Instrument Testing
Mission Operations
Meteorological Data

James E. Tillman, Director
Viking Computer Facility
Dept. Atmospheric Sciences
University of Washington

Instrument Testing

In 1974, Tillman requested of the Viking Meteorology Science Team and the Project, that additional tests be performed on the Viking Wind Sensor assembly. The sensor had only been tested over 240 degrees of azimuth, and in a tunnel (tube) so small that only the wind part of the sensor assembly could be installed and corrections for the proximity of the wall were required to use these data. These tests were funded, designed and carried out by NASA Langley Research Center, Martin Marietta Aerospace, TRW, and the University of Washington, assisted by National Center for Atmospheric Research staff. Tillman and his UW staff developed a computer facility, the Viking Computer Facility, to operate the Viking Meteorology Instrument System, VMIS, with the same interface as Viking Landers Guidance and Sequencing Computer, GCSC, and gather wind tunnel data. See Chamberlain et al., 1976, for a description of the meteorology experiment and mission.

Viking Mission Operations

After development for VMIS system testing, the computer system was upgraded to a Prime 400, the first, very large scale, low cost computer system with program size capabilities greater than most mainframes at that time. The facility and software were enhanced to run the full Viking Meteorology software suite, and later the Lander Mission Operations engineering software. All of the primary Viking meteorological products, and essentially all of the Mars meteorological products archived at NSSDC and PDS, were produced on the Viking Computer Facility or by its staff. Examples are the Daily Average Pressure, the "Binned and Splined" wind, temperature and pressure data. All raw meteorology data were assembled and archived on it, and after sol 999 produced by it, for the mission and subsequent products. Between 1976 and 1982, the end of the mission, tape certification software developed by the VCF and utilized to maintain the archives, resulted in ZERO lost science and engineering data out of many hundreds of tapes.

This computer facility is still operational and maintained by Jim Tillman and Harry Edmon and is being used to process, analyze and display Viking meteorological, engineering and other and spacecraft data. Viking Mission Operations is a short history of our development of this first low cost, planetary mission operations spacecraft data processing facility.

Meteorological data and documents

Much of the data, and information below, and to be added and linked here, formerly were available only on the VCF's Prime computer. Major segments of the Viking Meteorological data, especially Lander 1 data after the partial failure of the wind sensor, have not been processed, (let alone analyzed), due to the lack of human and computational resources in the past. With the renewed interest in Mars, it is important that they be recovered, processed, analyzed and documented for posterity. Incomplete analyses of some of the VL-1 data seem to provide insight into one of the major terrestrial climate questions while advances in computer hardware and storage aleviate many of the prior computational roadblocks.

Atmospheric Pressure at Viking Landers 1 & 2.

These atmospheric pressure plots illustrate the major year to year similarities and differences in atmospheric phenomena during the 3.3 years, July 20, 1976 to Nov 12 1982, that the Viking Landers operated on the surface of Mars. Highlights are indicated in the accompanying text along with references to comprehensive analyses. Regional, hemispheric and global scales are reflected as are variations over time scales ranging from a few sols (Martian day), to inter annual scales. For A More Complete Description of these daily average statistics and the associated atmospheric phenomena, see Tillman 1985, 1988, Zurek et al., 1992, and Tillman, Johnson, Guttorp and Percival, 1993.

Atmospheric Pressure at Viking Landers 1 & 2

(Please click on the plots for a high resolution version.)
(© J. E. Tillman, 1985, 1988, 1997. These figures may be used
under the conditions described herein and in referenced materials.)

These comments are targeted for Atmospheric scientists.
Important processes reflected in the above figure are:

First year Second year Third year Fourth year

(Please click on the plots for a high resolution version.)
(© J. E. Tillman, 1985, 1988, 1997. These figures may be used
under the conditions described herein and in referenced materials.)

Viking Missions Atmospheric Pressure
superimposed on a one year timeline

Lower panel

Conclusion: In the northern hemisphere, the Martian atmosphere varies greatly from year to year during the dust storm seasons while at other seasons, most phenomena are remarkably similar from year to year. Zurek et al. 1992 provide the most comprehensive description of Martian meteorology and list of references.

Copyright J. E. Tillman, University of Washington, 1994.

Permission is granted to use these plots in any presentation or publication provided: 1) The figure caption contains "courtesy of J. E. Tillman, University of Washington, Dept. Atmospheric Sciences" and 2), the Tillman 1985, 1988 references are included in any abstract, publication or report. A copy of the publication, report or talk abstract is requested. Data availability are described in: References and Availability. PostScript versions of the plots of pressure: Mars years overlayed and the non-overlayed time series can be obtained via these anonymous FTP links.

The Software used in the analysis and plotting of the data were created by William Guest, Neal Johnson Charlie Strauss and Jim Tillman.

Last revision 13 April, 2002