Iron Oxide on Mars

If Mars has all that rust, where did the oxygen come from? We call Mars the “Red Planet” because it has iron oxide – LOTS of it. Where did it come from? Scientists believe both Earth and Mars got most of its surface iron oxides from meteor bombardment about 4 billion years ago. Why does Mars have so much more of it?

BBC has done interesting documentaries on stromatolites, large living bacterial beach “rock” formations we can still see and investigate in Australia. According to this theory, these cyanobacteria use a primitive photosynthesis to generate Earth’s earliest oxygen. This started oxidizing particulate meteorite iron dust suspended in the oceans, converting it to rust, which settled to the ocean bed and was sequestered there. When free iron particles were essentially used up, oxygen could then start accumulating in our atmosphere … paving the way for higher Earth life forms.

Mars seems once to have had copious water. Could it have also had cyanobacteria? Is that how Mars got all its iron oxide?

Well, according to another theory I found on, Martian oceans simply rusted all that meteoric iron away. Of course, if this is the full explanation, we don’t need the stromatolite theory at all to account for iron oxides on either planet.

I found a third theory on BioEd Online. It suggests the answer is not that simple. Researchers have been able to show that Earth’s powerful gravitational field generates enough pressure and heat to melt iron oxide, in effect smelting oxygen out of it, and allowing it to sink into the molten core. Theoretical calculations show smaller Mars could not have generated the required compressional pressures. This would account for Earth’s huge liquid iron core and the powerful dynamo generating our planet’s magnetic field, in turn protecting our atmosphere from the solar radiation that we expect blasted most of the unprotected Martian atmosphere away.

If all goes well, our new robotic explorer Curiosity will safely descend to the Martian surface at 1:31 a.m. Monday Aug. 6 EDT (0531 GMT) – about 10:30PM Sunday night, Pacific time. Facebook has a Curiosity page, and NASA/JPL will have a “live” feed on UStream’s Curiosity Cam. Curiosity will not broadcast photos until it finishes all its own internal checks. The first photos will be black and white, with color plates following on later transmissions.  Remember, there’s currently a 14 minute radio signal delay between Mars and Earth.

I plan to try to stay up to see if the mission is successful. As for our iron oxide questions, it often turns out in science there is not just one “right” contributory answer. It will be interesting to see what mysteries Curiosity can solve.

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