04-September-2008, 06:34 PM
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Order of Kilopi
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Join Date: Mar 2004
Posts: 13,461
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Quote:
Originally Posted by Ivan Viehoff
The simplest inorganic explanation for this is that the soil contained a vigorous oxidising agent. So when I heard they had found perchlorate, I wasn't in the least surprised. But I'm simplifying, I think it is more controversial than that.
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NASA Phoenix Mission: Audio Briefing, August 5
Quote:
Eric Hand:
Hi. Yeah. I was hoping you could put this in the context of previous probes. I think someone else asked this question. But, maybe you could describe how this perchlorate finding is different from what Viking found.
They didn't find this. There's been a lot of debate over what the oxidizer was that Viking found. A lot of folks thought it was hydrogen peroxide. Does this suggest that perchlorate is the main oxidizer on Mars. How does this relate to what Viking found?
Richard Quinn:
This is Richard Quinn speaking. You're absolutely right about the statement of Viking. The leading hypothesis for what was seen in the Viking biology experiments was the presence of small amounts of peroxide or superoxide. For those who are not familiar with it, it was the light detection experiment.
What they saw was, when they wetted the soil, they saw a small amount of oxygen released. They saw some decomposition of some of the organic nutrients that they brought with them. Perchlorate is very different. Perchlorate is typically not very reactive in solution.
It would not typically give off oxygen when wetted. So the perchlorate is not likely, in my opinion, it is not responsible for the Viking biology experiment. It's not the same compound. But, I do think that it all does point to a very interesting photochemistry that I mentioned earlier.
The hypothesis with Viking is that the small amounts of peroxide were also produced in the atmosphere photochemically and then deposited down on the surface. So again, yeah, I think that there will be some very interesting ties in the future to these types of compounds, how they interact with water and how they move through soils and what the implications are there.
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