Mariner 9:
Overview
Mariner 9 was the first spacecraft to orbit another planet. It carried an instrument payload
similar to
Mariners 6 and 7, but, because of the need for a
larger propulsion system to control the spacecraft in
Mars orbit, it weighed more than
Mariners 6 and 7 combined.
When Mariner 9 arrived at Mars, the atmosphere was so
dusty that the surface was obscured. This unexpected situation made a strong case for the
desirability of studying a planet from orbit rather than merely flying past. Mariner 9's
computer was thus programmed from Earth to delay imaging of the surface
for a couple of months until the dust settled.
After 349 days in orbit, Mariner 9 had
transmitted 7,329 images, covering over 80% of Mars' surface. The images revealed river
beds, craters, massive extinct volcanoes, canyons including
Valles Marineris, a
massive system of canyons over 4,000 kilometers [about 2,500 miles] long. The vast chasm is named in honor of the spacecraft. Mariner 9 also found evidence of wind and
water erosion and deposition, weather fronts, fogs, and more. Mars' tiny moons,
Phobos and
Deimos, were also photographed.
The findings from the Mariner 9 missions laid the groundwork for the
Viking program.
Visit the Mariner 9 Website
