NASA Logo, National Aeronautics and Space Administration
NASA Space Science Data Coordinated Archive Header

High-Resolution Infrared Radiometer

NSSDCA ID: 1966-040A-03

Mission Name: Nimbus 2
Principal Investigator:Dr. L. L. Foshee


The Nimbus 2 High-Resolution Infrared Radiometer (HRIR) was designed (1) to map the earth's nighttime cloud cover and thus to complement the daytime television (AVCS) coverage and (2) to measure the radiative temperatures of cloud tops and surface terrain. Mounted on the earth-oriented sensory ring, the radiometer measured thermal radiation in the 3.5- to 4.1-micrometer "window" region. The HRIR subsystem consisted of (1) an optical system, (2) an infrared detector (lead selenide photoconductive material), (3) electronics, (4) a magnetic tape recorder, and (5) a filter to minimize attenuation effects of water vapor and carbon dioxide. In contrast to the AVCS camera, no image was formed within the radiometer. The HRIR sensor merely transformed the received radiation into an electrical voltage, which was recorded on the tape recorder for subsequent playback when the satellite came within range of an acquisition station. Some HRIR data were also transmitted in a real-time mode by the APT transmitter. The radiometer had an instantaneous field of view of about 0.5 deg, which at an altitude of 1100 km corresponded to a ground resolution of approximately 8 km at nadir. The radiometer was capable of measuring radiance temperatures from 210 to 330 K. Since it operated in the 3.5- to 4.1-micrometer region, the daytime pictures included reflected solar radiation in addition to the emitted surface IR radiation. However, the reflected solar radiation did not saturate the instrument, and a usable output was still obtained. The experiment was a success, and good data were obtained until the HRIR tape recorder failed on November 15, 1966. The failure of the spacecraft recorder on July 26, 1966, necessitated the use of the HRIR recorder on a part-time basis to record selected telemetry data, which resulted in a 15% reduction of available HRIR data thereafter. For more detailed information of the experiment and the index of data, see Section 3 of "Nimbus II Users' Guide" (TRF B03406), "The Nimbus II High Resolution Infrared Data World Montage Catalog" (TRF B06578), and "The Nimbus II Data Catalog" (TRF B06573), available from NSSDC.

Alternate Names

  • HRIR
  • Nimbus2/HRIR

Facts in Brief

Mass: 5 kg
Power (avg): 4 W

Funding Agency

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


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

Additional Information

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



NameRoleOriginal AffiliationE-mail
Dr. L. L. FosheePrincipal InvestigatorUS Army Electronics Command
[] NASA Logo -