Search Publications
Planetary surface dating from crater size-frequency distribution measurements: Partial resurfacing events and statistical age uncertainty
Neukum, G.; Michael, G. G.
We describe the procedure to fit a cumulative production function polynomial to a partial crater size-frequency distribution. The technique is of particular use in deriving ages for surfaces which have undergone partial resurfacing events: namely, erosional or depositional events which have affected a limited diameter range of the crater populatio…
Geologic history of Mars
Head, James W.; Carr, Michael H.
Mars accumulated and differentiated into crust, mantle and core within a few tens of millions of years of Solar System formation. Formation of Hellas, which has been adopted as the base of the Noachian period, is estimated to have occurred around 4.1 to 3.8 Gyr ago, depending on whether or not the planet experienced a late cataclysm. Little is kno…
Ancient ocean on Mars supported by global distribution of deltas and valleys
Hynek, Brian M.; di Achille, Gaetano
The climate of early Mars could have supported a complex hydrological system and possibly a northern hemispheric ocean covering up to one-third of the planet's surface. This notion has been repeatedly proposed and challenged over the past two decades, and remains one of the largest uncertainties in Mars research. Here, we used global databases of …
Depth of the Martian cryosphere: Revised estimates and implications for the existence and detection of subpermafrost groundwater
Heggy, Essam; Clifford, Stephen M.; Lasue, Jeremie +3 more
The Martian cryosphere is defined as that region of the crust where the temperature remains continuously below the freezing point of water. Previous estimates of its present thickness have ranged from ∼2.3-4.7 km at the equator to ∼6.5-12.5 km at the poles. Here we revisit these calculations, review some of the assumptions on which they were based…
Northern mid-latitude glaciation in the Late Amazonian period of Mars: Criteria for the recognition of debris-covered glacier and valley glacier landsystem deposits
Head, James W.; Marchant, David R.; Dickson, James L. +2 more
Lobate debris aprons (LDA) and lineated valley fill (LVF) have been known to characterize the mid-latitude regions of Mars since documented by Viking; their flow-like character suggested that deposition of ice in talus pile pore space caused lubrication and flow during an earlier climatic regime. A number of factors have remained uncertain, howeve…
Evidence for Hesperian impact-induced hydrothermalism on Mars
Tornabene, Livio L.; Roush, Ted L.; Bishop, Janice L. +7 more
Several hydrated silicate deposits on Mars are observed within craters and are interpreted as excavated Noachian material. Toro crater (71.8°E, 17.0°N), located on the northern edge of the Syrtis Major Volcanic Plains, shows spectral and morphologic evidence of impact-induced hydrothermal activity. Spectroscopic observations were used to identify …
A cold and wet Mars
Fairén, Alberto G.
Water on Mars has been explained by invoking controversial and mutually exclusive solutions based on warming the atmosphere with greenhouse gases (the "warm and wet" Mars) or on local thermal energy sources acting in a global freezing climate (the "cold and dry" Mars). Both have critical limitations and none has been definitively accepted as a com…
Detection of Hydrated Silicates in Crustal Outcrops in the Northern Plains of Mars
Bibring, J. -P.; Poulet, F.; Carter, J. +1 more
The composition of the ancient martian crust is a key ingredient in deciphering the environment and evolution of early Mars. We present an analysis of the composition of large craters in the martian northern plains based on data from spaceborne imaging spectrometers. Nine of the craters have excavated assemblages of phyllosilicates from ancient, N…
Topography of Mars from global mapping by HRSC high-resolution digital terrain models and orthoimages: Characteristics and performance
Jaumann, R.; Oberst, J.; Preusker, F. +7 more
We report on the results of the Mars Express High-Resolution Stereo Camera (HRSC) experiment pertaining to one of its major aims, mapping the surface of Mars by high-resolution digital terrain models (DTM, up to 50 m grid spacing) and orthoimages (up to 12.5 m resolution). We introduce the specifications and characteristics of these data products …
A comparison of global models for the solar wind interaction with Mars
Kallio, E.; Barabash, S.; Lammer, H. +24 more
We present initial results from the first community-wide effort to compare global plasma interaction model results for Mars. Seven modeling groups participated in this activity, using MHD, multi-fluid, and hybrid assumptions in their simulations. Moderate solar wind and solar EUV conditions were chosen, and the conditions were implemented in the m…