Looking for Life on Mars:
Fossils Fuel the Search

By Lynne L. Hall
Little green men from the Red Planet. Menacing creatures with melon heads on cornstalk necks, eyes the size of walnuts and antennae sprouting like horns. Monsters that travel in Frisbee ships and wield cheesy-looking ray guns in their quest to conquer Earth. This, thanks to Hollywood, was the popular image of life on Mars until the Viking spacecraft landed on Mars, and, finding it uninhabitable, disappointed scientists and moviemakers alike. End of story? Hardly, say UAB professors Thomas Wdowiak, Ph.D., and David Agresti, Ph.D. Forget little green men and think fossilized bacteria instead. Wdowiak and Agresti are members of a NASA team that is beginning the search for life on Mars-the sequel. This time, no one is looking for alien life forms. Indeed, no one is looking to find living organisms. This time, the search is for evidence that life existed on Mars billions of years ago. Back then, Mars could have been much warmer and much wetter than it is today, says Wdowiak, an astrophysicist in UAB's physics department. "Before the atmosphere on Mars was lost, it's possible that life on that planet evolved to the bacterial stage-much as it did here on Earth. Today, instead of looking for life, we're looking for fossils."
Clues From the Deep
The current idea that life once existed on Mars was born from the discovery, on Earth, of bacterial life around deep-sea vents-underwater geysers-two miles below the ocean's surface. Scientists were surprised to find that these bacteria were getting their energy not from photosynthesis, the basis for the Earth's ecosystem, but from sulfurous minerals being spewed from the vents. This sulphur cocktail, combined with high heat produced from radioactive materials inside the Earth, was producing an ecosystem completely independent of the sun. "To anyone interested in exobiology-the search for life on other planets-this was a major discovery," says Wdowiak. "These same conditions can exist on other planets, and Mars is an especially likely candidate, because there's evidence that there once were lakes, rivers, and possibly even an ocean on Mars," says Wdowiak. Another discovery from the deep-sea vents on earth spurred Wdowiak's and Agresti's interest: fossilized bacteria encased in a coating of nanometer-sized iron-oxide particles. They also found a similar situation in the hot springs of Yellowstone National Park. If similar iron-oxide particles exist on Mars, they could hold evidence of bacterial life. Pinpointing deposits of such iron oxide particles, which are 100 times smaller than bacteria, is the key to finding fossils on Mars, says Wdowiak. He says UAB is poised to take a leading role in the search because of a special spectrometer that detects iron particles (an instrument developed by Agresti in a NASA-funded project), and because of a recent $120,000 NASA grant to study how to find fossils on Mars (in collaboration with Jack Farmer, Ph.D., of the NASA Ames Research Center). In addition, Wdowiak, Agresti, and Sergey Mirov, Ph.D., have just been awarded a new NASA grant, budgeted at $312,000, to develop a laser Raman spectrometer capable of analyzing minerals (including minerals that can form fossils), hydrocarbons, and frozen materials such as water ice, CO2 ice ("dry ice"), and exotic mixes of frozen gasses found on comets. This new instrument could eventually be flown to Mars on NASA's contemplated "Mars 2001" mission.
What Puts the "Red" in the Red Planet?
That iron exists on Mars is not in doubt-it's what gives the planet its red appearance. But whether or not Mars has iron particles that are small enough to form fossils is one of the questions Wdowiak and Agresti hope to answer with their Mossbauer spectrometer. The spectrometer is capable of distinguishing between different types of iron minerals by probing with gamma rays and detecting wavelengths at which nuclei absorb gamma rays.
Coming Soon: Pathfinder
NASA is planning a series of Mars landings to explore the surface of Mars and to look for fossils. The first mission, called "Pathfinder," is scheduled for December 1996. Its goal is to explore the planet's surface and to scout locations, such as defunct hot springs, that might be good spots for fossil hunting. Landings are planned every two years until 2006. Through the years, Wdowiak and Agresti have built a close relationship with NASA, joining in its mission to explore the universe. Recently both were selected to serve in an advisory capacity on the NASA panel that will coordinate the 1998 Mars mission-an assignment that has them working at the highest levels within NASA and one they hope will lead to UAB's inclusion in future missions. So, maybe hunting for fossils on Mars isn't as dramatic as finding little green men, but for Wdowiak and Agresti, it's an exciting prospect.
These fossils from New Mexico, Arizona, Minnesota and South Africa suggest what fossils on Mars, if they exist, might look like.

Return To Space Menu.