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By Ker Than,
Posted: 2007-08-23 20:43:09
Filed Under: Science News
(Aug. 23) - Martian soil analyzed 30 years ago by NASA 's Viking landers might contain life, according to a new study.
The subfreezing, arid Martian surface could be home to microbes whose cells are filled with a mixture of hydrogen peroxide and water, said Joop Houtkooper of the University of Giessen, Germany.
Houtkooper reanalyzed data from the Gas Exchange (GEx) experiment carried out by the robotic landers and speculates the martian soil contained detectable amounts of life.
"It comes out to a little more than one part per thousand by weight, comparable to what is found in some permafrost in Antarctica," Houtkooper said.
The findings, presented this week at the European Planetary Science Congress in Potsdam, Germany are the latest in a long series of contenious claims about what the Viking landers might or could have found.
The GEx experiment detected unexplained rises in oxygen and carbon dioxide gas in soil samples collected on the martian surface. "If we assume these gases were produced during the breakdown of organic material together with hydrogen peroxide solution, we can calculate the masses needed to produce the volume of gas measured," Houtkooper explained.
Houtkooper and his colleague Schulze-Makuch from Washington State University speculate that a hydrogen peroxide-water based organism could survive the harsh martian climate where temperatures rarely rise above freezing and can reach -238 degrees Fahrenheit (-150 degrees Celsius) at the poles. The hydrogen peroxide would act like antifreeze for the cell, preventing its insides from crystallizing due to the cold.
Hydrogen peroxide-water solutions also tend to attract water, so the alien organisms could scavenge water molecules from the Martian atmosphere. However, if such creatures were exposed to too much water or atmospheres with high humidity, they could theoretically die through over-hydration.
The researchers think this could account for the anomalous GEx results. If during the soil sampling, the hydrogen peroxide-water microbes died, their cells would break down and release oxygen. Their organic compounds would react with the hydrogen peroxide to release carbon dioxide, water vapor and traces of nitrogen.
Houtkooper thinks the microbes could be detected by NASA's Phoenix lander, which launched on Aug. 4 and will arrive at Mars next May.
While rare, terrestrial organisms are known to use hydrogen-peroxide. The bombardier beetle, Brachinus Crepitans, uses a 25 percent solution of hydrogen peroxide to shoot steam into the face of pursuing predators.
"There does not appear to be any basic reason why hydrogen peroxide could not be used by living systems," Houtkooper said. "While organisms on Earth have found it advantageous to include salt in their intracellular fluids, hydrogen peroxide may have been more suitable for organisms adapting to the cold, dry environment of Mars."
Posted: 2007-08-23 20:43:09
Filed Under: Science News
(Aug. 23) - Martian soil analyzed 30 years ago by NASA 's Viking landers might contain life, according to a new study.
The subfreezing, arid Martian surface could be home to microbes whose cells are filled with a mixture of hydrogen peroxide and water, said Joop Houtkooper of the University of Giessen, Germany.
Houtkooper reanalyzed data from the Gas Exchange (GEx) experiment carried out by the robotic landers and speculates the martian soil contained detectable amounts of life.
"It comes out to a little more than one part per thousand by weight, comparable to what is found in some permafrost in Antarctica," Houtkooper said.
The findings, presented this week at the European Planetary Science Congress in Potsdam, Germany are the latest in a long series of contenious claims about what the Viking landers might or could have found.
The GEx experiment detected unexplained rises in oxygen and carbon dioxide gas in soil samples collected on the martian surface. "If we assume these gases were produced during the breakdown of organic material together with hydrogen peroxide solution, we can calculate the masses needed to produce the volume of gas measured," Houtkooper explained.
Houtkooper and his colleague Schulze-Makuch from Washington State University speculate that a hydrogen peroxide-water based organism could survive the harsh martian climate where temperatures rarely rise above freezing and can reach -238 degrees Fahrenheit (-150 degrees Celsius) at the poles. The hydrogen peroxide would act like antifreeze for the cell, preventing its insides from crystallizing due to the cold.
Hydrogen peroxide-water solutions also tend to attract water, so the alien organisms could scavenge water molecules from the Martian atmosphere. However, if such creatures were exposed to too much water or atmospheres with high humidity, they could theoretically die through over-hydration.
The researchers think this could account for the anomalous GEx results. If during the soil sampling, the hydrogen peroxide-water microbes died, their cells would break down and release oxygen. Their organic compounds would react with the hydrogen peroxide to release carbon dioxide, water vapor and traces of nitrogen.
Houtkooper thinks the microbes could be detected by NASA's Phoenix lander, which launched on Aug. 4 and will arrive at Mars next May.
While rare, terrestrial organisms are known to use hydrogen-peroxide. The bombardier beetle, Brachinus Crepitans, uses a 25 percent solution of hydrogen peroxide to shoot steam into the face of pursuing predators.
"There does not appear to be any basic reason why hydrogen peroxide could not be used by living systems," Houtkooper said. "While organisms on Earth have found it advantageous to include salt in their intracellular fluids, hydrogen peroxide may have been more suitable for organisms adapting to the cold, dry environment of Mars."
