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The purpose of the Cosmic Background Explorer (COBE) mission was to take precise measurements of the diffuse radiation between 1 micrometer and 1 cm over the whole celestial sphere. The following quantities were measured: (1) the spectrum of the 3 K radiation over the range 100 micrometers to 1 cm; (2) the anisotropy of this radiation from 3 to 10 mm; and, (3) the spectrum and angular distribution of diffuse infrared background radiation at wavelengths from 1 to 300 micrometers.

The experiment module contained the instruments and a dewar filled with 650 liters of 1.6 K liquid helium, with a conical sun shade. The base module contained the attitude control, communications and power systems. The satellite rotated at 1 rpm about the axis of symmetry to control systematic errors in the anisotropy measurements and to allow observations of the zodiacal light at various solar elongation angles. The orientation of the spin axis was maintained anti-earth and at 94 degrees to the sun-earth line. The operational orbit was dawn-dusk sun-synchronous so that the sun was always to the side and thus was shielded from the instruments. With this orbit and spin-axis orientation, the instruments performed a complete scan of the celestial sphere every six months.

Instrument operations were terminated 1993-12-23. As of January 1994, engineering operations were to conclude that month, after which operation of the spacecraft would be transferred to Wallops for use as a test satellite.

Alternate Names

  • Cosmic Background Explorer
  • Explorer 66
  • 20322

Facts in Brief

Launch Date: 1989-11-18
Launch Vehicle: Delta
Launch Site: Vandenberg AFB, United States
Mass: 2206.0 kg
Nominal Power: 750.0 W

Funding Agency

  • NASA-Office of Space Science Applications (United States)


  • Astronomy

Additional Information

Questions or comments about this spacecraft can be directed to: Dr. David T. Leisawitz.



NameRoleOriginal AffiliationE-mail
Mr. James M. WilliamsonMission Operations ManagerNASA Goddard Space Flight
Dr. Guenter R. ReiglerProgram ManagerNASA
Dr. Daniel W. WeedmanProgram ScientistUniversity of
Dr. John C. MatherProject ScientistNASA Goddard Space Flight
Mr. Paul J. PashbyProject ManagerNASA Goddard Space Flight Center 

Selected References

Mather, J. C., et al., Early results from the Cosmic Background Explorer (COBE), Adv. Space Res., 11, No. 2, (2)181-(2)191, Feb. 1991.

Boggess, N. W., et al., COBE mission: Its design and performance two years after launch, Astrophys. J., 397, No. 2, 420-429, Oct. 1992.

US Active Archive for COBE Information/Data

The COBE Archive at LAMBDA

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