The Mars meteorite ALH84001 never got hotter than 40 degrees Celsius on its journey to Earth. 16 million years ago, an asteroid struck the surface of Mars and hurled large amounts of rock into space. Among them was a potato-sized piece that ended its journey through space some 13, 000 years ago in the Antarctic. In 1996, the meteorite ALH84001 achieved spectacular fame when scientists believed that they had found fossilized microorganisms in it. Although the hopes were soon disappointed, but this seems not to be impossible. Benjamin Weiss of the California Institute of Technology believes that this meteorite never got warmer than 40 degrees Celsius. Thus, bacteria, spores or seeds could in principle survive the journey from Mars and perhaps even ground life on Earth.

Weiss investigated the Marsbrocken under the Ultra High Resolution Scanning Superconducting Quantum Interference Device Microscope (UHRSSM). With its help, tiny differences in the magnetic orientation of individual minerals can be investigated. As a result of heating, these differences are equalized. And this happened in the experiment already at temperatures from 40 degrees Celsius. The interior of the meteorite, from which the fine disks for the investigation originated, was therefore never exposed to higher temperatures after the asteroid impact on Mars. The life it contained would have had good chances of survival.

Although Weiss does not believe that ALH84001 is good for such surprises, life in this way could have come from Mars to Earth. Computer simulations show that since the formation of both planets about one billion tons of Martian rock came to Earth. And with great certainty it was once warm, humid and sunny on the red planet.

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Joachim Schüring

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