Technically they were not the first to do so: in 1971 the USSR’s Mars 3 mission’s lander reached the surface. Related: Elon Musk planning SpaceX mission to Mars by 2018Of those 18 missions, just half were fully successful. All but one of them were launched by the US, the exception being India’s successful Mars Orbiter mission, which arrived in September 2014 and continues to operate. It achieved orbit two weeks before the first USSR orbiter, Mars 2, reached its destination. The ESA’s Mars Express, which achieved orbit in 2003, has imaged 95% of the surface of the planet and taken various measurements, hugely expanding our knowledge.

Source: The Guardian July 23, 2016 06:56 UTC