Navigation bar Locations of visitors to this page
Oded Aharonson


Associate Professor of
Planetary Science

B.S. 1994, Cornell University

M.Eng. 1995, Cornell University

Ph.D. 2002, Massachusetts Institute of Technology


Planetary Geomorphology

Planetary Geomorphology

A history of processes acting through time is recorded in the morphology of planetary surfaces. Quantitatively describing this connection between form and process remains a formidable and fascinating challenge.

There are a few examples in which we have had recent success. The surface of Mars has been revealed in exquisite detail due to observations by an instrument suite on board the Mars Global Surveyor (MGS). Analyses of these data are ongoing. The Mars Orbiter Laser Altimeter (MOLA) permitted construction of topographic maps of an unprecedented accuracy and resolution. Statistical properties of the surface have been constrained, as have roughness properties over many scales. The map below summarizes the surface roughness by plotting the Inter-Quartile Scale (IQS) of the elevation distribution, obtained from MOLA elevations spaced by ~300 m, and binned in 35-km windows. This robust measure is insensitive to outliers in the distribution, and hence provides a useful quantification of the topographic variations.  Prominent features, such as 1. Olympus Mons, 2. Alba Patera, 3. Valles Marineris, 4.Sinus Meridiani, 5. the hemispheric dichotomy boundary, 6. Hellas rim, and 7. Olympia Planitia, have distinct roughness signatures.

The geologic and morphologic characterization of potential landing sites is of particular importance, for both scientific and practical reasons. Among the many motivations for this characterization, are the selection of scientifically rich sites, the testing and calibration of remote sensing predictions with ground truth, and the ascertaining of potential hazards for landers and rovers. The most likely landing site for the Mars Environmental Rover mission due to launch in 2003 is in Sinus Meridiani. The observation of a Hematite deposit there has led to a suggestion that a standing body of water was responsible for the iron oxidation. The map shown below demonstrates that the region's present-day topography does not form a closed basin, but rather has a westerly tilt. Sliding the pointer over the image will reveal contours of IQS surface roughness as well as the spectrally mapped location of the Hematite deposits. Note the close correspondence of the Hematite unit with a smooth area of IQS < 20-m. The possibility of a ancient body of water at this site is supported if the unusual smoothness is due to sedimentation in an aqueous environment.

We have also carried out analysis of slopes using data r eturned from Asteroid 433 Eros by the Near Earth Asteroid Rendez-vous (NEAR) mission's Laser Ranger (NLR). The shape of Eros is complex, and determining slopes, or even the direction of the gravity vector, can be tricky. Dividing the surface into roughly plates of roughly equal area helps, and by rolling the pointer over the image below, the computed slope histogram is revealed. Evidently, Eros possesses some slopes steeper than the angle of repose for most unconsolidated materials.

More information about this and other research is available in the form of published manuscripts here.