Editor's Summary

22 December 2005

The waters ran shallow

Surface features at the landing site of Opportunity, the Mars Exploration Rover, have been taken as evidence that liquid water was once abundant on Mars. But two groups now present alternative explanations of the layered structures and mineral compositions of the Meridiani Planum that do not involve a standing body of liquid water. Turbulent flow of rock fragments, salts and ice produced by meterorite impact and deposition of volcanic material followed by reaction with condensed sulphur dioxide- and water-bearing vapours, are offered as alternative explanations for the observations.

Article: Impact origin of sediments at the Opportunity landing site on Mars

L. Paul Knauth, Donald M. Burt and Kenneth H. Wohletz

doi:10.1038/nature04383

Abstract | Full Text | PDF (530K)

Letter: A volcanic environment for bedrock diagenesis at Meridiani Planum on Mars

Thomas M. McCollom and Brian M. Hynek

doi:10.1038/nature04390

First paragraph | Full Text | PDF (173K) | Supplementary information