astrophysical Observatory Special Report No. 100," by L.G. Jacchia and J.R. Slowey. This experiment resulted in the successful determination of reasonable density values until the spacecraft re-entered the earth's atmosphere on June 7, 1969.

Alternate Names

  • Echo2/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. Jack W. SloweyOther InvestigatorSmithsonian Astrophysical Observatory
Dr. Luigi G. JacchiaPrincipal InvestigatorSmithsonian Astrophysical Observatory
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