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Electrically Scanning Microwave Radiometer (ESMR)

NSSDCA ID: 1972-097A-04

Mission Name: Nimbus 5
Principal Investigator:Dr. Thomas T. Wilheit, Jr.


The primary objectives of the Nimbus 5 Electrically Scanning Microwave Radiometer (ESMR) were (1) to derive the liquid water content of clouds from brightness temperatures over oceans, (2) to observe differences between sea ice and the open sea over the polar caps, and (3) to test the feasibility of inferring surface composition and soil moisture. To accomplish these objectives, the ESMR was capable of continuous global mapping of the 1.55-cm (19.36 GHz) microwave radiation emitted by the earth/atmosphere system, and could function even in the presence of cloud conditions that block conventional satellite infrared sensors. An 83.3- by 85.5-cm radiometer antenna system, deployed after launch, scanned the earth successively at various angles in a plane perpendicular to the spacecraft orbital track, producing a brightness-temperature map of the surface of the earth and its atmosphere. The scanning process was controlled by a computer on board, and it consisted of 78 symmetrically distributed independent scan spots extending 50 deg to either side of nadir. Angular separation of the scan spots allowed for an 8.5% overlap between view positions. From a mean orbital height of 1100 km, the radiometer had an accuracy of about plus or minus 1 deg C with a spatial resolution of about 25 km at nadir. The ESMR data were stored on magnetic tape for transmission to ground acquisition stations. For more detailed information, see Section 4 in "The Nimbus 5 User's Guide" (TRF B14758). Selected ESMR images were presented in "The Nimbus 5 Data Catalog." Both documents are available from NSSDC.

Alternate Names

  • ESMR
  • Mapping Earth Rad. and Cloud Struc. with an Elec. Scanning Microwave Radiometer
  • Nimbus5/ESMR

Facts in Brief

Mass: 28 kg
Power (avg): 40 W
Bit rate (avg): 0.4 kbps

Funding Agency

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


  • Earth Science: Atmospheric Dynamics
  • Earth Science: Land Surface Processes
  • Earth Science: Physical Oceanography

Additional Information

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



NameRoleOriginal AffiliationE-mail
Dr. Per GloersenOther InvestigatorNASA Goddard Space Flight
Dr. Thomas T. Wilheit, Jr.Principal InvestigatorNASA Goddard Space Flight
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