Viking Project: mission and targets

Project start

August 20, 1975

Declared end

May 21, 1983

The start the archive declares is the start of the project, not the launch, and an end it does not declare does not mean the mission is still running.

Targets you can open in 3D:

• Mars
• Deimos
• Phobos
• Sun

A declared target is what the archive files the mission’s data under, not a record of observation.

The Viking mission to Mars consisted of four spacecraft: the two orbiters VO1 and VO2, and two landers VL1 and VL2. During cruise to Mars, the landers were attached to the orbiters; the combined spacecraft were then known as Viking 1 and 2. The role of the orbiters was to transport the landers to Mars, to carry reconnaissance instruments for certifying the landing sites, to act as relay stations for lander data, and to perform their own scientific investigations. The initial orbit periapses were placed over the candidate landing sites to allow for maximum viewing resolution and relay of the lander data. After the primary lander missions were completed, the orbiters' orbits were allowed to drift so that the entire planetary surface could be systematically mapped by the three remote sensing experiments. The Viking 1 spacecraft was launched August 20, 1975, and arrived at Mars on June 19, 1976. Lander 1 was deployed to the Mars surface on July 20, 1976. The VO1 orbital inclination of 38-39 degrees was chosen to optimize communication with VL1. Viking 2 was launched September 9, 1975 and arrived at Mars August 7, 1976. VL2 landed on September 3, 1976, at a more northerly site than VL1. The VO2 orbit was correspondingly more inclined than VO1; initially 55 degrees, it was later adjusted to 80 degrees, providing particularly good coverage of polar regions. The areocentric locations of VL1 and VL2 have since been determined to be (22.270N, 48.264W) and (47.669N, 226.032W), respectively.

Quoted in English, as the archive publishes it, read on October 4, 2026.

Identifier in the archive, which is its citation: urn:nasa:pds:context:investigation:mission.viking

NASA Planetary Data System, PDS Registry, investigation context products. Dates and targets read on September 29, 2026; how to cite the archive: https://pds.nasa.gov/datastandards/citing/

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