Who you calling old?

By directing energy beams at tiny crystals found in a Martian meteorite, a team of researchers determined that the most common group of meteorites from the Red Planet is, in fact, 4 billion years younger than many scientists believed.

Knowing this resolves a long-standing puzzle in Martian science and paints a much clearer picture of the planet's evolution that, based on their results, can now be compared to that of Earth, accordign to the researchers.

In the paper published in the journal Nature, the Western University-led team show that a representative meteorite from the Royal Ontario Museum's ever-increasing Martian meteorite collection started as a 200-million-year-old lava flow on the Red Planet's surface.

Furthermore, their analysis shows that the sample contains an ancient chemical signature indicating a hidden layer located well below the surface that is almost as old as the solar system.

The researchers also discovered crystals that grew while the meteorite was launched from Mars toward Earth. Based on this, they were able to narrow down the timing to less than 20 million years ago while also identifying possible launch locations on the flanks of the supervolcanoes at the Martian equator.

Lead author Desmond Moser and his group at Western's Zircon and Accessory Phase Laboratory (ZAPLab), one of the few electron nanobeam dating facilities in the world, determined the growth history of crystals on a polished surface of the meteorite. They did this by combining the long-established dating method of measuring radioactive uranium/lead isotopes with a recently developed mineral grain-scale technique at the University of California, Los Angeles that liberates atoms from the crystal surface using a focused beam of oxygen ions.

All told, Moser estimates there are roughly 60 Mars rocks dislodged by meteorite impacts that are now on Earth and available for study and that the approach pioneered by his group could be used on these and a much wider range of heavenly bodies.

"Basically, the inner solar system is our oyster. We have hundreds of meteorites that we can apply this technique to, including asteroids from beyond Mars to samples from the Moon," said Moser, who credits the generosity of the collectors that identify this material and make it available for public research.