The Viking Mission to Mars

                             James E. Tillman

                      Viking Meteorology Science Team
                    Director, Viking Computer Facility
                         University of Washington
                           Seattle, Wash., 98195

		  	      Keynote Address
		Prime Computer Users Group National Meeting
			    Orlando, Fla. 1984

1 Introduction

The planet Mars has often stimulated  the  imagination  and  curiosity  of
mankind.  With  the  following  material,  I  hope  to  show  some  of the
intriguing aspects of the planet, as observed from  Earth,  aspects  which
generated a  strong  desire  to  observe  and  explore the surface.  These
Earthbound observers have long known that Mars has seasonal changes,  with
dust storms  and  a  varying  polar  cap.   As its atmospheric and surface
conditions most resemble those  of  Earth,  when  compared  to  the  other
planets in  our  solar system, the possibility of life and its relation to
terrestrial forms, provided a major portion of the scientific impetus  for
the Viking  Mission  to  Mars.   The  Viking  Mission to Mars was the most
complex scientific exploration of any planet other than Earth conducted by
mankind.  In the sophistication of the remotely operated  instrumentation,
it surpasses  even  the  Apollo  Lunar  Missions.   Due to the exceptional
effort of its engineering, management, operations and  scientific  staffs,
it exceeded by far the design goals and expected lifetimes of the systems.
For example, Lander 1, the Thomas Mutch Memorial Station, ceased operation
after 2,245 sols ( 2,306 days ) on Mars, which should be compared with its
designed lifetime  of  approximately 120 sols.  In the following segments,
some of  the  highlights  of  the  Viking  exploration  of  Mars  will  be
presented.  Some  of the interesting aspects of our use of Prime computers
for the Viking program will be discussed as well  as  our  acquisition  of
hardware for  and  development of the computer driven display, "The Viking
View of Mars" for the Smithsonian National Air  and  Space  Museum.   This
permanent exhibit  presents  text,  graphics and images for the public and
should be on display during this meeting.

2 Mars
      2.1 Observations of Mars from Earth

   Several characteristics of Mars have contributed to our interest in  it
   since prehistoric times.  It has a redish color, it is easy to observe,
   its motions  are  not a simple circurlar orbit and, since the invention
   of the telescope, it has been observed to undergo significant  seasonal
   changes.  Seasonal  changes  of  major  interest are its development of
   polar caps, the differences in its albedo, or contrast, on a day to day
   and year to year basis, and the identification of  linear  features  on
   the surface  as  "canale",  singular  ( Father Secchi ), about 1869 and
   "canali", plural ( Schiaparelli ) about 1877.  Percival Lowell seems to
   have pushed the linear features to the extermes  of  artistic  endeavor
   and speculation, in that in 1908 he published a book "Mars as the Abode
   of Life"  wherein  he  speculated  that  the  canals  were  the work of
   "intelligent creatures, alike to us in spirit,  though  not  in  form."
   The possibility  of  life,  but at a far more primitive level than that
   envisioned by Lowell,  was  a  major  aspect  of  the  Viking  Mission.
   Although  we  have  not  detected  life  on  the  planet,  it  has  the
   environmental characteristics most similar to  Earth  and  consquently,
   most likely of the other planets or moons to support life.  However, as
   meteorologists, our observations from the surface of Mars have provided
   information, conclusions,  new phenomena and speculations far beyond my
   hopes or even dreams at the beginning of the mission.

   Scintillation in the atmosphere due to temperature  variations,  limits
   the resolution  of  Earth  based  astronomical  observations  such that
   telescopes of a few inches diamater provide as high resolution  as  can
   be simply  obtained:   larger telescopes are constructed to view dimmer
   objects.  However, Earth based observations are valuable in that we  do
   not currently  have  any  active  spacecraft  at Mars and we have found
   important year to year  differences  in  ths  climate  of  Mars.   They
   suppliment our Mariner and Viking observations by providing data on the
   seasons in  which  dust  storms  form  and some information as to their
   extent and intensity.  Since Mars is too  far  from  earth  for  useful
   observations most  of  the year, these data can not be very continuous,
   even if the weather were always cooperative.

   2.2 Pre Viking spacecraft observations

   The first close observations of Mars by NASA spacecraft began with  the
   Mariner 4  flyby  in  1965  which  took  21  photographs.   Each  photo
   contained 240,000 bits of data, transmitted to Earth at 8.33  bits  per
   second.  Mariner 4 showed craters and a thin haze in the Carbon Dioxide
   atmosphere.  Two  later Mariner flyby's in 1969, mainly revealed only a
   cratered terrain  without  major  geological  features.   However,  the
   observations of  the  Mariner  9 orbiter soon changed the perception of
   Mars.  During approach, a small dust storm in the  southern  hemisphere
   developed into  an intense global dust storm, injecting dust to heights
   well above 30 kilometers.  At the most intense period,  only  a  small,
   low contrast  feature  could  be  seen.   Once  the  dust cleared, this
   feature was revealed to be a volcano, Olympus Mons, whose  top  was  29
   kilometers above  mean Mars level!  Other interesting features were the
   chain of three other volcanoes almost as high as  Olympus  Mons  and  a
   canyon system 5,000 kilometers long, up to 200 kilometers across and up
   to 7  kilometers  deep.  Since the diamater of Mars is only 53% that of
   earth, these large canyons and volcanoes seem even more  dramatic.   At
   its base, the diamater of Olympus Mons is more than 500 kilometers.  In
   the next  section, some of the highlights of the Viking Mission to Mars
   will be covered.

3 The Viking Mission to Mars

The Viking Mission was the most ambitious  planetary  expolration  program
undertaken by NASA or by any agency.  In terms of its scientific goals and
complexity, it  even  surpassed the Apollo Lunar missions, although not in
cost or operational complexity.  Its success was due to reasonable support
in the early and middle  stages,  to  excellent  management,  and  to  the
dedication of  its  staff,  contractors  and  vendors.  There are numerous
instances in my own experience where I requested assistance from a vendor,
( Prime received many of these ), and tasks that normally took weeks  were
somehow accomplished  in  hours  or days.  For example, during our upgrade
from a Prime 300 to 400 CPU, we were able to have a  government  ADP  plan
approved within several weeks of submission.

   3.1 Mission design

   The initial mission design consisted of a 90 day nominal mission  using
   two identical  spacecraft  systems.   Each  spacecraft  consisted  of a
   orbiter-lander pair, with the orbiter  providing  imaging  of  surface,
   some science measurements, and high rate communications support for the
   lander during  the  nominal  mission operations phase.  Operations were
   planned around a nominal 90 day  mission  where  one  spacecraft  would
   reach Mars  roughly  a month prior to the other:  both spacecraft would
   operate simultaneously after tne landing.  Early in the mission  design
   review process,  reviewers  from  the Mercury, Gemini, Apollo and other
   projects, favorably commented on the mission design  but  indicated  it
   would not  be  possible  to  operate both spacecraft with the staff and
   facilities available, even though  the  mission  operations  staff  was
   roughly 1,000  full  time individuals.  A plan was developed to operate
   the first Lander for approximately 45 sols, ( a sol is a Martian day of
   24 hours and 37 minutes ) and then to reduce its activity to a  minimum
   while landing and operating the second lander for a similar period.  In
   this manner,  the flight control teams were able to maintain reasonable
   10 to 11 hour work days!

   Launch was scheduled for the summer of 1975, followed by  an  11  month
   cruise to  Mars.  Landing was scheduled for July 4, 1976, summer in the
   northern hemisphere and due to the low temperatures on Mars, the system
   was not required to operate through the winter.

   3.2 Early use of Prime in the Viking Mission

   Since testing by the Viking Meteorology Instrument  System,  VMIS,  was
   inadequate due to the small wind tunnel constructed to simulate Martian
   pressures and  its  CO2  atmosphere,  we  decided to perform additional
   testing at NASA Langley Research Center during the summer of 1975.  The
   original plan was to replace the paper tape punch of the TRW VMIS  test
   set with  a  tape  drive  and  use  it  for the tests.  The proposal to
   accomplish that and associated work was $200,000 and I proposed that we
   develop a test set at UW which could both gather  and  reduce  data  in
   real time.   After  preparation  of a lengthy proposal and an extensive
   evaluation, a Prime 300 was selected during the summer of  1974  to  be
   used for  wind  tunnel  testing  of  the  VMIS.  Hardware interfaces to
   simulate the lander computer were developed, software written  and  the
   system checked  out  between  its  delivery  in  September 1974 and its
   shippment to LRC in June of 1975.  I chose RTOS as an operating system,
   a mistake, since hindsight proved that DOS/VM,  ( later  Primos  III ),
   would have  been  a  better  choice  due  to our low data rates and its
   greater software maturity.

   The system had to function properly, and reliably, from  the  beginning
   of testing  as  some  flight qualified hardware was only made available
   after launch and the  NASA  Transonics  Dynamics  Tunnel  is  generally
   scheduled several  years  in  advance.  The TDT is 16 feet in diamater,
   generates wind  speeds  from  10  MPH  to  transonic  and  can  provide
   pressures from  1%  to  100 %  of  atmospheric.   Another  index of its
   capabilities, is that it is powered by a 20,000 HP  motor  which  draws
   1,000,000 watts  at our lowest testing speeds.  During 1974, a specific
   two week time slot was assigned to us at  no  cost,  in  this  facility
   whose testing  cost  was  $4,000  per  hour.   The cost of the computer
   system was less than 10% of  the  value  of  the  test  time.   Initial
   testing was begun in June 1975 in a facility especially designed for us
   and was  interrupted  so  that we could take part in the launch at Cape
   Kennedy.  After launch, the Flight Spare VMIS was  made  available  for
   testing and  we  moved  to  the  TDT.   Testing  was successful, and as
   expected, we had to upgrade our software while our instruments were  on
   the way  to  Mars.  This was somewhat unusual, since all other software
   were essentially in their final form  for  training  exercises  at  JPL
   between launch  and Mars encounter.  The system was moved back to UW in
   November of 1975.

   Once it was determined that our complex software would have to  undergo
   significant changes, we found that adequate time would not be available
   on the  JPL  Univac  1108  systems  ( an  extra  1108 was installed for
   Viking ) and we studied the possibility of providing support at  UW  on
   the Prime  for  users  at  Martin Marietta, Denver, NCAR, Boulder, TRW,
   Redondo Beach, JPL, Pasadena and UW.  Since it was clear that the  P300
   would be  overloaded,  discussions  were  initiated  with  Prime  as to
   possible solutions.  The architecture of the soon to be completed  P400
   was discussed  with J.  W.  Poduska as well as its probable performance
   and availability.  A  presentation  was  made  to  the  Viking  Project
   management to purchase a 60 mbyte disk drive and the new CPU as soon as
   it became available and to provide the software development facility at
   UW.  The  proposal  was accepted, and we began 24 hour/day operation in
   November of 1975 which continues at the present with the  exception  of
   one week  for  the installation of air conditioning.  In April of 1976,
   we received delivery of Serial # 2 of the P400 CPU's.

   3.3 Mission operations during the Primary Mission

   Mission Operations  at  JPL  became  intensive  after  launch  of   the
   spacecraft.  In  the normal course of events, the VMIS system would not
   be operated more than a few times during  cruise  to  check  its  basic
   functionality and  we  would  have mainly been involved in training for
   Mission Operations.  However,  drift  was  detected  in  the  Lander  2
   temperature system  and  the  system was activated a number of times to
   determine the magnitude and nature of the drift.  Although the cause of
   the drift was not discovered, we developed corrections  for  the  early
   mission measurements.

   In June of 1976, we shipped the system to JPL for  Mission  Operations.
   It arrived  at  8 A.M.  and with the assistance of movers, we installed
   it and were operational by  noon.   The  system  was  mainly  used  for
   science analysis, using a version of our Mission Operations meteorology
   software.  This Mission Operations software was configured to produce a
   meteorology tape,  after some preliminary processing, for use on Prime,
   prior to the more extensive data  reduction  segment  of  the  program.
   When the  first  data  were  relayed  from the lander tape recorder, we
   obtained this tape and produced the first  meteorology  data  from  the
   surface of another planet, Mars, on our system.  Since it was summer in
   the tropics  at our landing site, the wind was light and variable, much
   the same as on earth under similar conditions.

   The project director was James Martin of NASA Langley  Research  Center
   and the  success  of  the  mission  was  due  in  a  large  part to the
   competence and dedication of Jim and his staff.  A number  of  possible
   landing sites had been selected prior to Mars encounter on the basis of
   the previous  Mariner  9  mapping  and  Earth  radar  data.  It was the
   function of the site selection group to choose an acceptable  and  safe
   site from  the  previously  selected  sites.   At least a week in orbit
   around Mars was planned for this activity and it was desired to land on
   July 4,  1976,  the  bicentennial.    However,   engineering   prudence
   sometimes delays plans and desired timelines.  The Viking orbiters were
   capable of  resolving  objects  larger than about 40 meters and, in the
   ideal case, one would use observations  of  roughness  elements  larger
   than this  and  extrapolation  to  estimate  the  chance  of spacecraft
   disturbing boulders.  However, all cases are not ideal and earth  based
   radar data  was  required to supplimented the orbiter images.  Although
   the radar can not measure individual small features, they can  estimate
   the size distribution of boulders, etc in large areas which are smaller
   than can  be  resolved in the images.  The combined data indicated that
   the previously chosen sites were not safe and the Fourth of July passed
   as the search went on.  The search could not go on indefinitely due  to
   due to  the  cost  of maintaining 1,000 of us at Mission Operations and
   due to the fact that the second spacrcraft was rapidly approaching  and
   would have  to  occupy  the  resources of the flight operational staff.
   Another site was selected on the basis of radar and  orbiter  data  and
   landing was  initiated.   Due  to  the  one  way propigation time of 18
   minutes from Mars to Earth, the landing sequence had to  be  automated.
   The entry  and  landing procedure consists of three phases.  First, the
   lander separates from the orbiter and retro rockets cause it  to  enter
   the atmosphere,  protected  by its heat shield.  At about 6,400 meters,
   the heat shield is jettisoned and the parachute is  deployed.   Finally
   at about  1,200  meters,  the  parachute  is  jettisoned  and the retro
   rockets are ignited  with  the  descent  being  under  control  of  the
   lander's Guidance  and  Sequencing  Computer, GCSC, radar altimeter and
   inertial reference unit.  The first landing was completely  successful,
   wittnessed by  many  thousands  of  staff  and  families  at JPL and by
   millions throught the world.

   The second landing proceeded 44 sols later with fewer problems  in  the
   site selection  process.   Although  Lander 1 was to be placed in a low
   activity mode for Lander 2's arrival, we managed to schedule continuous
   meteorological data collection from both landers.  To have both landers
   and orbiters functioning successfully, was the result of  good  design,
   management and  planning.   This  is not to imply that there were not a
   few "cliff hangers" such as  the  Biology  Instrument  and  the  GCSC's
   plated wire  memory, but the final results were more than satisfactory.
   At the end of nominal mission operations, the Prime  system  was  moved
   back to UW in November of 1976.

   3.4 Science

   An idea of the complexity of  the  scientific  instrumentation  can  be
   gained by  considering the experiments.  The major individual ones are:

   1) three biology experiements,

   2) organic analysis,

   3) a gas  chromatograph-mass  spectrometer  serving  both  organic  and
   atmospheric analysis,

   4) stereo black and white and color fascimilie imaging system

   5) seismology

   6) meteorology

   7) other supporting components and experiemnts such as the soil sampler
   arm used to feed the experiments and to determine soil properties.   To
   appreciate the  stringent  engineering requirements, one should also be
   aware that the complete lander operated on an average power of 50 watts
   and had to be sterilized  at  130  degrees  Celsius  for  two  24  hour
   periods.  These  simultaneous  requirements,  mandated  innovative  and
   careful design as well as somewhat higher than normal  development  and
   component  cost.   Another  indication  of  the  success  is  that  the
   proceedings from only two of the special  Viking  conferences  weigh  8
   pounds and  contain  1368  pages:   this is only a small portion of the
   Viking generated research publications.

   As to specific results, the consensus is that no evidence for life  was
   found even  though  the  biology  experiments  reacted  in  a  strongly
   positive way.  The reason for the reaction is  that  the  Martian  sols
   contain compounds that liberate oxygen in the presence of water.

   The atmosphere is composed of 95% CO2, small amounts  of  nitrogen  and
   oxygen, as  well  as traces of Argon, hydrogen and other gases.  In the
   field of meteorology, we found that fronts on Mars were more similar to
   those on Earth than we expected.  However, in one instance at Lander 2,
   ( Lander 1 was at 22 degrees north while Lander 2  was  at  48  degrees
   north ) six  or  seven  fronts  passed  by  at  almost  identical  time
   intervals and strengths, as measured from the pressure data:  on earth,
   we rarely  see  such  regularity.   Since  we  were  able  to  continue
   operation for  more  than  three Martian years, we were able to observe
   year to year similarities in many meteorological phenomena as  well  as
   differences.  Major atmospheric, and over long time scales, geological,
   process are  the  global  dust  storms which decrease the daily average
   temperature on the order of 14  degrees  Celsius  or  approximately  25
   degrees Farenheight.   As  the  dust remains in the atmosphere for many
   tens of sols, the effect  is  similar  to  that  discussed  in  Nuclear
   Winter:  Global  Consequences  of  Multiple  Nuclear  Explosions,  R.P.
   Turco, O.B.  Toon,  T.P.   Ackerman,  J.B.   Pollack  and  Carl  Sagan,
   Science, 23 dec.  1983, pp 1283-1292.

   An interesting, and as  yet  unexplained  characteristic  of  the  dust
   storms, is  that some years have major storms while others do not.  For
   example, Year 1 had two, years two and three had none and the beginning
   of year four had one.  We do not know about the rest of year  four  due
   to the landers' failure during this fourth year storm, the most intense
   observed from  the  surface  of  Mars.   Another unusual feature is the
   discovery of transient dust storms, which seem to repeat  at  the  same
   time of  year,  and  which indicate a mode of global oscillation in the
   atmosphere of Mars.

   Many other interesting, and important, atmospheric processes have  been
   studied on  Mars.   One is the year to year similarity in the formation
   and sublimation of Mar's polar caps.  Mars  has  an  inclined  axis  of
   rotation of  25  degrees  celsius,  similar to Earths, which produces a
   large annual temperature range.  Due to its low temperatures and carbon
   dioxide atmosphere, around 20% of the atmosphere condenses, in the form
   of "dry ice" each year with  surprisingly  precise  repeatability  each
   year despite the variation in dust storm intensity and number from year
   to year.   A  difference  is  the  erosion  of  soil from year to year.
   During the third year, between sols 1720 and 1756, ( there are 669 sols
   per Martian year ) piles of dust placed by the soil  sampler  moved  as
   well as  small  pebbles.  These were probably accompanied by local dust
   storms but why did they not move in previous years and why was there no
   global dust storm this year?  We hope that analysis of the data that we
   presently have will  provide  some  insight  into  these  questions  in
   addition to nomerical modelling of the processes.

   Martian meteorology is important, as well as interesting, in  that  its
   atmosphere resembles  that  of Earth more closely than any of the other
   planets, or moons, in our solar  system  which  have  atmospheres.   By
   testing our physical and numeric models of atmospheric motion, climate,
   etc.  on  Martian  observations  as  well  as  terrestrial ones, we can
   refine them to better explain and predict the  effects  of  changes  or
   differences in  the  variable  parameters.   For example, the effect of
   major amounts of  dust  on  the  atmosphere  are  sometimes  easier  to
   understand   Mars,  than  on  Earth,  since  it   swamps   the    other
   meteorological variables at times.  However, there are no funds if FY85
   for Mars Data analysis!

4 Real time operations at the Viking Computer Facility

One of the main problems with the Viking Mission was its  success!   Prior
to landing, I suspect that most of us would readily have traded the chance
of a multi-year mission for a guranteed 90 day mission without hesitation.
It the  end  of  the  nominal  mission  we  were  faced  with four healthy
spacecraft and an excellent flight operations team.  During the next  year
or so,  we  at  UW  were  content  to  continue receiving data from JPL in
processed science form even though we had operational software  to  obtain
meteorology data  from  the  meteorology  Front  End Processor, FEP, tapes
produced by the JPL UNIVAC 1108 system.  However, if we were to be able to
obtain meteorology data in the future, it was clear that we would have  to
implement   some  of  the  operational  software  which  handled  the  raw
spacecraft data stream from the Deep Space Network, DSN, since the  filght
operations IBM 360/75's were certain to be decommissioned soon.  A minimal
set of  this  software  was  implemented  on  the  VCF's  Prime for use in
obtaining meteorology results from the meteorology science data format  in
the raw  data stream and pressure from the engineering data format.  While
implementing this capability, changes were made in  the  data  format  and
block lengths by NASA, which we included as options.  In Janurary of 1981,
we began  processing data on a weekly basis, including a comprehensive set
of engineering parameters for the  operations  team  at  JPL.   Data  were
provided to  JPL by dial up access or by mail.  In the next few months, we
expanded the engineering processing, including plotting selected, and then
all, engineering parameters.  Prior to our  conversion  of  the  software,
data were plotted by hand at JPL if at all.

Around that time, it became  clear  that  the  lander  might  continue  to
function for  many  years  and  dedicated, part time, Viking staff members
initiated a program to recondition the two dead  nickel-cadmium  batteries
of the  four  on Lander 1.  To assist in the rapid turnaround required for
this effort to be successful, I proposed that we implement a direct,  real
time link  between  JPL  and the VCF since the previous method was to mail
tapes from JPL to UW.  This was acepted and after several iterations,  the
communications configuration  of  Figure 3-8,  Telecommunications and Data
Acquisition System Support for the Viking 1975 Mission to Mars, The Viking
Lander Monitor  Mission  May  1980  to  March  1983,  D. G. Mudgway,   JPL
publication 82-107   was implemented.  The synchronous NASA communications
codes were decoded and input to an AMLC port on the  VCF  using  an  Intel
system.  First  testing of the system was accomplished on May 14, 1982 and
our permanent installation was implemented in October of 1982.   The  only
special provisions  made on the Prime end were to increase the size of the
AMLC buffer to around 1,000 bytes to preclude the  possibility  of  buffer
overflow.  Since  the  data  rate  from  Mars to Earth was 1,000 bits/sec,
there was no need to assign a high priority to this task.  With  our  real
time capability, we were able to provide immediate analysis of the battery
conditioning results  for  planning  the  following  sequences in a timely

5 Development of the Smithsonian National Air and Space Exhibit

Prior to the establishment of the real time link, we had  been  displaying
lander images  on our AED 512 image processor.  Once the plainning for the
link was initiated, Dr Farouk El-Baz of the Smithsonian National  Air  and
Space Museum  was  consulted as to whether the Museum would like to have a
weekly picture "Live from Mars", provided we could obtain the donation  of
an image  processor.   After  a  comittment  of  AED  to  donate  an image
processor I requested that Prime donate a  used  system  for  the  Museum.
After long  negotiatious  with  the  varions parties, and Stan Kent of the
Viking Fund providing maintenance funds, a system  was  donated  including
two   Prime  microcoded  MPC  4  controllers,  to  allow  high  speed  DMA
communications between Prime and the image processor.

Microcode for the MPC 4 was written by  Noel  Cheney  of  the  Atmospheric
Sciences Department at UW, while we continued to operate 24 hours/day.  To
minimize impact  to  users  and  disruption of our continuous weather data
collection and processing, initially the testing of MPC  4  microcode  was
done between 7 and 8:30 AM.  To make the development of this code opssible
under such  constraints, Dr.  Harold Edmon of the VCF wrote a debugger for
microcode development as well as a routine to download  microcode  without
cold or warm starting the system.  User interfaces for the MPC 4 and image
processing software were written by James Synge of the VCF.  William Guest
processed and  generated the meteorology graphics that are included in the
display and Neal Johnson provided in Viking data processing.  The sequence
of text, graphics and images  that  are  presented  at  the  Museum,  were
developed by Dr.  Ted Maxwell of the museum, and myself and I designed the
overall system  as well as convincing the interested parties to donate the
required resources.

Subsequent to our development  of  the  display,  which  requires  only  a
special cable  and  our  microcode  to drive the AED, we have developed an
expansion capability which permitts multiple AED's to  be  driven  by  one
port with  a  small  interface box, which supports up to three local image
processors and provides line drivers to another  similar  interface.   The
next interface  can  be  located  thouands  of  feet  away and in turn can
support several image processors.  While this does violate our "commercial
hardware only" policy it does allow high speed and significant flexibility
with minimal additional hardware.  I  hope  that  such  features  will  be
provided as off the shelf items in the near furure by Prime or others.

Unfortunately, schedules and other complications delayed  the  opening  of
the exhibit  until  after  our loss of the lander.  However, during one of
our routine real time downlinks from Mars, we  processed  and  transmitted
the weekly  image to the Smithsonian system via Primenet within an hour of
receipt of the data by  our  facility  as  a  simple  demonstration  which
required no  software  changes  on  our part.  Primenet was routinely used
between NASM and UW during our joint  development  and  debugging  of  the

While the loss of the "Live from Mars" aspect, lessens
the excitement, the display was never planned to include more than a
small amount of the latest data, due to the once a week transmission.
Also, the fact that the data are transmitted at Mars noon coupled with
the 37 minute difference in day length, gurantee that the majority of
the downlinks would not have been live during public hours.  I would
reccommend that you take advantage of the opportunity to view the
exhibit, at the Museum due to the other historical items associated
with the display and during this meeting.  In the Smithsonian, it is a
permanent exhibit buried upstairs in the "Exploring the Planets"
gallery, which requires dilligence to find.



The Viking Mission to Mars was  the  most  sophisticated  and  interesting
planetary missions  ever  executed.  The enclosed table summarizes some of
the operational parameters and it should be remembered  that  the  landers
both lasted  through  winters with temperaures of -118 degrees Celsius and
Lander 1, the Thomas Mutch Memorial Station, lasted 2,245 sols, roughly 20
times its design life.  Such  performance  is  a  proper  tribute  to  the
spacecraft designers and operators, as well as the Project management!  As
a follow  on,  I  suggest  that  we begin planning for a manned mission to
Mars, inviting and encouraging all nations to take part. 

Figure 1

Viking Lander "As Built" Performance Capabilities. NAS1-9000, June 1976. Martin Marietta Corp., Denver Division, Denvery, CO 80201

Figure 2 Mission Operations Communications including Real Time. NASA Deep Space Network >> Jet Propulsion Laboratory >> University of Washington >> Smithsonian National Air & Space Museum, Washington DC. From "Telecommunications and Data Acquisition System Support for the Viking 1975 Mission to Mars, The Viking Lander Monitor Mission May 1980 to March 1983", D. G. Mudgway, JPL publication 82-107. ______________________________________________________________________ ______________________________________________________________________ Parameter V0-1 V0-2 ______________________________________________________________________ Number of days from launch to end of mission 1813.98 1049.52 Number of orbits of Mars 1488.0 706.1 Number of pictures recorded in orbit 36,622 16,041 BILLION data bits played back from 357.7 161.3 the tape recorders (including lander relay data) Tape travel across recorder heads, km 2955 1397 Number of commands sent by the Network 269,500 Number of tracking passes supported by the Network 7,380 Hours of tracking time provided by the Network, 56,500 _________________________________ Table 1. General Viking Orbiter Statistics ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ Event Viking 1 Viking 2 ______________________________________________________________________ Launch Aug. 20, 1975 Sept. 9, 1975 Arrival June 19, 1976 Aug. 7, 1976 Landing July 20, 1976 Sept. 3, 1976 Site Chryse Planitia Utopia Planitia Coordinates 22.3 N, 48.0 47.7 N, 225.8 Orbiter in orbit 1,509.9 days 718.8 days Lander active on surface 2,245 days 1,316.1 days End lander operations Nov. 13, 1982 April 11, 1980 End orbiter operations Aug. 7, 1980 July 25, 1978 Orbiter photos 51,539 Lander photos More than 4,500 Photo coverage 97% of planet with resolution of 300 m (1,000 ft) or better. 25% of planet with resolution of 25 m (82 ft) or better. Lander weather reports: more than 1 million Orbiter infrared observations: more than 1 million Orbiter weight: 2,325 kg Lander weight: 571 kg Orbiters built by Jet Propulsion Laboratory Lander built by Martin Marietta Aerospace Project managed by NASA Langley Research Center ____________________ TABLE 2 ______________________________________________________________________ ______________________________________________________________________

J. Tillman: