Mariner 9 finds new features

[Jopa]

Viewing parts of Mars missed by previous probes, Mariner 9 revealed three huge volcanoes and a massive canyon, now estimated to be 5 miles (8km) deep and over 1,800 miles (3,000km) long. The probe also took photographs of Mars's moons, Phobos and Deimos.

 

Mariner 9

The first spacecraft to orbit Mars had the bad luck to arrive at the planet during a massive 1971 dust storm that hid the entire surface. While it waited for the atmosphere to clear, the spacecraft turned its cameras on Phobos and Deimos and took the first close-up photographs of the Martian moons.

Mariner 9 would eventually return images of 80% of the planet's surface and show mission scientists a varied terrain that includes a volcano called Olympus Mons, which is three times as tall as Mount Everest, and geological features that may be ancient river channels.

 

Source