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— CH. 1 · MISSION GENESIS AND LAUNCH —

Viking program

~4 min read · Ch. 1 of 7
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  • The Viking program began its life in 1968 when NASA Langley Research Center took charge of the effort. This initiative grew from an earlier, even more ambitious Voyager Mars program that never flew to the Red Planet. The first craft, Viking 1, lifted off on the 20th of August 1975, riding atop a Titan IIIE rocket with a Centaur upper stage. A second identical probe followed just weeks later on the 9th of September 1975. Both spacecraft were designed as pairs consisting of an orbiter and a lander. The orbiters would photograph the Martian surface while acting as communication relays for their lander counterparts once they touched down.

  • Each orbiter measured approximately 3 meters across and weighed roughly 4,000 kilograms fully fueled. Eight solar panel wings extended from the central axis, creating a total span of about 14 meters from tip to tip. These panels contained 34,800 individual solar cells capable of generating 620 watts of power at Mars distance. Two nickel-cadmium batteries stored energy for periods when the spacecraft did not face the Sun directly. Propulsion relied on a bipropellant liquid-fueled engine using monomethylhydrazine and nitrogen tetroxide. This main unit could gimbal up to 9 degrees to steer the vehicle during orbital maneuvers. Twelve small compressed-nitrogen jets handled attitude control adjustments throughout the mission duration.

  • Viking 1 touched down on the 20th of July 1976, more than two weeks before its twin arrived in orbit. The descent sequence began with a deorbit burn that separated the lander from its parent orbiter. Atmospheric entry generated peak heating just seconds after frictional contact with the thin Martian atmosphere. At an altitude of about 15 kilometers, a parachute deployed while traveling at 900 kilometers per hour. The aeroshell released itself as the legs unfolded near 1.5 kilometers above ground level. Three retro-engines fired immediately to slow the craft for a soft landing. Viking 2 followed this exact procedure and successfully landed on the 3rd of September 1976. Each lander weighed approximately 600 kilograms upon final touchdown after burning through its propellant reserves.

  • The landers carried instruments designed to study biology, chemistry, meteorology, and seismology. Two 360-degree cylindrical scan cameras mounted near one side of the base captured images using movable mirrors. A sampler arm extended from the center equipped with a collector head, temperature sensor, and magnet. A meteorology boom held sensors for wind direction and velocity extending upward from a leg. An interior compartment housed the biology experiment alongside a gas chromatograph mass spectrometer. The total scientific payload weighed roughly 40 kilograms. Communications relied on a 20-watt S-band transmitter paired with two traveling-wave tubes. Data storage occurred on a 40-Mbit tape recorder within the lander computer system.

  • Orbiter imagery revealed huge river valleys carved by massive floods across many areas of Mars. These features showed water breaking through dams and eroding grooves into bedrock over thousands of kilometers. Branched stream networks in the southern hemisphere suggested that rain once fell on the planet. Some volcano flanks resembled those formed by rainfall on Hawaiian volcanoes. Craters appeared as if impactors had fallen into mud rather than dry rock. Ice melting in the soil turned ground into fluid that flowed around obstacles during formation events. Regions called Chaotic Terrain lost great volumes of water quickly, creating large channels. Estimates placed the water involved at ten thousand times the flow of the Mississippi River.

  • One biological experiment returned positive results indicating current metabolism in Martian soil samples. Two other experiments failed to reveal any organic molecules within the same soil. Most scientists concluded these conflicting signals resulted from non-biological chemical reactions caused by highly oxidizing conditions. The validity of the Labeled Release test hinged entirely on the absence of an oxidative agent. Later discoveries by the Phoenix lander identified perchlorate salts as the missing factor. Perchlorates destroy organics when heated and produce chloromethane and dichloromethane compounds found by Viking. Researchers proposed that organic compounds could have existed but remained unnoticed due to this chemical interference. An international team reported studies in 2012 suggesting extant microbial life might be present based on complexity analysis.

  • NASA spent roughly one billion dollars on the entire program at the time of launch. Development costs for the lander design alone reached 357 million dollars. The most expensive single component was the life-detection unit costing about 60 million dollars. The camera system required 27.3 million dollars to develop despite manufacturing challenges. Program managers faced pressure to simplify imaging systems but maintained their advanced design choices. The mission operated until the 21st of May 1983 when all craft eventually failed or shut down. Viking 1 orbiter fuel depletion ended operations after four years while the lander survived until November 1982. Human error during a software update caused the final communication loss for the lander. Modern Mars Reconnaissance Orbiter located the Viking 1 lander site six kilometers from its intended target in December 2006.

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Common questions

When did the Viking program begin and what was its origin?

The Viking program began in 1968 when NASA Langley Research Center took charge of the effort. This initiative grew from an earlier Voyager Mars program that never flew to the Red Planet.

What were the launch dates for Viking 1 and Viking 2 spacecraft?

Viking 1 lifted off on the 20th of August 1975 while a second identical probe followed on the 9th of September 1975. Both spacecraft were designed as pairs consisting of an orbiter and a lander.

How much power could the solar panels generate at Mars distance?

The eight solar panel wings contained 34,800 individual solar cells capable of generating 620 watts of power at Mars distance. Two nickel-cadmium batteries stored energy for periods when the spacecraft did not face the Sun directly.

On which dates did Viking 1 and Viking 2 touch down on Mars?

Viking 1 touched down on the 20th of July 1976 and Viking 2 successfully landed on the 3rd of September 1976. Each lander weighed approximately 600 kilograms upon final touchdown after burning through its propellant reserves.

What scientific instruments did the Viking landers carry to study Mars?

The landers carried two 360-degree cylindrical scan cameras, a sampler arm with a collector head, and a meteorology boom holding sensors for wind direction. An interior compartment housed the biology experiment alongside a gas chromatograph mass spectrometer.

When did the Viking program operations end and what caused the final communication loss?

Mission operations ended on the 21st of May 1983 when all craft eventually failed or shut down. Human error during a software update caused the final communication loss for the lander.

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All sources

35 references cited across the entry

  1. 1webViking 1Jon Nelson — JPL
  2. 2webViking 2Jon Nelson — JPL
  3. 3webViking Mission to MarsDavid R. Dr. Williams — NASA — December 18, 2006
  4. 4newsViking 1: First U.S. Lander on MarsElizabeth Howell — October 26, 2012
  5. 5webThe Viking ProgramThe Center for Planetary Science
  6. 6webViking LanderCalifornia Science Center — July 3, 2014
  7. 7webViking Fact SheetJet Propulsion Laboratory
  8. 8bookMarsUniversity of Arizona Press — 1992
  9. 9bookMars: Uncovering the Secrets of the Red PlanetPaul Raeburn — National Geographic Society — 1998
  10. 10bookThe Atlas of the Solar SystemPatrick Moore et al. — Mitchell Beazley — 1990
  11. 11bookMapping Mars: Science, Imagination, and the Birth of a WorldOliver Morton — Picador — 2002
  12. 12magazineAmazing Search for Life On MarsHearst Magazines — Hearst Magazines — June 1976
  13. 13journalThe First Viking Mission to MarsG. A. Soffen et al. — August 27, 1976
  14. 14encyclopediaCarl SaganHelge Kragh
  15. 15webViking
  16. 16webSNAP-19 Radioisotope Thermoelectric Generator Fact Sheet by Energy Research & Development Administration (ERDA) Diagram 2 - The Energy Research and Development Administration
  17. 17journalA Concept for NASA's Mars 2016 Astrobiology Field LaboratoryLUTHER W. BEEGLE — August 2007
  18. 18webPerchlorate found in Martian soilJohn Johnson — August 6, 2008
  19. 19newsMartian Life Or Not? NASA's Phoenix Team Analyzes ResultsAugust 6, 2008
  20. 20newsReanalysis of the Viking results suggests perchlorate and organics at midlatitudes on MarsRafael Navarro–Gonzáles — December 15, 2010
  21. 21magazineLife on Mars Found by NASA's Viking MissionKer Than — April 15, 2012
  22. 22journalComplexity Analysis of the Viking Labeled Release ExperimentsGiorgio Bianciardi et al. — March 2012
  23. 23webMars Viking Robots 'Found Life'Irene Klotz — DiscoveryNews — April 12, 2012
  24. 24journalIdentification of Chlorobenzene in the Viking Gas Chromatograph-Mass Spectrometer Data Sets: Reanalysis of Viking Mission Data Consistent With Aromatic Organic Compounds on MarsMelissa Guzman et al. — 2018
  25. 25webPDS: Instrument Information
  26. 26bookThe Martian LandscapeThe Viking Lander Imaging Team — NASA — 1978
  27. 27newsViking Cameras Light in Weight, Use Little Power, Work SlowlyVictor K. McElheny — July 21, 1976
  28. 28webMars Lander Retro Propulsion (IAF-99-S.2.02)
  29. 29tech reportComputers in Spaceflight: The NASA ExperienceJames Tomayko — NASA — March 1988
  30. 30webNASA Reference Publication 1027: Viking '75 spacecraft design and test summary. Volume 1 – Lander designNeil A. Holmberg — NASA — November 1980
  31. 31webNASA Reference Publication 1027: Viking '75 spacecraft design and test summary. Volume 2 – Orbiter designNeil A. Holmberg — NASA — November 1980
  32. 32bookFaster, Better, Cheaper: Low-Cost Innovation in the U.S. Space ProgramHoward E. McCurdy — JHU Press — 2001
  33. 33webViking 1 Orbiter spacecraft detailsNASA — March 20, 2019
  34. 34magazineProbe's powerful camera spots Vikings on MarsDavid Chandler — December 5, 2006
  35. 35webVisions of Mars: Then and Now