Mars: A Century of Exploration
Space Based Exploration Before Viking
The first close-up view of Mars was provided by the Mariner 4 spacecraft
which arrived at Mars on July 14, 1965 following an eight month journey
from Earth.
Mariner 4 was a flyby mission. It had a television camera aboard and
returned 21 pictures of the surface of Mars.
Mariners 6 and 7 were launched in February and March (respectively) of
1969.
Together, these fly-by spacecraft sent back 143 approach pictures
and 55
close-up pictures of Mars (the closest approach of either craft to Mars was
2,200 miles). These pictures revealled cratered deserts, terraced impact
regions, collapsed ridges and craterless depressions. The pair of
spacecraft also studied the Martian atmosphere and profiled its chemical
composition.
Launched in late May 1969, Mariner 9 became the first spacecraft to orbit
another planet. It spent a year orbiting Mars twice a day photographing
the surface and analyzing the atmosphere with infrared and ultraviolet
instruments. When Mariner 9 first arrived, Mars was almost totally obscured
by dust storms, which persisted for a month. But after the dust cleared,
Mariner 9 proceeded to reveal a very different planet - one that boasted
gigantic volcanoes
and a grand canyon stretching 3,000 miles across its
surface. More surprisingly, the relics of ancient riverbeds were carved in
the landscape of this seemingly dry and dusty planet.
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