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#1 Crisp



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Posted 21 October 2013 - 23:51

Mars Curiosity rover proves some meteorites on Earth are Martian



The rear of the stone from the Tissint Martian meteorite is almost completely covered with a glossy black fusion crust.


Some pieces of rock that fell to Earth from space are indeed from Mars, new measurements reveal.

Readings collected by NASA's Mars rover Curiosity have pinned down the exact ratio of two forms of the inert gas argon in the Martian atmosphere. These new measurements will not only help confirm the origins of some meteorites, they could also help researchers understand how and when Mars lost most of its atmosphere, transforming from a warm, wet planet to the red desert it is today.

By understanding exactly how much of the lighter isotope argon-36 is present in the Martian atmosphere and comparing it to the heavier isotope, argon-38, scientists were able to confirm what the composition of a Martian meteorite on Earth should be.

"We really nailed it," Sushil Atreya of the University of Michigan, lead author of a paper reporting the finding in Geophysical Research Letters, said in a statement. "This direct reading from Mars settles the case with all Martian meteorites."

Curiosity found that the ratio of argon-36 to argon-38 for Mars is 4.2 to 1. The lighter form of argon has escaped more readily than the heavier isotope, NASA officials wrote in a statement.

If Mars had not lost atmosphere through the course of its planetary history, its argon ratio would be 5.5 — the same as the sun and Jupiter, two cosmic bodies with so much gravity that isotopes cannot escape, NASA officials said.


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#2 DocM


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Posted 22 October 2013 - 00:21

Never had any doubt.

#3 Growled


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Posted 22 October 2013 - 01:27

I never have really understood how Martian rocks could make it here? I would have thought gravity would keep them there.

#4 DocM


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Posted 22 October 2013 - 02:17

Meteorite and comet strikes can eject rocks with escape velocity, so getting them off a planet isn't a problem. After that they drift until Earth gets in the way. There are meteorite classes that are pieces knocked off Vesta (howardite, eucrite and diogenite), and the pallasites are thought to be a fusion of core & mantle bits from larger asteroids that were shattered.

#5 Enron


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Posted 22 October 2013 - 02:34

Do we have any meteorites from other planets?

#6 DocM


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Posted 22 October 2013 - 02:45

Mars, Moon and Vesta meteorites have been identified, and in principle Mercury and Venus are possible but as yet not found. Not many are likely from Mercury and Venus because they're deeper in the Sun's gravity well.

Now let his bake your noodles; it's very likely there are chunks of Earth on other planets etc. because we've been hit too.