Fifty years ago this day, Mariner 9 became the first spacecraft to orbit another planet. Mariner 9 arrived at Mars after a 167-day flight on November 14, 1971. When it arrived, a global dust storm was raging on the planet, so it had to wait out the storm before any useful pictures could be taken. During its orbital tour of duty, Mariner 9 returned 54 gigabits of information to eager scientists on Earth, including 7,329 images of the red planet and its moons.
Mariner 9 was powered by 14,742 solar cells on four solar panels. The solar panels generated 500W of power while the spacecraft orbited Mars. A 20 amp-hour nickel cadmium battery stored the energy produced by the solar panels. The onboard computer had just 2K of memory (long before the days of “bloatware”), and an onboard digital reel-to-reel tape recorder was used to store data for later radio broadcast back to Earth.
Mariner 9’s mission to Mars ended on October 27, 1972 when it ran out of nitrogen gas for the attitude control jets. Mariner 9 remains in orbit around Mars, and is expected to burn up in the Martian atmosphere no sooner than the year 2022.