The Viking Project was formally begun by NASA on November 15, 1968 and was composed of two orbiters and two landers. The originally planned launch opportunity was 1973 but this was later slipped to 1975 as the complexity and challenge of the project became increasingly clear. The project had been many years in planning and had as its principal goal a direct determination of whether extant life existed in the red soil of the planet. The preceeding Mariner 1971 mission (Mariner 9) was to serve as its pathfinder.
The Viking mission was a spectacular technological and scientific success -- data from the mission, especially the orbiters, have been intensively analysed ever since by an enthusiastic science community. We realise, however, that the specific life detection experiments carried out by the landers were somewhat premature and that we need to map the planet and choose our future landing sites more systematically than was possible twenty years ago.
Viking 1 Viking 2
Launch Site Kennedy Space Center Kennedy Space Center
Launch date 08/20/1975 06/09/1975
Insertion into martian orbit 06/19/1976 08/07/1975
Orbit type apoapsis 33.000 km Inclined on the
periapsis 1513 km equatorial plan
a)Orbit modified 02/12/77 Orbit modified
to image Phobos to image Deimos
b) Orbit modified 03/17/77
to survey Mars at 300 km
Landing date 07/20/1976 09/03/1976
Landing Site Chryse Planitia Utopia Planitia
End of Mission November 1982 August 1980
Some numbers: Viking missions: 50.000 orbital images; 3000 surface panoramas; thousands of physico-chemical data; hundreds of derived geologic, topographic, photomosaic, and shadow maps.
Experiences Instruments
Orbital Imagery 2 Vidicon Cameras Atmospheric H20 mapping Infrared spectrometer Thermal mapping Infrared radiometer Ionospheric properties Analyser Atmosphere composition Mass spectrometer Atmosphere structure Barometer, thermometer Surface Imagery 2 cameras ITEK Biological analyses 3 separated elements * Metabolism * Growth * Photosynthesis Mineralogic analysis Fluorescence X spectrometer Meteorology Pressure measurements, Temperature and anemometer Sismology Sismometer
Date Revolution Event
June 19, 1976 0 Mars Orbit insertion June 21, 1976 2 Trim to plan site certification orbit July 9, 1976 19 Orbit trim to move westward July 14, 1976 24 Synchronous orbit over landing site July 20, 1976 30 VL-1 landing at 11:53:06 UTC Aug.3, 1976 43 Minor orbit trim to maintain synchronization over VL-1 Sept.3, 1976 75 VL-2 landing Sept.11, 1976 82 Decrease of orbit period to begin eastward walk Sept 20, 1976 92 Orbit trim to permit synchronization over VL-2 Sept.24, 1976 96 Synchronous orbit over VL-2 Jan 22, 1977 213 Period change to approach Phobos Feb.4, 1977 227 Orbit synchronization with Phobos period Feb.12, 1977 235 Precise correction to Phobos synchronization March 11. 1977 263 Reduction of periapsis to 300 km March 24, 1977 278 Adjustment of orbit period to 23.5 hours May 15, 1977 331 Small Phobos - avoidance maneuver July 1, 1977 379 Adjustment of orbit period to 24.0 hours Dec. 2, 1978 898 Adjustment of orbit priod to 24.85 hours; beginning slow walk around the planet May 19, 1978 1061 Adjustment of orbit period to 25.0 hours; Acceleration of walk rate July 20, 1979 1120 Raising of periapsis to 357 km; Adjustment of orbit period to 24.8 hours and slowing of walk rate.
Date Revolution Event
Aug. 7, 1976 0 Mars orbit insertion Aug.9, 1976 2 Period and altitude adjustment. Beginning of westward walk Aug.14, 1976 6 Increase of period to increase walk rate Aug.25, 1976 16 Decrease of walk rate to proceed to landing site Aug. 27, 1976 18 Synchronous orbit over landing sit Sept.3, 1976 25 VL-2 landing at 22:27:50 UTC Sept. 30, 1976 51 Change of orbit plane to 75° inclination and beginning of westward walk Dec.20, 1976 123 Lowering of periapsis to 800 km and increasing of inclination to 80° March 2, 1977 189 Synchronous orbit over VL-2 April 18, 1977 235 Period change: 13 revolutions equals 12 Mars days Sept.25, 1977 404 Change of orbit period to approach Deimos Oct.9, 1977 418 Orbit synchronization with Deimos Oct.23, 1977 432 Change of orbit period to 24.0 hours and lowering of periapsis to 300 km July 25, 1978 706 Powered down
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