May 19, 2008 -- Thirty-three years ago, NASA set out with grand ambitions to find life on Mars. Instead, scientists found a cold, dry desert with no atmosphere to stop solar ultraviolet radiation from sterilizing everything in sight.
Now, with NASA's Phoenix lander, set for a touchdown Sunday in the northern polar region of Mars, scientists better understand where to look for the next piece in the ongoing puzzle of whether life ever existed on the Red Planet.
"We're trying to find the places that were 'juicy' in terms of having the water and the material necessary to support life," said Phoenix co-investigator Ray Arvidson, with Washington University in St. Louis.
The Phoenix lander's mission is to dig beneath the Martian soil for ice and soil samples for analysis on site. The point of the research, which is expected to last three months, is to learn if conditions were ever suitable to support life: Is Mars' water in a form that can support life? Does it contain organic materials?
Actually looking for life is not part of the Phoenix mission.
"We want to get at the habitability issue and it's being done in a very proscribed way," Arvidson said. "Until we better understand where to go, I'm not sure the life-detection experiments would be worth the investment."
Much has changed since the heady days after the successful Apollo moon landings, when NASA dispatched a pair of expensive robots to look for life on Mars. Those missions included two orbiters to take pictures from above and two landers to put Mars under a microscope. Combined, the Viking twins cost NASA about $1 billion in the mid-70s, or more than $4 billion in today's dollars.
Discovery News will be blogging live from the Phoenix flight control center at the Jet Propulsion Laboratory in Pasadena, Calif., beginning Thursday, May 22. And The Science Channel will be covering the descent and landing live.
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.
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