In 2011, nomads roaming the western Sahara encountered precious time capsules from Mars: coal-black chunks of a meteorite, strewn across the dunes. "Black Beauty," as the parent body came to be known, captivated scientists and collectors because it contained crystals that formed on Mars more than 4.4 billion years ago, making it older than any native rock on Earth. Jerome Gattacceca, a paleo-magnetist at the European Centre for Research and Teaching in Environmental Geo-sciences, hoped it might harbor a secret message, imprinted by the now-defunct mar-tian magnetic field-which is thought to have helped the planet sustain an atmosphere, water, and possibly even life. But when Gattacceca obtained a piece of Black Beauty and tried to decode its magnetic inscription, he found its memory had been wiped-Men in Black style-and replaced by a stronger signal. He instantly knew the culprit. Somewhere along its journey from Moroccan desert to street dealers to laboratory, the rock had been touched by strong hand magnets, a widely used technique for identifying meteorites. "It's a pity that, just by using magnets, we've been destroying this scientific information that was stored there for 4 billion years," Gattacceca says.
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