Moving on Sand - Dune Worlds: How Windblown Sand Shapes Planetary Landscapes - page 256

Fig. 22.12 NASA's Mars
Exploration Rover Spirit slipped
in soft ground during short
backward drives on the 1886th
and 1889th Martian days, or sols,
of the rover's mission on Mars
(April 23 and 26, 2009). Spirit
used its front hazard-avoidance
camera after driving on Sol 1889
to get this wide-angle view,
which shows the soil disturbed by
the drives. Spirit drove 1.11 m
(3.6 ft) on Sol 1889 and 1.68 m
(5.5 ft) on Sol 1886. The rover
drags its right front wheel, which
no longer rotates. For scale, the
distance between the wheel
tracks is about 1 m (40 in.).
Image credit: NASA/JPL-Caltech
Fig. 22.13 A screen shot from
software used by the Mars
Exploration Rover team for
assessing movements by Spirit
and Opportunity illustrates the
degree to which Spirit's wheels
have become embedded in soft
material at the location called
'Troy'. The image simulates
Spirit's position on May 8, 2009,
during the 1900th Martian day, or
sol, of what was originally
planned as a 90-sol mission on
Mars. Image credit: NASA/JPL-
Caltech