<P><H2> Introduction </H2>
<P> These PIONEERING Low Cost Mars Mission Operations initiatives during Viking, provide a unique knowledge base for future low cost, highly reliable post Viking mission operations.
<P> During 1979, NASA considered shutting down Viking Lander Mission Operations due to the decommissioning of the JPL computer that processed engineering data and to save money. However Tillman strongly proposed continuing the mission to exploit this unique opportunity to gather the first multi-year meteorology record from the surface of Mars. One major reason for this proposal was that prior to Viking, and even after the first year, conventional wisdom suggested that every year had ``great'' dust storms. By Lander 1 sol 1,100, we were well into the second Mars year past the first year's dust storm season. Although others mis-interpreted synoptic activity at the Lander 2 site for great dust storms, our continuing observations and analyses allowed us to demonstrate that there were no great dust storms similar to the first year during the second and third years, thereby rejecting the yearly great dust storm hypothesis.
<P> Another reason for continuing was that Tillman found subtle atmospheric pressure transients during late summer when normally there is very little activity, AND these transients repeated the next year. Since they occurred within 20 sols of the same season in the two years (a Mars year is 669 sols), he forecast that they would repeat next year and asked for continuous DSN coverage to begin about 1/2 year in the future. This lead to the discovery that these Martian atmospheric transients (later named ``Tillman transients'' by John Wilson) were Kelvin waves. These Lander 1 related discoveries were essential in continuing operations for 3.3 Mars years. After two years of no great dust storms, another was observed in the 4th year's dust storm season, readily justifying these efforts. The mission ended after sol 2,245 with the falilure of Viking Lander 1.
<P><H2> Mission Continuation Challenges </H2>
<P> Continuing the mission posed a problem since JPL had decommissioned the IBM 360-75 that <A HREF="http://www.atmos.washington.edu/local-httpdocs/k12/viking_history_npug_84.html#real_time_operations"> <B><I> accepted and converted raw spacecraft bits </I></B></A> to engineering data for Mission Operations and passed on science data for processing. This left no mechanism for extracting engineering or science from the raw data. To enable continued operation of Viking Lander 1, we proposed that our Viking Computer Facility take over processing of all Viking Lander engineering and our meteorology science data. This included extracting any other science and operations data from the raw downlinked spacecraft data stream and to provide all engineering data for the JPL Mission Operations staff. This included plotting all engineering parameters in the same manner we used for our data from the engineering stream. NASA agreed to continue the mission at this new, low level funding to support operations at JPL and UW. As far as is known, this was the first time any non-governmental entity provided this level of Mission Operations support for a Mars mission.
<P>At JPL, the downlink processing was carried out by two very large software packages TLMP and DECSET, written in IBM assembly language. To accomplish the transition of downlink processing from JPL to UW, TLMP and DECSET were recoded in Prime Fortran, primarily by Tom Arnold of the JPL Viking Team, and finished by Dr. Harry Edmon, and Jim Tillman of UW. The development and utilization of these resources is described in "JPL PUBLICATION 82-107, (large .pdf file), <A HREF="http://www.atmos.washington.edu/ mars/viking/lander_documents/meteorology/Pdf/JPL_Publication_82-107.pdf"> <B><I>Telecommunications and Data Acquisition Systems Support for the Viking 1975 Mission to Mars </I></B></A>. The Viking Lander Monitor Mission May 1980 to March 1983, D. J. Mudgway." This report describes our NASA Deep Space Network to Jet Propulsion Laboratory to University of Washington Viking Computer Facility engineering operations and science along with the downlink by downlink recovery attempts after the loss of data from Lander 1, on sol 2,245, <B>more than 6 Earth years</B> after landing. This is especially impressive since the Viking Lander's nominal lifetime was only 90 sols!!
Our science processing, archiving, Mission Operations functions are covered in this Memorandum of Understanding between NASA JPL and the University of Washington.
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