Spring Break
Scientists expanding search for evidence of life on mars
Issue date: 3/1/07 Section: Science and Tech
Originally published: 2/28/07 at 11:10 PM EST Last update: 2/28/07 at 11:09 PM EST
Tullis Onstott, a geoscientist at Princeton University, has suggested sending a Mars rover that could drill down to the source of the methane to search for organic matter, dead or alive.
If found, such organisms would be similar to colonies of microbes called methanogens, which feed on methane below the ocean floor on Earth. Onstott has found many examples of what he calls "dark life" dwelling two miles down in South African gold mines.
"If you find good evidence of environments that support life in the deep subsurface of Earth, then the chances are high that you will find these environments beneath Mars as well," Onstott told the Princeton Weekly Bulletin.
In addition, scientists say there are ample sources of energy on Mars, even below the surface, where the sun never shines.
The source of underground energy is "no longer sunlight but the planet itself," Hoehler explained.
Mars' interior retained heat, a form of energy, from the time of its formation 4.5 billion years ago. Radioactive rocks also emit a steady stream of energetic particles.
"There is chemical energy inside the planet," Hoehler said. He likened it to "the planet's battery."
Mars also is loaded with iron, which combines with oxygen to give the planet its distinctive rust color.
"Oxidizing iron yields energy," said David Des Marais, a geochemist at the Ames Research Center. Sulfur also can combine with oxygen to produce energy.
"This is how a lot of things on Earth make a living," Des Marais said. Presumably the same iron and sulfur chemistry would work on Mars.
Another potential source of extraterrestrial food and energy is hydrogen, a gas that's starting to be used to power vehicles on Earth and also nourishes underground swarms of microbes.
"Hydrogen gas is like junk food to a lot of bacteria," Onstott said.
On Mars, hydrogen can be generated by the interaction of radioactive rocks and water.
"Hydrogen probably represents the most interesting prospective energy source for would-be Martian microbes, simply because it's always in the picture wherever rocks and water get together," Hoehler said.
If found, such organisms would be similar to colonies of microbes called methanogens, which feed on methane below the ocean floor on Earth. Onstott has found many examples of what he calls "dark life" dwelling two miles down in South African gold mines.
"If you find good evidence of environments that support life in the deep subsurface of Earth, then the chances are high that you will find these environments beneath Mars as well," Onstott told the Princeton Weekly Bulletin.
In addition, scientists say there are ample sources of energy on Mars, even below the surface, where the sun never shines.
The source of underground energy is "no longer sunlight but the planet itself," Hoehler explained.
Mars' interior retained heat, a form of energy, from the time of its formation 4.5 billion years ago. Radioactive rocks also emit a steady stream of energetic particles.
"There is chemical energy inside the planet," Hoehler said. He likened it to "the planet's battery."
Mars also is loaded with iron, which combines with oxygen to give the planet its distinctive rust color.
"Oxidizing iron yields energy," said David Des Marais, a geochemist at the Ames Research Center. Sulfur also can combine with oxygen to produce energy.
"This is how a lot of things on Earth make a living," Des Marais said. Presumably the same iron and sulfur chemistry would work on Mars.
Another potential source of extraterrestrial food and energy is hydrogen, a gas that's starting to be used to power vehicles on Earth and also nourishes underground swarms of microbes.
"Hydrogen gas is like junk food to a lot of bacteria," Onstott said.
On Mars, hydrogen can be generated by the interaction of radioactive rocks and water.
"Hydrogen probably represents the most interesting prospective energy source for would-be Martian microbes, simply because it's always in the picture wherever rocks and water get together," Hoehler said.
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