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Close-up view of the Nakhla Martian meteorite, fallen in Egypt in 1911.
Credit: NASA
New study reveals that organic molecules – compounds that on Earth may be related to life – enclosed in Mars meteorites could have formed on the red planet as a result of chemical reactions similar to those found in batteries on Earth.
Scientists have warned that these discoveries did not mean that there was life on Mars. Instead, they can show a new path for "building blocks of life" as we know it, as they formed on the red planet.
Organic molecules are the carbon-based chemicals that make up the essential elements of life, such as proteins and DNA. Earlier work had detected organic compounds in Martian meteorites, but researchers had long debated the origin of these molecules. [Photo Gallery: Images of Martian Meteorites]
In 2012, scientists discovered evidence that organic molecules from several Martian meteorites originated from Mars and were not contaminants of the Earth. However, they also discovered that these organic compounds did not have a biological origin – the researchers assumed they were formed from volcanic processes.
To better understand the origin of these organic molecules, the researchers studied three Martian meteorites. It was Nakhla, fallen to Egypt in 1911; Tissint, who fell in the Moroccan desert in 2011; and NWA 1950, which was found in the Atlas Mountains in Morocco in 2001.
Microscopic analyzes revealed that organic molecules in these rocks were often intertwined with minerals such as titanomagnetite, magnetite, pyrite and pyrrhotite, according to the researchers. The types of organic compounds found in these meteorites were very similar to those detected on the red planet by Mars Science Laboratory's Curiosity robot missions.
Scientists have noted that titanomagnetite is a catalyst capable of triggering chemical reactions. Given the specific molecules that the researchers found close to each other in the meteorite, they suggested that, on Mars, titanomagnetite catalyzed reactions between volcanic minerals, salty liquids and dissolved carbon dioxide in fluids brine, creating organic matter. These reactions are similar to those that occur regularly in batteries.
Earlier work to generate useful chemicals from carbon dioxide in the Earth's atmosphere has shown that such reactions are possible. However, this activity "was never supposed to exist in nature," Andrew Space, lead author of the study, astrobiologist at Washington's Carnegie Institution for Science, told Space.com.
This high resolution view of a Martian meteorite grain comes from a transmission electron micrograph (50 nanometer scale). Organic carbon layers are found between the fork-like "teeth", where they are formed when the volcanic minerals of the rock interacted with salt brine.
Credit: Courtesy of Andrew Steele
In summary, "it does not say that there is life on Mars, but shows a new way of building the foundations of life," Steele said. These discoveries could shed light on "the reactions that led to life on the primitive Earth," he added.
Scientists are currently exploring the organic chemicals that these reactions could produce on Mars. "The preliminary experiments have already produced methane in the lab," Steele said.
Future exploration of Mars and analysis of samples from the red planet could help determine whether these reactions are actually occurring in this region, the researchers added. If these works are confirmed, this work could help to uncover the background of organic materials that may exist on Mars in order to "differentiate possible Martian life from organic chemistry," Steele said.
Scientists detailed their findings online Oct. 31 in the journal Science Advances.
Follow Charles Q. Choi on Twitter @cqchoi. Follow us on twitter @Spacedotcom and on Facebook. Original article on Space.com.
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