School of Earth and Atmospheric Sciences, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0340, USA e-mail: [email protected]
Gale crater formed from an impact on Mars ∼3.6 billion years ago. It hosts a central mound nearly 100 km wide and ∼5 km high, consisting of layered rocks with a variety of textures and spectral properties. The oldest exposed layers contain variably hydrated sulphates and smectite clay minerals, implying an aqueous origin, whereas the younger layers higher on the mound are covered by a mantle of dust. Fluvial channels carved into the crater walls and the lower mound indicate that surface liquids were present during and after deposition of the mound material. Numerous hypotheses have been advocated for the origin of some or all minerals and layers in the mound, ranging from deep lakes to playas to mostly dry dune fields to airfall dust or ash subjected to only minor alteration driven by snowmelt. The complexity of the mound suggests that multiple depositional and diagenetic processes are represented in the materials exposed today. Beginning in August 2012, the Mars Science Laboratory rover Curiosity will explore Gale crater by ascending the mound's northwestern flank, providing unprecedented new detail on the evolution of environmental conditions and habitability over many millions of years during which the mound strata accumulated.
(Received June 30 2012)
(Accepted July 27 2012)
(Online publication September 24 2012)