In 1965, the Mariner 4 space probe conducted a “flyby” of Mars, approaching within 6,100 miles (9,850 km) and transmitting 22 photographs back to Earth. These grainy black and white images, broadcast on television and printed in newspapers and magazines, surprised most viewers with their revelation that Mars is almost as heavily cratered as the Moon. In fact, the grim panoramas shot by Mariner were far more reminiscent of lunar wastelands than of the ruddy, Arizona-like Mars of science fiction. Not only were there no canals or ruined cities; Mars seemed downright ugly. These 22 photos de-romanticized the planet for a decade, until the closer-in, higher resolution, full-color images transmitted by the Viking missions corrected that misconception. Mars is indeed as colorful, with mountains as grand and canyons as rugged, as any pulp artist could have dreamed.
On the left is a fine example of Mariner 4's Mars: a photograph of craters in Memnonia Fossae. On the right is a photograph of another region of Memnonia Fossae, taken by the Viking spacecraft in 1998. Mars has now been restored to its traditional status as the Red Planet. Although craters are much in evidence, and canals are nowhere to be seen, the varied ochre terrain could never be mistaken for the Moon. The valley crossing the center of the image was evidently formed by volcanic and tectonic activity. Various features of the landscape may even have been shaped by flowing water, bringing us back to Percival Lowell's vision of a desert planet barely irrigated by impermanent waterways. Images courtesy NASA/JPL-Caltech.
