What was the first artificial satellite to orbit Mars?

Mariner 9 was the first artificial satellite to orbit Mars.

NASA’s Mariner 9 entered Mars orbit on November 13, 1971. It became the first spacecraft to orbit another planet, completing a major step beyond earlier flyby missions. Its cameras mapped much of Mars while a planet-wide dust storm initially obscured the surface.

As the storm cleared, Mariner 9 revealed volcanoes, channels, canyons, and other features that transformed scientific understanding of Mars. It discovered the enormous canyon system later called Valles Marineris and photographed the planet’s two small moons in detail.

Mariner 4 had already returned the first close-up pictures during a 1965 flyby, but it never entered orbit. Mars 2 and Mars 3 arrived in the same general period, yet they were Soviet missions with different outcomes. Mariner 9’s achievement was specifically orbital insertion.