(CN) – Evidence of violent collisions with miniature planets suggest that the formation of Mars may have taken much longer than scientists have previously believed.
A study published Wednesday in Science Advances details how a team of researchers from the Southwest Research Institute undertook a deep analysis of Martian meteorites in an effort to better understand the still-mysterious origins of the red planet. Researchers found that notable amounts of metals and minerals found within the Martian rock samples suggest Mars may have been struck in its earliest years by a series of planetesimals, small planet-like bodies that are typically no larger than half the size of our moon.
While scientists have previously speculated it likely took a relatively speedy 2 to 4 million years for Mars to fully form, this new data could imply that it took the planet far longer to eventually settle – possibly as long as 20 million years.
Simone Marchi of the Southwest Research Institute and lead author of the study says these drastic planetary collisions not only point to a far longer growing timeframe for Mars, but as well likely had a remarkable influence over the overall structure of Mars as we know it.
“Our model envisions one to three large (1,000-2,000 km in diameter) collisions on early Mars. These early, large collisions must have had a tremendous effect on Mars' primordial atmosphere and surface volatile budget, including water. More work is needed to fully unravel these effects, but I believe current Mars would look radically different had those collisions not taken place,” Marchi said in an email.
Researchers say they were able to make these observations and fill in so many critical gaps in the billions-of-years long-history that is Mars by studying Martian rocks – even if such samples are notoriously limited. While Martian meteorites make up only the smallest fraction of all the meteorites that have struck Earth – around 61,000 meteorites have been discovered on Earth, and scientists believe only 200 came from Mars – the Martian meteorites can nonetheless tell an interesting story through one thing they all have in common: elements with a strong connection to iron.
The researchers say many of these Martian materials contain notable amounts tungsten, platinum and other elements with a strong affinity toward iron. Researchers suggest that because these kinds of elements have a natural tendency to retreat from a planet’s mantel into its iron core during its core’s formation, it is possible that collisions with planetesimals could explain why the elements are still so abundant.
Researchers suggest that if these compounds became mixed with Mars’s surface through the collisions after its core formed, radioactive-decay dating techniques would help to suggest a timeline in which Mars grew in the earliest days of our solar system at a far slower rate than has been previously suggested.
Researchers warn their findings, however, are not enough to fully establish a longer Mars formation timeline as absolute fact. The data available to them via Martian samples suggest that this extended timeline is a distinct possibility, and future study is required before more conclusive answers can become available.
Marchi says one of the biggest aids to solving these mysteries lies in greater access to Martian rocks themselves, such as those taken directly from the planet’s surface by retrieval missions. It is through these rocks, Marchi says, that scientists will be able to answer the many questions that continue to swirl around the long history of the red planet.
“Future access to more Martian rocks (including those gathered by sample-and-return missions) will provide important data to further constrain Mars' wild years,” Marchi said.
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