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SvenTropics t1_j1a36fs wrote

Uh, why is it red then? I was under the impression that the iron rich surface had oxidized to give it that color.

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CommunicationFun7973 t1_j1a7enr wrote

Where do you think the little oxygen that Mars got from space/internal processes went? After a few billion years even a tiny amount will cause that.

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SvenTropics t1_j1a9m7k wrote

Well, the question is where did it come from? Oxygen is highly reactive, even in space. We also know that mars had a liquid ocean and a magnetic field once upon a time. Earth was like this too with almost no oxygen in the atmosphere for millions of years. During that time, life was evolving. Eventually some microorganism evolved photosynthesis and proliferated rapidly with seemingly limitless energy, abundant CO2 and no competition. This caused a massive swing in a geologically short period of time from nearly no oxygen in the atmosphere to oxygen being very plentiful as it was essentially a waste product of the process.

The high reactivity of Oxygen made it toxic to nearly all life on earth causing a mass extinction of most organisms. The ones that evolved to tolerate it survived.

On Mars, there's no proof that such a process happened, but I think it did. I believe photosynthetic life existed on there for millions of years. After it all died off, the oxygen gradually reacted with the surface and carbon in the air until O2 levels were mostly gone.

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patricksaurus t1_j1akmsm wrote

Oxygen is the most abundant element in Earth’s crust. It’s the third most abundant element in the universe. The null hypothesis of abiotic iron oxides has to be rejected before you speculate about life on Mars based on iron oxide mineralogy.

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EmperorHans t1_j1c5kdv wrote

Man, I had a wildly misinformed idea of what's in earths crust. I just looked up the top ten, and that list looks nothing like I wouldve guessed.

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patricksaurus t1_j1c8u4n wrote

Oh this is an interesting comment for me. Do you mind telling me what you expected? Not strictly as a list, just sorta what you thought and maybe why? I’m always curious about this kind of thing.

For instance, I expected a more hydrogen, just because of its abundance in the universe.

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SvenTropics t1_j1anb94 wrote

"Molecules containing Oxygen". O2 is wildly reactive. It doesn't stick around long.

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Fyrefawx t1_j1av893 wrote

I’ll never get over the fact that oxygen caused an extinction at one point and now nearly everything requires it to survive.

It’s so wild how life was able to change the the planet itself long before humanity arrived.

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SvenTropics t1_j1d0el0 wrote

I mean if life somehow evolved to survive in sulfuric acid, it would grow to require it.

On one hand, oxidation is deadly to organisms. On the other hand, the reactiveness of it is a great resource for generating energy.

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CommunicationFun7973 t1_j1aaesn wrote

Yes, oxygen is highly reactive. Tends to react with iron pretty often in the universe, often being either metal oxides or water. Geological processes can transfer oxygen too without it being in elemental form.

So to answer your question, it came from space, likely reacted in space then came down from asteroids. So this iron was likely like this before Mars came to be. But also the very surface over billions of years WILL come into contact with elemental oxygen in space.

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Lithgow_Panther t1_j1afhxh wrote

Why do you believe that?

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SvenTropics t1_j1an5v9 wrote

It seems like the most intuitive source for all the oxidation on the planet.

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Lithgow_Panther t1_j1as6l4 wrote

Abiogenesis + evolution of photosynthesis is more intuitive than, say, water ionisation and molecular oxygen formation?

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Underhill42 t1_j1f8p4o wrote

On Earth it took something like a billion years after photosynthesis evolved before there was any more than trace amounts of oxygen in the atmosphere - oxidation stripped it out of the atmosphere just as fast as it was produced, until there was nothing left to oxidize.

Meanwhile, as others have said, oxygen is one of the most abundant elements in the universe, and makes up a huge percentage of the mass of all rocky planets (ballpark of 40% based on available samples) , it's very possible that Mars was well and truly oxidized just as soon as the surface cooled down enough for stable oxides to exist. Heck, the proto-planetary cloud that eventually became Mars was almost certainly already incredibly rich with oxides long before the planet formed - but the heat of formation would have driven off the oxygen from all but the most stable oxides until temperatures cooled again.

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zoicyte t1_j1agtfe wrote

You’re absolutely right; that’s why there isn’t any oxygen in the atmosphere basically. Among other reasons; oxygen is one of those molecules that doesn’t stick around unless there’s a source.

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PunkySputnik57 t1_j1a3pq2 wrote

Same. I was always told the rocks were red because of rust

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JoCoMoBo t1_j1acxaq wrote

>Same. I was always told the rocks were red because of rust

Incorrect. Just like the Moon is made of cheese, Mars is made out of discarded red lipsticks. This is why it is red.

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LudeStreetwalker t1_j1aqnxf wrote

Don't be stupid, the moon is cheese and Mars is a spice planet covered in Cajun, cayenne, paprika, etc. Everyone knows that.

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JoCoMoBo t1_j1aux75 wrote

That’s just ridiculous. Cajun and paprika wouldn’t go together like that..

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Underhill42 t1_j1f9o4g wrote

That's why Earth evolved life - to keep its spices properly separated. Not every planet is that clever.

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sirbruce t1_j1b0eo2 wrote

If you read the article, the answer is iron (and all the other elements) did indeed oxidize, but with water, not with free oxygen in the atmosphere. At least, that's what the experiment says could have happened. The reason for this is chlorates and bromates in the water that enable this reaction, at least in the case of manganese. Whether or not this applies to iron I don't know. What is important is that manganese doesn't turn into manganese oxide when there is oxygen in the air if you also have too much CO2, so unless your model has the Martian atmosphere "just right" to make manganese oxide, you need an alternative process.

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Albert_VDS t1_j1a7xif wrote

Yes, there is no other way. If it did have much oxygen then it would be called Mars the rockish planet.

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