Pathfinder Rover Finds Links To Earth’s Past In Martian Rocks

The Mars Pathfinder’s foot-high Sojourner rover has now found two distinct types of rocks on the Red Planet, one Earthlike and full of silicon, the other inexplicably high in sulfur.

Tom Economou, a University of Chicago scientist working with the rover’s alpha proton X-ray spectrometer, said Wednesday that a new analysis of the rock called Shark showed strong similarities to Barnacle Bill, one of the rover’s earliest targets.

Both Barnacle Bill and Shark contain higher-than-expected proportions of silicon - significant because it indicates repeated heating and cooling inside the planet’s crust, a process that formed many rocks on Earth.

But even more mysterious has been the chemical analyses of two other Mars boulders, Yogi and a recently examined rock called Wedge. They proved to be lower in silicon but high in sulfur. Sulfur would be highly unusual in rocks assumed to be volcanic, Economou said.

“It’s too soon to speculate about the processes that formed these rocks,” Economou said.

Project scientist Matthew Golombek said it’s possible they could be sedimentary rocks formed from layers of soil laid down by water, or a product of sulfur mixed into volcanic rock, or the result of meteoric impacts delivering sulfur to sedimentary rocks.