Geoscience Reference
In-Depth Information
Loose material from radar data and
Venera
images appear
to be only a minor component of the surface, but scat-
tered dune fields have been observed and streaks of bright
material downwind of craters are not uncommon (1992,
1997; Greeley, Bender and Thomas, 1994). Two notable
dune fields, Aglaonice and Meshkenet, are located near
Aglaonice Crater and Meshkenet Tessera, respectively. It
is possible that radar look-angle effects may result in the
underrepresentation of dunes in the radar images (Weitz
et al.
, 1994).
Possible yardangs have been reported from near Mead
Crater (Greeley
et al.
, 1992, 1997; Greeley, Bender and
Thomas, 1994). Clear signs of aeolian erosion, such as
ventifacts or microyardangs are absent in the surface im-
ages (Trego, 1992). It is likely that many more aeolian
features occur at scales too small to be resolved by the
Magellan
radar; data on these await more surface images,
higher resolution radar surveys or descent images from
future missions.
Analogue research allows the geomorphologists to
study terrestrial counterparts of extraterrestrial processes.
It is particularly helpful in relation to Mars, where the
literature is extensive but biased towards North American
examples. Much more work needs to be done examining
geomorphic analogues for martian features from other
continents. In particular, I would emphasise the value of
studying cold desert processes, often sadly neglected in al-
most all reviews of both arid and periglacial geomorphol-
ogy. However, analogue research is not limited to martian
landforms but also to those of Titan, where there are ex-
cellent terrestrial counterparts to many features, especially
the longitudinal dunes. Such analogue research not only
provides insights into extraterrestrial processes but stim-
ulates new perspectives on terrestrial geomorphology.
References
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Bourgeois, O., Lopez, T., Le Mouelic, S.
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the 39th Lunar and Planetary Science Conference, Abstract
5.7.5
Summary
With at most only a minor role played by traces of liquid
phases, Venus is probably the most arid planet in the solar
system.
5.8
Future Directions
Extraterrestrial research opportunities for arid geomor-
phologists are extensive. Mars, with ongoing surface and
orbital missions and a succession of future missions be-
ing planned, offers the most possibilities. The data archive
from previous missions is immense and barely examined.
At present there are no plans to return to Venus, although
missions are being studied. Nevertheless, scope exists for
further research on the
Magellan
data set and the
Venera
surface images. With Titan it is unlikely we will see further
images from the surface for many decades hence. How-
ever, radar mapping by the
Cassini
spacecraft is ongoing
and much work still needs to be done.
Two fruitful avenues of terrestrial research are the ex-
perimental modelling of planetary surface conditions and
the search for terrestrial analogues. Modelling of the sur-
face conditions on Mars, Titan or Venus allows processes
to be studied and hypotheses tested. I suggest that stud-
ies of rock or ice breakdown under the surface condi-
tions of these bodies and the interaction of liquids other
than water with surface materials may be particularly
