The Opportunity Rover's Athena science investigation at Meridiani Planum, Mars

Area of Science:

• Planetary Science
• Geology
• Astrobiology

Background:

• The Mars Exploration Rover Opportunity surveyed Eagle crater and Meridiani Planum.
• Surface soils are basaltic sands with hematite-rich spherules and wind ripples.
• Exposed sedimentary rocks lie beneath the soil layer.

Purpose of the Study:

• Investigate the geological composition and depositional environment of Meridiani Planum.
• Determine the role of water in the formation of Martian sedimentary rocks.
• Characterize the nature of hematite spherules.

Main Methods:

• In-situ analysis by the Opportunity rover.
• Geological mapping and observation of rock strata.
• Analysis of soil and rock composition, including sulfur and sulfate content.

Main Results:

• Sedimentary rocks are finely laminated, sulfur-rich, and contain abundant sulfate salts.
• Evidence of small-scale cross-lamination suggests deposition in flowing liquid water.
• Hematite-rich spherules, interpreted as diagenetic concretions, are embedded in and eroding from the rocks.

Conclusions:

• Meridiani Planum's rocks are a mix of chemical and siliciclastic sediments.
• Episodic shallow surface water, followed by evaporation and desiccation, formed these rocks.
• The presence of concretions further supports post-depositional diagenesis involving liquid water.