Sulfur-rich rocks in the "Columbia Hills" on Mars stand out in bright blue in this false-color image from the Spirit rover. Spirit used its rock abrasion tool, or "RAT" to grind a hole in the rock, nicknamed "Peace" in honor of Dr. Martin Luther King, Jr. The rock's high sulfur content and softness are probably evidence of past alteration by water.
Sulfur-rich rocks in the “Columbia Hills” on Mars stand out in bright blue in this false-color image from the Spirit rover. Spirit used its rock abrasion tool, or “RAT” to grind a hole in the rock, nicknamed “Peace” in honor of Dr. Martin Luther King, Jr. The rock’s high sulfur content and softness are probably evidence of past alteration by water.Image Credit: NASA/JPL/Cornell