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Mariner 9 IRIS Spectral Observations of Mars (PDS)


Availability: At NSSDC, Ready for Offline Distribution (or Staging if Digital)

Time span: 1971-11-14 to 1972-09-17


This dataset contains measurements from the Mariner 9 infrared interferometer spectrometer (IRIS) and ancillary data. Each record of the dataset consists of a header and a spectral observation of Mars. The header contains pointing and other information on the geometry of the observation. The spectral data consist of calibrated thermal emission spectra expressed as spectral radiances in Watt/cm**2/sr/cm**-1.

The dataset is ordered by time as measured by the Data Acquisition System (DAS) time (1 DAS count is approximately 1.2 sec.) Two IRIS frames are completed every 35 DAS counts; every eighth IRIS frame is devoted to a calibration observation (alternately of interstellar space and an internal calibration blackbody), and is therefore absent from the calibrated dataset. The wavenumber corresponding to each spectral radiance value is not included in the dataset; the beginning wavenumber and the constant wavenumber increment are given, permitting easy calculation of the appropriate wavenumber for each radiance.

The calibrated radiances have been obtained from the directly measured interferograms of Mars. The interferograms are first symmetrized to correct for the fact that they are not sampled at zero path difference, and to remove the asymmetry due to residual dispersion in the beamsplitter and compensator. The symmetrized interferograms are the apodized using a Hamming function, and are cosine transformed. The responsivity obtained from the deep space and internal blackbody measurements is then used to obtain calibrated radiances.

Due to the geometry of the Mariner 9 orbit and location of ground stations, most spectra included are from the even numbered orbits. Additionally, after 107 days the changing Mars-Earth alignment allowed only recorded data to be sent at specified times, so only a small amount of data were received from this time until th end of mission.

The data are stored in a single file in binary form with the number of records and record structure documented in a detached PDS label. There is also a single calibration binary file with detached label. The disk is formatted according to the ISO 9660 level 1 Interchange Standard. This disk has ID USA_NASA_PDS_MR9_1001 and contains PDS dataset MR9-M-IRIS-3-RDR-V1.0.

Alternate Names

  • PDS MR9-M-IRIS-3-RDR-V1.0
  • MR9-M-IRIS-3-RDR-V1.0


  • Planetary Science: Geology and Geophysics


  • 71-051A-03C

Additional Information



Questions and comments about this data collection can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Dr. John C. PearlData ProviderNASA Goddard Space Flight
Dr. Lyle F. HuberGeneral ContactNew Mexico State
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