NSSDCA ID: 1975-052A-09
Mission Name: Nimbus 6The Nimbus 6 Pressure Modulator Radiometer (PMR) experiment took radiometric measurements in the 15-micrometer CO2 band at altitudes between 45 and 70 km on a global scale. By appropriate mathematical retrieval methods, the temperature structures of the upper stratosphere and lower mesosphere were deduced. The pressure-modulation technique permitted the extension of selective chopping techniques to higher altitudes where the pressure-broadened emission lines in the 15-micrometer CO2 band became so narrow that conventional spectrometers and interferometers had insufficient spectral resolution. In addition to pressure scanning (in discrete steps), the radiometer also employed Doppler scanning along the direction of flight. The PMR comprised two similar radiometer channels, each consisting of a plane scanning mirror, reference blackbody, pressure-modulator cell, and detector assembly. The plane mirror was gold coated and mounted at 45 deg on a 90-deg stepping motor so that the field of view of the channel could be directed to space or to the internal reference blackbody for inflight range and zero calibration. The motor was mounted on a pair of flexible pivots so that the mirror could be rotated through plus or minus 7-1/2 deg from its rest position to give the required Doppler scan. Major components in the pressure-modulator cell were a movable piston, a diaphragm, and a magnetic drive coil. The detector assembly consisted of a field lens, a condensing light pipe, and a pyroelectric flake bolometer. Each radiometer had a field of view that was 20 deg whole-angle across the spacecraft's line of flight and 40 deg whole-angle parallel to the line of flight. The derived temperature values were within 2 deg K at 65 km and about 0.2 deg K near 50 km with a vertical resolution of 10 km. For a more detailed description, see Section 8 in "The Nimbus 6 User's Guide" (TRF B23261), available from NSSDC. The instrument performed satisfactorily.
Mass: 2.3 kg
Power (avg): 3 W
Bit rate (avg): 0.01 kbps
Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office
Name | Role | Original Affiliation | |
---|---|---|---|
Dr. Guy D. Peskett | Other Investigator | Oxford University | g.peskett1@physics.oxford.ac.uk |
Dr. Clive D. Rodgers | Other Investigator | Oxford University | c.rodgers1@physics.oxford.ac.uk |
Dr. E. Jim. Williamson | Other Investigator | Oxford University | j.williamson1@physics.oxford.ac.uk |
Dr. P. Curtis | Other Investigator | Oxford University | |
Prof. John T. Houghton | Principal Investigator | Oxford University | john-houghton@seh.ox.ac.uk |