Viking 1 launched aboard a Tital IIIE rocket August 20, 1975 and arrived at Mars on June 19, 1976. The first month was spent in orbit around the martian planet and on July 20, 1976 Viking Lander 1 separated from the Orbiter and touched down at Chryse Planitia. Image Credit: NASA.

Launch Date Aug. 20, 1975
Launch Site Cape Canaveral, Florida, USA
Destination Mars
Type Orbiter
Status Successful
Nation United States
Alternate Names 1975-075A, Viking-B Orbiter, Viking Orbiter 1, 08108


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 1 was the first successful mission to land on Mars (the Soviet Mars 3 lander survived for a few seconds after landing in 1971, but sent back no science data). The Viking 1 lander operated on Chryse Planitia until November 1982. 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

Aug. 20, 1975: Launch

19 June 1976: Mars Orbit Insertion

July 20, 1976 | 1:53:06 UT: Mars Landing

Feb. 1, 1983: End of Mission

In Depth

Viking 1 was the first of a pair of complex deep space probes that were designed to reach Mars and collect evidence on the possibility (or lack thereof) for life on Mars.

Each spacecraft was composed of two primary elements, an orbiter (2,339 kilograms) and a lander (978 kilograms). The orbiter design heavily borrowed from the Mariner buses, while the lander looked superficially like a much larger version of the Surveyor lunar lander.

Prior to launch, the batteries of the first spacecraft were discharged, prompting NASA to replace the original first spacecraft with the second, which was launched as Viking 1.

After three midcourse corrections (on 27 August 1975 and 10 and 15 June 1976), the spacecraft entered orbit around Mars on 19 June 1976. Initial orbital parameters were 1,500 x 50,300 kilometers. The following day, when the orbiter began transmitting back photos of the primary landing site in the Chryse region, scientists discovered that the area was rougher than expected.

First Photo of Mars
The first photo ever taken of the surface of Mars. Viking 1’s footpad is visible on the right. Image Credit: NASA

Using the new photos, scientists targeted the lander to a different site on the western slopes of Chryse Planitia. The lander separated from the orbiter, and after a complex atmospheric entry sequence, during which the probe took air samples, Viking 1 lander set down safely at 22.483 degrees north latitude and 47.94 degrees west longitude at 11:53:06 UT on 20 July 1976.

Once down, the spacecraft began taking high quality photographs (in three colors) of its surroundings. Instruments recorded temperatures ranging from -86 degrees Celsius (before dawn) to -33 degrees Celsius (in the afternoon). The seismometer on the lander was inoperable.

On 28 July, the lander's robot arm scooped up the first soil samples and deposited them into a special biological laboratory that included a gas chromatograph mass spectrometer. While some data could be construed as indicating the presence of life, a major test for organic compounds gave negative Results.

The lander continued to return daily (and then eventually weekly) weather reports until loss of contact on 1 February 1983. Further attempts to regain contact proved unsuccessful. The orbiter was shut down on 7 August 1980, after it ran out of attitude-control propellant.


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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