Viking 2 Orbiter
Launch Date Sept. 9, 1975
Launch Site Cape Canaveral, Florida, USA
Destination Mars
Type Orbiter
Status Successful
Nation United States
Alternate Names 1975-083A, Viking Orbiter 2, Viking-A Orbiter, 08199


NASA's Viking mission to Mars was composed of two pairs of spacecraft—Viking 1 and Viking 2 —each consisting of an orbiter and a lander. The spacecraft were designed to take high-resolution images of the Martian surface, characterize the structure and composition of the atmosphere and surface, and search for evidence of life.


Viking 2 lander set down on Utopia Planitia and operated until April 1980. The four Viking spacecraft provided numerous new insights into the nature and history of Mars, producing a vivid overall picture of a cold weathered surface with reddish volcanic soil under a thin, dry carbon dioxide atmosphere, clear evidence for the existence of ancient river beds and vast floods, and no detectable seismic activity.

Although no traces of life were found, Viking found all elements essential to life on Earth—carbon, nitrogen, hydrogen, oxygen and phosphorus—were present on Mars.

Key Dates

Sept. 9, 1975: Launch

Aug. 7, 1976: Mars Orbit Insertion

Sept. 3, 1976 | 22:58:20 UT: Mars Landing

Apr. 11, 1980: End of Mission

In Depth

Viking-A was scheduled to launch before Viking-B, but had to launch second due to a problem with its batteries that had to be repaired.

After a successful launch and a midcourse correction on 19 September 1975, Viking 2 entered orbit around Mars on 7 August 1976, nearly a year after launch.

As with Viking 1, photographs of the original landing site indicated rough terrain, prompting mission planners to select a different site at Utopia Planitia near the edge of the polar ice cap where water was located, that is, where there was a better chance of finding signs of life.

The lander separated from the orbiter without incident on 3 September 1976 and, after atmospheric entry, landed safely at 22:37:50 UT about 6,460 kilometers from the Viking 1 landing site. Touchdown coordinates were 47.968 degrees north latitude and 225.71 degrees west longitude

Viking 2 lander image of Mars
The boulder-strewn field of red rocks reaches to the horizon nearly two miles from Viking 2 on Mars' Utopian Plain. Image Credit: NASA

Photographs of the area showed a rockier, flatter site than that of Viking 1. The lander was in fact tilted 8.5 degrees to the west. The biology experiments with scooped-up soil produced similar results to that of its twin -- inconclusive on the question of whether life exists or ever has existed on the surface of Mars. Scientists believed that Martian soil contained reactants created by ultraviolet bombardment of the soil that could produce characteristics of organisms living in Earth soil.

The orbiter continued its successful imaging mission, approaching as close as 28 km to the Martian moon Deimos in May 1977. A series of leaks prompted the termination of orbiter 2 operations on 24 July 1978, while lander 2 continued to transmit data until 12 April 1980. In total, the two orbiters returned 51,539 images of Mars at 300 meters resolution, that is, about 97 percent of the surface. The landers returned 4,500 photos of the two landing sites.


Launch Vehicle: Titan IIIE-Centaur

Spacecraft Mass:

Orbiter: 2,339 kilograms

Lander: 978 kilograms

Spacecraft Instruments


  1. imaging system
  2. atmospheric water detector
  3. infrared thermal mapper


  1. imaging system
  2. gas chromatograph mass spectrometer
  3. seismometer
  4. x-ray fluorescence
  5. biological laboratory
  6. weather instrument package (temperature, pressure, wind velocity)
  7. remote sampler arm


  1. retarding potential analyzer
  2. upper-atmosphere mass spectrometer

Additional Resources

National Space Science Data Center Master Catalog: Viking 1 Orbiter

National Space Science Data Center Master Catalog: Viking 1 Lander

National Space Science Data Center Master Catalog: Viking 2 Orbiter

National Space Science Data Center Master Catalog: Viking 2 Lander

Selected References

Siddiqi, Asif A. Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000, NASA, 2002.

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