Mars photos

All 22 of the photographs taken by the Mariner IV space probe were released to the public at the end of July, together with a preliminary analysis of the information obtained from the photographs. This was followed by a paper in the August 6 issue of Science by Robert B. Leighton and his collaborators at the California Institute of Technology. The photographs were taken on July 15 as Mariner passed Mars at a distance ranging from 17 000 to 20 000 km. Pictures from the beginning and end of the series seem to lack definition, probably because of lighting effects (brightness at the beginning and darkness as the probe crossed the planet's sunset terminator), but surface features show up clearly in the images belonging to the middle of the series, and these yielded the big surprise: impact craters.