Photos Viking 1
The landers spent three and six years, respectively, trying to pry secrets out of the Martian desert. The hope was that chemistry experiments would provide definitive answers about whether or not life existed on Mars. But the rovers were looking at a sterile surface. Not surprisingly, the Viking metabolism and photosynthesis experiments turned up zilch, teaching NASA that it had much more to learn about Mars. "It's a complicated experiment to really identify life, even if you're sitting on top of it," said William Feldman, a reseacher with the Tucson, Ariz.-based Planetary Science Institute. For more than a decade, there was little discussion about the prospects of life on Mars. Then, in 1996, NASA announced it was studying a Mars meteorite that may contain fossilized bacteria. Though the studies remain controversial today, the issue reopened debate about life on Mars. In 1997, NASA's Pathfinder mission returned to Mars with an expanded quest to understand the planet's evolution. Subsequent orbiters and rovers have helped flesh out a history of a warmer planet that at one time may have had more water than Earth. Scientists don't know what happened to Mars' water and they don't know if it ever was on the surface long enough for life to evolve. NASA hopes more answers soon will be coming from Phoenix. This article is the third in a series about NASA's upcoming Mars Phoenix mission Discovery News will be blogging live from the Phoenix flight control center at the Jet Propulsion Laboratory in Pasadena, Calif., beginning Thursday, May 22. Related Links: Irene Klotz's blog: Free Space |
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