During its wheeled treks on the Red Planet, NASA's Spirit rover may have encountered a potential signature of past life on Mars, report scientists at Arizona State University (ASU). To help make their case, the researchers have contrasted Spirit's study of "Home Plate" -- a plateau of layered rocks that the robot explored during the early part of its third year on Mars -- with features found within active hot spring/geyser discharge channels at a site in northern Chile called El Tatio. The work has resulted in a provocative paper: "Silica deposits on Mars with features resembling hot spring biosignatures at El Tatio in Chile." As reported online last week in the journal Nature Communications, field work in Chile by the ASU team -- Steven Ruff and Jack Farmer of the university's School of Earth and Space Exploration -- shows that the nodular and digitate silica structures at El Tatio that most closely resemble those on Mars include complex sedimentary structures produced by a combination of biotic and abiotic processes. "Although fully abiotic processes are not ruled out for the Martian silica structures, they satisfy an a priori definition of potential biosignatures," the researchers wrote in the study.

During its wheeled treks on the Red Planet, NASA's Spirit rover may have encountered a potential signature of past life on Mars, report scientists at Arizona State University (ASU). To help make their case, the researchers have contrasted Spirit's study of "Home Plate" -- a plateau of layered rocks that the robot explored during the early part of its third year on Mars -- with features found within active hot spring/geyser discharge channels at a site in northern Chile called El Tatio. The work has resulted in a provocative paper: "Silica deposits on Mars with features resembling hot spring biosignatures at El Tatio in Chile." As reported online last week in the journal Nature Communications, field work in Chile by the ASU team -- Steven Ruff and Jack Farmer of the university's School of Earth and Space Exploration -- shows that the nodular and digitate silica structures at El Tatio that most closely resemble those on Mars include complex sedimentary structures produced by a combination of biotic and abiotic processes. "Although fully abiotic processes are not ruled out for the Martian silica structures, they satisfy an a priori definition of potential biosignatures," the researchers wrote in the study.