definition |
- [Source: National Space Science Data Center, http://nssdc.gsfc.nasa.gov/nmc/experimentDisplay.do?id=1969-037A-05 ]
The Nimbus 3 Medium-Resolution Infrared Radiometer (MRIR) experiment measured the intensity and distribution of the electromagnetic radiation emitted by and reflected from the earth and its atmosphere in five selected wavelength intervals from 0.2 to 23 micrometers. Data on the heat balance of the earth-atmosphere system were obtained as well as water vapor distribution data, surface or near-surface temperatures, and data on seasonal changes of stratospheric temperature distribution. The five wavelength regions were (1) the 6.5- to 7.0-micrometer channel, which covered the 6.7-micrometer water vapor absorption band, (2) the 10- to 11-micrometer band, which operated in the atmospheric window, (3) the 14.5- to 15.5-micrometer band, which covered the 15-micrometer carbon dioxide absorption band, (4) the 20- to 23-micrometer channel, which covered the spectral region containing the broad rotational absorption bands of water vapor, and (5) the 0.2- to 4.0-micrometer channel, which yielded information on the intensity of reflected solar energy. Radiant energy from the earth was collected by a flat scanning mirror inclined at 45 deg to the optical axis. The mirror rotated at 8 rpm and scanned in a plane perpendicular to the direction of motion of the satellite. Each of the five channels contained a 4.33-cm diameter folded telescope with a 2.8-deg field of view and a thermistor bolometer. The collected energy was modulated by a mechanical chopper to produce an ac signal. The signal was then amplified and recorded on magnetic tape for subsequent playback to a ground acquisition station. At a satellite altitude of 1100 km, a horizontal resolution of 45 km was obtained. The MRIR experiment was successful, in spite of a telemetry conflict that caused the experiment to be periodically turned off. During August and September 1970 (hurricane season), the MRIR was on essentially full time to cover the area from the equator to 70 deg N and from 10 deg E to 100 deg W. On September 25, 1970, the satellite's rear horizon scanner failed, making it impossible to determine where the MRIR sensor was pointing. The experiment was operated periodically until January 22, 1972, when all spacecraft operations were terminated.
Group: Instrument_Details
Entry_ID: MRIR/NIMBUS-3
Group: Instrument_Identification
Instrument_Category: Earth Remote Sensing Instruments
Instrument_Class: Passive Remote Sensing
Instrument_Type: Spectrometers/Radiometers
Instrument_Subtype: Radiometers
Short_Name: MRIR/NIMBUS-3
Long_Name: Medium-Resolution Infrared Radiometer on NIMBUS-3
End_Group
Group: Associated_Platforms
Short_Name: NIMBUS-3
End_Group
Group: Spectral_Frequency_Information
Wavelength_Keyword: Infrared > Thermal
Spectral_Frequency_Coverage_Range: 6.5 μm - 7.0 μm
End_Group
Group: Spectral_Frequency_Information
Wavelength_Keyword: Infrared > Thermal
Spectral_Frequency_Coverage_Range: 10 μm - 11 μm
End_Group
Group: Spectral_Frequency_Information
Wavelength_Keyword: Infrared > Thermal
Spectral_Frequency_Coverage_Range: 14.5 μm - 15.5 μm
End_Group
Group: Spectral_Frequency_Information
Wavelength_Keyword: Infrared > Thermal
Spectral_Frequency_Coverage_Range: 20 μm - 23 μm
End_Group
Group: Spectral_Frequency_Information
Wavelength_Keyword: Infrared > Reflected
Spectral_Frequency_Coverage_Range: 0.2 μm - 4.0 μm
End_Group
Online_Resource: http://nssdc.gsfc.nasa.gov/nmc/experimentDisplay.do?id=1966-040A-03
Online_Resource: http://nasascience.nasa.gov/missions/nimbus
Online_Resource: http://atmospheres.gsfc.nasa.gov/nimbus/
Group: Instrument_Logistics
Instrument_Owner: USA/NASA
End_Group
End_Group
|