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05 March 2004

Liquid water altered rocks on Mars?

by Forrest M. Mims III

On 2 March, the Jet Propulsion Laboratory announced the likelihood that the rocks in the rim of the small crater being thoroughly explored by the Mars rover Opportunity were once soaked in liquid water.

This important finding is based on obvious laminations in the rocks and their high sulfur content. Other clues include many small voids in rocks and possible ripple indications in a rock.

Many small sphere-shaped rocks litter the area. Dubbed "blueberries," they are from 1 to 2 millimeters in diameter. According to Dr. Hap McSween, a rover science team member from the University of Tennessee, Knoxville, "A number of straightforward geological processes can yield round shapes." According to a JPL media release, McSween explained that a possible explanation for the blueberries is accretion under water. However, McSween explained, apparent pores in the "blueberries" suggest they might be byproducts of meteor impacts or volcanic eruptions.

Opportunity has completed most of its exploration of the shallow crater in which it landed and is now preparing to roll onto the surrounding sandy plain.

On the other side of Mars, Spirit has completed grinding a disk-shaped depression into a rock named Humphrey. Soon it will resume its journey across the rock strewn desert to a crater named
Bonneville.

The image above and all other raw images from Opportunity are at http://marsrovers.jpl.nasa.gov/gallery/all/opportunity.html.