Evidence for the prolonged presence of potentially-life-supporting, salty, acidic water on the surface of Mars claims top honors as the Breakthrough of the Year, named by Science and its publisher, AAAS, the nonprofit science society.

The findings from 2004 suggest that Mars was once a wet, warm place that could have been capable of cradling life billions of years ago, when life on Earth was getting its start.

This milestone plus nine other research advances make up Science's list of the top ten scientific developments in 2004, chosen for their profound implications for society and the advancement of science. The Top Ten list appears in the 17 December 2004 issue of the journal Science.

With the help of remote-sensing spacecraft, NASA's two hardy little robotic explorers performed the first true geologic field explorations on another planet.

The Opportunity rover discovered exposed bedrock at Eagle crater on Meridiani Planum that suggests a cyclical wet-and-dry history. The bedrock provides long-sought evidence for a prolonged wet and warm period on Mars.

On the other side of the Red Planet, the rover Spirit found evidence of shallow groundwater that may have transformed hundreds of meters of volcanic ash into soft, iron-rich rock.

Any martian life would have confronted a harsh environment dominated by salty, acidic waters that regularly dried up, but creatures capable of surviving or even thriving under such extreme conditions live here on Earth.

An international team of scientists outfitted the two identical Rovers with "eyes" that see in color, a magnifying glass, a grinding wheel for exposing fresh rock, an elemental analyzer, and two mineral-identifying instruments.

The Mars
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Contact: Jessica Lawrence-Hurt
jlawrenc@aaas.org
1-202-326-7088
American Association for the Advancement of Science
16-Dec-2004