Viking Data Still Cause Stir About Mars Life

NASA recently posted on its Web site detailed data collected at Mars 25 years ago by life-detection experiments aboard the Viking spacecraft. The scientific community’s judgment on those findings is one of the longest running and most contentious debates in space science. In 1976, two ingenious spacecraft soft-landed on Mars. Each was equipped with a miniature biology laboratory packed into less space than a domestic microwave oven. The three biology experiments within the package each produced some positive results that might have been associated with living organisms but the overall verdict at the time was that these results were caused by chemical rather than biological processes. All these years later, scientists continue to glean information from the Viking data and still debate whether the results indicate life in the soils of Mars. The pendulum has swung back and forth between chemical and biological explanations for the Viking results.