Introduction - Dune Worlds: How Windblown Sand Shapes Planetary Landscapes - page 4

Fig. 1.3 A radar image of a region of Titan's surface, about 150 km
across, from the Cassini spacecraft. The dark stripes are linear sand
dunes, about 1 km wide, snaking around a bright highland (shaped a

little like a snout) at the right. Similar deviation of dunes by

topographic obstacles is seen on Earth (Fig. 12.10 ) . Image by

R. Lorenz and the Cassini RADAR Team

Fig. 1.4 A schematic of the fundamental environmental features of
planets with dunes. While Mars' atmosphere is thin today, it may have
been substantially thicker in the past, perhaps making it easier to
transport sand. A pressurized lander or base on the moon would see a
gravity the same as Saturn's moon Titan, but with thinner air. The faint

diagonal lines are a crude indication of equal transportability; Venus
and Titan can move sediments with the gentlest winds, whereas today
very violent winds are needed to launch sand into the air on Mars.
These parameters are explored in more detail in Chap. 4