Germany: Mars is rusty due to the small size

13.05.2004

13.05.2004


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Why Mars is much more rusty than the Earth? As you know, in the surface layers of the red planet twice the iron oxide, although, according to experts, both bodies were formed from the same materials. David Ruby and his colleagues at the University of Bayreuth (Germany) claim that they have found the answer: the intensive heat of the early Earth was enough to make much of an iron oxide into iron metal, which has seeped into the planet, forming its giant nucleus. On Mars, as the temperature never reached the required values for the process — simply because Mars is smaller. As a result, the surface remains much more iron oxide, which explains its characteristic rusty color. This also explains the relatively small iron core of the fourth planet.

Ruby developed model showed that both planets were formed from the same material, and then their composition and internal structure gradually changed to the present.

Scientists conducted the experience with hydraulic press to compress the mixture of iron, nickel and oxygen to 175,000 atmospheres at a temperature of 2400 degrees. These experiments helped to determine how to behave iron and oxygen in the early magma ocean planets.

About 4 billion years ago, a young Earth and other terrestrial planets were subjected to intense meteor bombardment. This transformed the surface of the planets in the magma oceans. According to estimates Ruby on Earth depth of the oceans of molten rock reached 1800 kilometers. Below is a solid mantle, and at the bottom — the core of molten iron.

Earth's diameter is almost twice the diameter of Mars, and the mass of the planet more than 10 times. This means that the lower layers of the Earth's magma ocean were much more pressure than on Mars, simply because on top of them weighed more material. On Earth this pressure is raised in temperature to over 3,200 degrees — at a temperature, the iron oxide is easily decomposed into metal iron and oxygen dissolved therein. The liquid iron is then seeped through the magma, creating a relatively large core and leaving in the outer layers of the mantle, only 8% of iron oxide. The process seems to end in the first 30 million years of life on the planet.

Mars in shallower magma ocean temperature hardly rose well above 2,200 degrees. In such a reservoir of iron oxide remained stable. The experiment allowed Ruby to predict that in such circumstances would have remained solid mantle, the iron content of which would be about 18%, which is exactly the same as the iron content in the surface of Mars. This also explains why the Martian core is much smaller mass fraction of the planet than Earth.

Battery News, 12.05.2004 18:51
Source: NTR.ru

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