Mariner 9 became the first spacecraft to orbit another planet

On November 13, 1971, NASA’s Mariner 9 fired its engine and slid into orbit around Mars, becoming the first spacecraft to orbit another planet. It had launched from Earth on May 30, 1971, narrowly beating two Soviet probes to the milestone.

The arrival was an anticlimax. A planet-wide dust storm had swallowed the surface, leaving controllers staring at a featureless orange haze for weeks. Mission planners, having built a craft that could be reprogrammed in flight, simply told it to wait.

When the dust settled, Mars looked nothing like the dead, cratered world earlier flybys had implied. Mariner 9 mapped about 85% of the surface and revealed the Valles Marineris canyon system and the towering volcano Olympus Mons, alongside channels hinting at ancient flowing water.

It operated until October 1972, returning over 7,000 images.

The mission turned Mars from a curiosity into a destination.