Launch of Mariner 9

Mariner 9 was a NASA spacecraft that became the first to orbit another planet when it reached Mars in November 1971. It was launched a few weeks after the loss of its twin, Mariner 8, and arrived to find the planet wrapped in a global dust storm that hid the surface. After waiting for the dust to clear, it mapped most of the planet and sent back thousands of images. They revealed giant volcanoes, including Olympus Mons, a huge canyon system later named Valles Marineris, and channels that looked as if they had been carved by flowing water. Mariner 9 also gave the first detailed views of the moons Phobos and Deimos.

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