Saturday, August 21, 2010

Life on Mars?

I just read an article called “It’s Alive” from the June 2010 issue of Discover Magazine. The author postulates that, according to some scientists, the case for life on Mars has already been settled. In 1976, the probe Viking I gathered samples of Martian dirt and tested for life. In one test, engineer Gilbert Levin put nutrients spiked with radioactive material in the dirt. If there were bacteria in the dirt, they would ingest the nutrients and exhale trace radioactive material. The first trial detected radioactivity. As a check, Levin did a second trial in which the dirt was superheated to kill off any bacteria before adding the radioactive nutrients. This trial did not detect any radioactive respiration. Since this was the only Viking test to support life on Mars, scientists assumed that some nonbiological reaction led to Levin’s results. However, in 1976, the assumption was that organic material is rare in the galaxy. Since then, astronomers have discovered organic material on Saturn’s moon Titan, on comets and meterorites, even in interstellar clouds 26,000 light years from Earth. After years of being overlooked, maybe someday Gilbert Levin will be proven right about life on Mars just like Alfred Wegener was proven right about continental drift after many decades. Lesson to all of us: stick by your conclusions if they are supported by evidence.

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