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Infrared Interferometer Spectrometer (IRIS)

NSSDC ID: 1977-076A-03
Mission Name: Voyager 2
Principal Investigator: Dr. Rudolf A. Hanel


This investigation was carried out using a Michelson interferometer and a single-channel radiometer similar in design to the Mariner 9 IRIS, combined into a single instrument. The investigation studied both global and local energy balance. Atmospheric composition was also investigated, including determination of the H2/He ratio, and the abundance of CH2 and NH3. Vertical temperature profiles were obtained on the planets and satellites with atmospheres. Studies of the composition, thermal properties, and size of particles in Saturn's rings were conducted. The interferometer had a spectral range of approximately 180 to 2500 1/cm (4-55 micrometers), while the radiometer range covered the spectra from approximately 5000 to 30000 1/cm (0.33-2 micrometers). The nominal apodized spectral resolution of the interferometer was 4.3 1/cm. The instruments shared a half-meter Cassegrain telescope with a 0.25-deg field of view. The basic quantity measured was the spectral radiance of emitted and reflected IR radiation and a large fraction of reflected visible energy. The interferometer was calibrated using deep space (assumed to be a black body at 0 deg K) and the internal instrument temperature as reference points. The radiometer was calibrated with a diffuser plate of known radiometric properties. For a description of the instrument see Hanel, R. et al., 1977, Applied Optics, v. 19, p. 1391.

Alternate Names

  • IRIS

Facts in Brief

Mass: 19.47 kg
Power (avg): 12.0 W
Bit rate (avg): 1.12 bps

Funding Agency

  • NASA-Office of Space Science (United States)


  • Planetary Science: Atmospheres
  • Planetary Science: Geology and Geophysics

Additional Information

Questions or comments about this experiment can be directed to: Dr. Edwin V. Bell, II.



NameRoleOriginal AffiliationE-mail
Dr. Barney J. ConrathCo-InvestigatorNASA Goddard Space Flight Center 
Dr. Joseph A. PirragliaCo-InvestigatorNASA Goddard Space Flight Center 
Mr. Virgil G. KundeCo-InvestigatorNASA Goddard Space Flight
Dr. William C. MaguireCo-InvestigatorNASA Goddard Space Flight
Dr. Santosh KumarCo-InvestigatorUniversity of Southern California 
Dr. Dale P. CruikshankCo-InvestigatorUniversity of
Dr. Robert E. SamuelsonCo-InvestigatorNASA Goddard Space Flight
Dr. Peter J. GieraschCo-InvestigatorCornell
Dr. Cyril A. PonnamperumaCo-InvestigatorUniversity of Maryland 
Dr. F. Michael FlasarCo-InvestigatorNASA Goddard Space Flight
Dr. Daniel GautierCo-InvestigatorObservatoire de Paris,
Dr. Rudolf A. HanelPrincipal InvestigatorNASA Goddard Space Flight Center 
Dr. John C. PearlCo-InvestigatorNASA Goddard Space Flight

Selected References

Conrath, B. J., et al., Thermal structure and dynamics of Neptune's atmosphere from Voyager measurements, J. Geophys. Res., 96, Suppl., 18931-18939, Oct. 1991.

Hanel, R., et al., Infrared observations of the Saturnian system from Voyager 2, Science, 215, No. 4532, 544-548, Jan. 1982.

Hanel, R., et al., Infrared observations of the Jovian system from Voyager 2, Science, 206, No. 4421, 952-956, Nov. 1979.

Hanel, R., et al., Infrared observations of the Uranian system, Science, 233, No. 4759, 70-74, July 1986.

Hanel, R., et al., The Voyager infrared spectroscopy and radiometry investigation, Space Sci. Rev., 21, No. 2, 129-157, Nov. 1977.

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