Either of two US space probes to the planet Mars, each one consisting of an orbiter and a lander. They were launched on 20 August and 9 September 1975, and transmitted colour pictures and analysed the planet's soil.
Viking 1 carried life-detection laboratories and touched down on 20 July 1976 in the Chryse lowland area. Designed to work for 90 days, the craft operated for 6.5 years, losing contact with Earth in November 1982. No definite signs of life were found.
Viking 2 landed in Utopia on 3 September 1976 and functioned for 3.5 years.
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