NSSDCA ID: PSPG-00814
Availability: Archived at NSSDC, accessible from elsewhere
The IRTM catalog is a file of observational sequence entries in 10 by 10 degree bins on Mars, sorted by bin number. Thus all sequences with data in a particular bin have entries in one contiguous part of the catalog. There are 650 bins: 648 10 by 10 degree bins in the Mariner 9 Mark IV scheme, and 2 landing site bins, 2 degrees square. This volume contains data from the Viking Infrared Thermal Mapper (IRTM) investigation. The two Viking orbiters were active in orbit about Mars during the years 1976 to 1980.
This data set contains the Infrared Thermal Mapping (IRTM) data of Mars acquired by the Viking orbiters. The database contains the time, geometry, and radiative parameters obtained by the IRTM instrument. Included in the database for each measurement are model temperatures of Mars; this model attempts to represent the average Martian response to the temporal variation of insolation. The reference 'Thermal and Albedo Mapping of Mars during the Viking Primary Mission', Journal of Geophysical Research, Vol. 82, No. 28, 1977, describes how the thermal emission and reflected energy measured by the various channels on the Infrared Thermal Mapper are used to reveal wide variations in the Martian surface properties. There is a description of how the surface thermal inertias are mapped and correlated with the surficial geologic units. The derivation of model and surface temperatures are described. The data set includes latitude and longitude for each measured point, as well as emission angle, solar incidence angle, the position of the sun, and other parameters that help to locate the position of the spacecraft relative to Mars. The data, software and descriptive information were produced almost entirely by the Radiometry Testbed Node of the Planetary Data System (PDS). Both the data structures and the software are descendants of the data analysis system used by the IRTM team during the Viking mission.
The data structure is similiar to that on the 1600 bpi magnetic tape set that was the basic storage and distribution form of the data from about 1980 to 1989, and from which the files on this disk were derived. These "TSDR" (time sequential data record) tapes contained only data acquired while the IRTM was pointing at or within 1.5 degrees of Mars, and hence they, and this disk, do not contain observations of Phobos or Deimos or of space. A general description of the structure of the major data files (chunks) is contained in the file [DOCUMENT]IRTMDATA.TXT. A guide to the IRTM instrument can be found in [DOCUMENT]IRTM.TXT. This file contains the same information that is in the PDS catalog (and in VOLDESC.SFD on this disk) but with the machine-readable template structure removed. The bulk of the software on this disk is under the [SOFTWARE.RAD] directory and is the same as the "XG" system delivered to the PDS. The file [DOCUMENT]SOFTWARE.TXT contains a brief introduction to this software, and an outline of its directory structure. The [SOFTWARE.RAD.DOC...] directory contains extensive documentation of the software system; in particular, XGSDD.MEM contains the Software Design Document and XGUG.MEM contains the User Guide (these are large files). The IRTM Catalog ([CATALOG]IRTMCAT.DAT) is an independent dataset containing entries for each sequence in each of 650 10 by 10 degree bins on Mars. [DOCUMENT]IRTMCAT.TXT is a user's guide. [SOFTWARE.CAT]PRCAT.FOR is a program for reading the catalog. In addition, there is an ASCII table file (CHUNK.DAT) which contains information about each data file, and two binary table files (VO1ORBIT.DAT and VO2ORBIT.DAT) which contain time and geometry information about each orbit in the mission. These are in the [INDEX] directory. These data are available on-line from the Planetary Data System (PDS) at: http://pds-geosciences.wustl.edu/viking/vo1_vo2-m-irtm-4-v1/old_vo_0001/
Questions and comments about this data collection can be directed to: Dr. David R. Williams
Name | Role | Original Affiliation | |
---|---|---|---|
Dr. Steven W. Lee | General Contact | University of Colorado | steven.lee@colorado.edu |