R. B. Tucker

Variable features on Mars: Preliminary mariner 9 television results

Abstract Systematic Mariner 9 photography of a range of Martian surface features, observed with all three photometric angles approximately invariant, reveals three general categories of albedo variations: (1) an essentially uniform contrast enhancement due to the dissipation of the dust storm; (2) the appearance of splotches, irregular dark markings at least partially related to topography; and (3) the development of both bright and dark linear streaks, generally emanating from craters. Some splotches and streaks vary on characteristic timescales ∼2 weeks; they have characteristic dimensions of kilometers to tens of kilometers. The loci of these features appear in some cases to correspond well to the ground-based albedo markings, and the integrated time variation of splotches and streaks is suggested to produce the classical “seasonal” and secular albedo changes on Mars. The morphology and variability of streaks and splotches, and the resolution of at least one splotch into an extensive dune system, implicates windblown dust as the principal agent of Martian albedo differences and variability.

Variable features on Mars III: Comparison of Mariner 1969 and Mariner 1971 photography

Abstract Mariner 9 (M9) and Mariner 6 and 7 photography of common regions of Mars are compared, with appropriate attention to the photometric properties of the camera systems. The comparison provides a 2.5yr time baseline for study of variable albedo features. We find the development of bright streaks and patches, a phenomenon unobserved through the entire M9 mission; the evolution of dark crater splotches into dark streaks; and a planetwide increase in splotchiness. Yet, a large number of splotches and albedo boundaries remain fixed over the same period. Many of the observations are interpreted in terms of a global fallout and subsequent local redistribution of bright fine particulates raised by global dust storms.

A Mariner 9 Atlas of the moons of Mars

Abstract This paper contains a complete set of the best enhancements of Mariner 9 high resolution television pictures of Phobos and Deimos, consisting of 27 different views of Phobos, and 9 of Deimos. Pertinent data about the pictures are arranged in convenient tabular and graphical form.

Variable features on Mars. IV - Pavonis Mons

Abstract A remarkable set of albedo changes has been uncovered by Mariner 9 photography of the upper slopes of the shield volcano Pavonis Mons, near its summit caldera. The most likely explanation of the event is aeolian transport of fine-grained particles. Since the atmospheric pressure in this locality is ∼ 1.5 mb, minimum wind velocities above the surface boundary layer of about 110 m/s are necessary, corresponding to 0.51 of the speed of sound. Slope winds in this velocity range are expected near the upper flanks of major Martian volcanic constructs.