The enigmatic Martian asteroid ALH84001, which has been thought by some scientists to contain proof of life on Mars, may prove to be less extraordinary given the results of a recent study involving distant stars.
A team of scientists from the University of Amsterdam revealed today in the scientific journal Nature that carbon-based compounds like those inside the Martian asteroid have also been found in two faraway stellar nebulas. Until this discovery, it was thought that all carbonates required liquid-water environments to develop.
Now, the carbonates in the meteorite may be inconclusive in proving that liquid water -- and therefore a life-giving environment -- existed on the Red Planet, say the scientists. The carbonates could likely have come from interstellar locales instead.
On Earth, carbonates form when carbon dioxide gas dissolves in water. This mixing forms charged carbonate ions that can bind to either calcium or magnesium. England's White Cliffs of Dover are arguably the world's most famous calcium carbonate landmark.
Until now, non-Earth carbonates have been found only in meteorites and interstellar dust, which scientists presumed were remnants from watery locales on ancient Mars or other planetary bodies.
Finding and dating these carbonates led to presumptions about the timing of planet formation and where liquid water developed.
"The theory goes that planet-like masses formed about 20 million years after the coagulation of dust grains in our solar system," said lead researcher Ciska Kemper. "And this is based on the presence of carbonates found in meteorites."
The reliance on carbonate materials as the mile marker for solar system development was based on this idea that carbonates require liquid water to develop, and that liquid water only exists in the presence of planetary masses.
"As far as Mars is concerned, there is a lot of additional evidence for water being there at one time," Kemper said. "But the history of solar system should be reconsidered. These kinds of dates may prove untrue if carbonates are of a stellar, not planetary formation."
The Dutch team found the surprise carbonates in the dusty nubulea of two fading stars, NGC6302 and NGC6537, with the infrared spectroscope on the European Space Agency's Infrared Space Observatory.
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