Open AccessTopography of valley networks on Mars from Mars Express High Resolution Stereo Camera digital elevation models
Author(s) -
Ansan Véronique,
Mangold Nicolas,
Masson Philippe,
Gailhardis Evelyne,
Neukum Gerhard
Publication year - 2008
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2007je002986
Subject(s) - geology , digital elevation model , noachian , mars exploration program , altimeter , bedrock , hesperian , impact crater , elevation (ballistics) , plateau (mathematics) , geomorphology , landform , lidar , fluvial , terrain , martian , remote sensing , geometry , astrobiology , geography , cartography , mathematical analysis , physics , mathematics , structural basin
Martian valley networks have been identified mainly in the Noachian heavily cratered uplands. The geometry of valley networks can be studied using Mars Orbiter Laser Altimeter (MOLA) altimetry, which is sufficient to map large valleys without a detailed 3‐D shape of valley networks. Imaging from the Mars Express High Resolution Stereo Camera (HRSC) is used to generate digital elevation models (DEMs) with resolution ≤50 m and vertical accuracy <60 m. We studied valleys near Huygens crater and in the Aeolis region both in the Noachian bedrock and on the West Echus plateau in Hesperian bedrock. HRSC DEMs in these areas show that (1) drainage density is 3 times higher than is observed in MOLA data, (2) degree of ramification is 1 order more than with MOLA, (3) transverse valley profiles show a V shape more accurately and a minimum depth of ∼20 m, and (4) higher drainage density shows greater headward extension that is not correlated to greater valley depth. The deepest valleys (400 m) are found in the Huygens region, where the density in the DEM is 0.1 km −1 , compared to shallow valleys (<100 m) of the Echus region, where the density is higher (∼0.3 km −1 ). These regional differences are due to spatially variable preservation and bedrock lithology. Longitudinal profiles suggest variations in duration of activity: profile concavity is only developed in some Noachian terrains. Valleys visible in HRSC images correspond to topographic features in DEMs showing the same geometry as terrestrial valleys thought to be formed by overland flows and seepage.