Scientists are counting atoms to figure out when Mars last had volcanoes

Astroboffin-in-training makes dating breakthrough

Astroboffins have figured out a new way of dating planets and meteorites by counting individual atoms in rock samples snatched from the depths of space.

The atomic-scale imaging technique developed by University of Portsmouth scientists involves locating and counting individual atoms in planetary materials.

"Directly linking the structure and chemistry of minerals in this way opens up new opportunities to understand the spectacular complexity of planetary samples," the university said in a statement.

The research was led by Pompey PhD student Lee White, who said: "Because of the challenges scientists face in dating these complex materials, many meteorites could be older than previously thought. This could affect what we think regarding the age of the major planetary events in our solar system."

The technique is used to get one's head around the timing of major planetary events, such as the existence of active volcanoes on Mars and the point when magma oceans froze, two incidents that keep astroboffins exercising their little grey cells.

"Atom probe tomography provides 3D atom-by-atom imaging of materials with a uniquely powerful combination of spatial and chemical resolution," said the university. "It takes tiny grains of the mineral, approximately 1,000th the width of a human hair, and energises atoms one at a time using a laser."

Thanks to this technique researchers are able to construct 3D scale models of the material and then count individual uranium and lead atoms within it. In turn, that lets them carry out "accurate radiometric dating" of associated planetary events, something that White described as opening up "new avenues for dating highly deformed materials and provides an exceptional opportunity to accurately measure timings of major solar system events".

The full research paper, titled Atomic-scale age resolution of planetary events (DOI: 10.1038/NCOMMS15597) is due to be published in the journal Nature Communications. ®


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