Mariner Mars 1969: Atmospheric results

Results of investigation of probable atmospheric effects appearing in Mariner '69 TV pictures that have undergone noise removal and preliminary decalibration are described. Two distinct types of haze are distinguished: north polar haze, seen prominently against the face of the planet in blue photographs, and thin haze, usually identified by its appearance on the limb and not strongly colored. Thin haze is surprisingly widespread, particularly in the southern hemisphere. Discrete bright features, which may be evidence for condensation on the ground or in the atmosphere, are described. These occur where bright features have often been seen from earth, in a region where very large multiple-ringed structures seem to dominate the surface morphology. The speculation that these may be evidence for local water-vapor exchange between ground and atmosphere is raised, and some constraints on local subsurface water-vapor sources in the Mars tropics are described. Finally, some implications of the Mariner '69 results for atmospheric exploration by Mariner '71 are briefly discussed.