This could be why Mars is so metal

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Jul 28, 2017

Mars is pretty hardcore when you consider the fact that its wide expanses of reddish dust hide a dragon’s hoard of rare metals beneath the surface. Now new research might actually have an explanation of why the Red Planet rocks so hard.

In a universe of hypotheses that has explored everything from extraterrestrial plate tectonics to primordial oceans, scientists have lately been gravitating toward the possibility of a massive asteroid collision, aka the “single impact hypothesis." Scientists Ramon Brasser and Steven Mojzsis have used this hypothesis to shed more light on the Martian landscape, minerals, and moons in a paper recently published in Geophysical Research Letters.

"We showed in this paper—that from dynamics and from geochemistry — that we could explain these three unique features of Mars," said Mojzsis.

In a solar system that was still relatively young, an object around the size of dwarf planet Ceres (which resides in the asteroid belt Mars is thought by some to have originated from) crashed into Mars. The collision shredded the planet’s northern hemisphere and left massive deposits of metallic elements, and the debris it left in its wake was eventually shaped into Martian moons Phobos and Deimos. Phobos is thought to be on a collision course with Mars itself in several million years.

This Martian meteorite sample contains traces of the rare metal iridium.

After examining samples of meteorites that had hit Earth, Mojzsis and Brasser noted the rare metal content (think elements like iridium, osmium, and platinum) significantly exceeded their expectations. Such asteroids have pummeled Mars numerous times, which led to the estimate that its rare metal content accounts for about 0.8% of its mass. That doesn’t sound like much until you realize the mass of Mars is a staggering 1.409 lb x 10 to the 24th power. Now just try to fathom how much metal is in eight thousandths of that.

When the scientists simulated asteroid collisions to approximate the size of the celestial beast that bashed Mars, they found it to be gargantuan. Imagine something 745 miles across (around the length of California) body-slamming Mars 4.43 billion years ago. Mojzsis and Brasser believe that the areas of the planet that were Martian rock and those made of asteroid material were distinguishable in the aftermath of the impact. They were eventually blurred together by wind and erosion among other surface phenomena. Asteroids kept coming after that, but nothing so immense.

Mars also has an abundance of siderophile elements (which bond with iron) deep in its mantle. While it isn’t exactly Iron Maiden, that in itself is really metal.

(via Seeker)