Laboratory Studies - Dune Worlds: How Windblown Sand Shapes Planetary Landscapes - page 202

For a start, there is a great structural difference between
the pressure differential for Mars simulation (1 bar minus
6 mbar is *1 bar) and that for Venus (90 bar minus 1 bar is
89 bar, the pressure at about 1 km depth in the Earth's
oceans), so a Venus facility must have engineering remi-
niscent of a submarine, and a sturdy one at that.
Venus conditions were somewhat replicated in a small
wind tunnel (the Venus Wind Tunnel, VWT) set up in the
early 1980s at NASA Ames (Greeley et al. 1984a). (The
replication was 'somewhat' in that the high pressures and
gas composition was reproduced, but not the high temper-
ature.) The high pressures necessitate some very heavy-duty
pipework (see Fig. 17.13 ). The overall dimensions of the
tunnel are 6 m 9 2.3 m, although the working section is
quite small, and the gas flow is driven by a 1 horsepower
(750 W) DC electrical motor which can drive the flow at up
to 4 m/s. The test section where particle motion and bed-
form formation (see Figs. 4.16 and 5.7 ) was observed was
20 cm in diameter and 122 cm long.
The tunnel had been largely unused through the 1990s, but
following the interest in Titan aeolian processes, has been
recently refurbished with new instrumentation and is being
used for Titan conditions (again, replicating atmospheric
density but not temperature). Several other Titan chambers
exist in various facilities, but none have yet been used for
aeolian studies. (As an aside, the first author conducted some
experiments on the generation of waves in water at different
atmospheric pressures and, as a Titan analog, kerosene, in the
Marswit facility (Lorenz et al. 2005)). Note that it is generally
less easy to set up a Titan chamber than a Mars chamber.
First, the chamber must be rated for positive pressure (which
is more hazardous since a failing window will then blow

Fig. 17.13 Lasers are a feature of much modern instrumentation for
studying sand and dust transport. They also make for some appealing
photographs. Image courtesy of Jon Merrison

Fig. 17.14 The Venus Wind
Tunnel at NASA Ames. Note the
obviously heavy engineering. A
cart with instrumentation is in the
foreground. Image courtesy of
Ron Greeley