Mars Special Section: Opportunity at Meridiani Planum

The eleven papers in this Mars special issue, "Opportunity at Meridiani Planum," together with recent orbital observations, provide the first clear geological and geochemical documentation of water on Mars.

The results indicate that water was involved in the formation and alteration of layers of sedimentary rock. This finding in the 3 December 2004 issue of the journal Science is consistent with models of a warmer, wetter martian past, according to an overview article by Steven Squyres and colleagues and a "Perspective" article from Jeffrey Kargel.

The special section describes Opportunity's initial 90 martian solar days and includes documentation of the first close-up look at martian bedrock. While the researchers uncovered no evidence of life on Mars, Kargel cautions that — until we learn otherwise — scientists must assume that life exists on Mars, in order to protect Earth and any species that might be present on Mars.

In the previous Mars special issue in Science (6 August 2004, Volume 305, Number 5685), scientists described the volcanic rock rubble and inorganic soils that the rover Spirit encountered at Gusev Crater during its first 90 martian solar days.

See also an interview with Steve Squyres, professor of astronomy at Cornell University and scientific principal investigator for the NASA Jet Propulsion Laboratory's Mars exploration rover project. The telephone interview was conducted by AAAS senior writer Edward W. Lempinen in two installments, on 2 August and 5 August 2004.

— Daniel B. Kane

3 December 2004