Introduction - Dune Worlds: How Windblown Sand Shapes Planetary Landscapes - page 11

Fig. 1.16 The 'Star Wars' film set near Tozeur, Tunisia. A set of
buildings (used to portray the city of Mos Espa on the planet Tatooine
in 'Star Wars, Episode 1') makes convenient reference marks to track
the migration of nearby dunes. The slip face of a barchan dune, about
20 m away from the set when this picture was taken in 2009, can be

seen behind the first author who is standing next to a 'moisture
vaporator' (sic). The dunes have been measured (Fig. 9.8 ) to move at
about 15 m/year, threatening the site with erosion and burial. Photo
R. Lorenz/J. Barnes

In fact, it was one of Rommel's most daring adversaries,
Brigadier Ralph Bagnold, who first made a systematic study
of sand transport and dunes as a physical process. Bagnold
explored the deserts prior to WWII, and his initial curiosity
about desert landforms motivated him to investigate the
physics underlying wind-induced particle motion, both in a
laboratory of his own design and through fieldwork in
deserts around the world. Bagnold's seminal book, The
Physics of Wind Blown Sand and Desert Dunes (1941), is
the starting point for all modern investigations of the geo-
morphology of sand dunes and sand deposits. Bagnold
instigated the famous 'Long Range Desert Group'
employing special vehicles and tactics and using his desert
knowledge to prevent Rommel invading British Egypt by

making deep strikes behind enemy lines across desert

thought to be impassable.
Similar challenges in locomotion are encountered in
snow, and now in traversing the loose, dry terrain on Mars.
The difficulties of negotiating noncohesive ground have
even claimed their first victim on another world. The Spirit
rover (Fig. 1.14 ) at the Gusev crater on Mars got stuck in
soft ground in an orientation that did not let it generate
enough solar power to survive the winter.
Sand giving way under one's wheel s or feet is one set of
problems; sand moving under the action of wind presents
others. Wind-blown snow presents a similar challenge,
prompting architecture that is aerodynamically designed to
prevent accumulation (Fig. 1.15 ) which can completely bury