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Observation of Mars has been ongoing since the ancients noted its existence and its movements. The invention of the telescope provoked the first serious study of Mars as a celestial object, and not a prophetic sign. Yet not all of this observation led to proper inferences. Percival Lowell's canal theory would lead to more than half a century of vain speculation on extraterrestrial civilization before the first successful exploratory missions would return evidence forcing the abandonment of that theory.

Observation of Mars has been ongoing since the ancients noted its existence and its movements. The invention of the telescope provoked the first serious study of Mars as a celestial object, and not a prophetic sign. Yet not all of this observation led to proper inferences. Percival Lowell's canal theory would lead to more than half a century of vain speculation on extraterrestrial civilization before the first successful exploratory missions would return evidence forcing the abandonment of that theory.

Mars has been the subject of more attempt to explore it, and more failures, than any other planet. Of approximately 37 separate missions to Mars, only 13 have had any success. The planetary scientists of the [[Union of Soviet Socialist Republics]], so successful in exploring [[Venus]], experienced ten mission failures before achieving their first success, seven years after the [[United States]] achieved success with its [[Mariner 4]] mission. That Soviet mission, [[Mars 3]] in 1971, succeeded in placing a lander on Mars, but the lander's system transmitted for only 20 seconds before failing.

Mars has been the subject of more attempts to explore it, and more failures, than any other planet. Of approximately 37 separate missions to Mars, only 13 have had any success. The planetary scientists of the [[Union of Soviet Socialist Republics]], so successful in exploring [[Venus]], experienced ten mission failures before achieving their first success, seven years after the [[United States]] achieved success with its [[Mariner 4]] mission. That Soviet mission, [[Mars 3]] in 1971, succeeded in placing a lander on Mars, but the lander's system transmitted for only 20 seconds before failing.

In 1975, [[Project Viking]] achieved the most notable success by placing two orbiters and two landers on Mars. Neither nation would attempt any further missions to Mars until 1988, when the Soviets lost one craft en route and lost contact with the other ([[Phobos 2]] seconds after its rendezvous with Mars's inner [[moon]] [[Phobos]]. Nor was the United States' program immune to failure; its ''Mars Observer'' vessel was lost prior to arrival after some propulsion systems failed.<ref name=faq/>

In 1975, [[Project Viking]] achieved the most notable success by placing two orbiters and two landers on Mars. Neither nation would attempt any further missions to Mars until 1988, when the Soviets lost one craft en route and lost contact with the other ([[Phobos 2]] seconds after its rendezvous with Mars's inner [[moon]] [[Phobos]]. Nor was the United States' program immune to failure; its ''Mars Observer'' vessel was lost prior to arrival after some propulsion systems failed.<ref name=faq/>