Author Topic: Episode 155 - Less is More  (Read 2060 times)

Offline Daneel

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Episode 155 - Less is More
« on: November 02, 2012, 11:01:33 AM »
Very interesting story about Xenon. I was thinking of posting about the whole heavy-isotope-enrichment and then Patrick said it for me.
It's quite interesting. By analysing the relative abundances of Xenon stable isotopes we know that the earl Earth had a primordial atmosphere that then was lost into space by hydrodynamic scape. Take a look at this graph:


It shows the relative abundance of Xenon isotopes measured on asteroids with respect of the Earth's. You can see that we have much fewer light isotopes and a lot more of the heavy stuff. Mars has a similar problem, although it's actually more enriched with heavy isotopes.

I had to read about this for a report at uni about the origins and evolution of the atmosphere. A very useful resource is the Encyclopedia of Atmospheric Sciences. Here's the chapter which I took the graph from.

Offline Daneel

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Re: Episode 155 - Less is More
« Reply #1 on: November 02, 2012, 12:28:16 PM »
And in an incredible lucky coincidence, today the Curiosity team published their findings that :

Quote
Initial SAM results show an increase of five percent in heavier isotopes of carbon in the atmospheric carbon dioxide compared to estimates of the isotopic ratios present when Mars formed. These enriched ratios of heavier isotopes to lighter ones suggest the top of the atmosphere may have been lost to interplanetary space. Losses at the top of the atmosphere would deplete lighter isotopes. Isotopes of argon also show enrichment of the heavy isotope, matching previous estimates of atmosphere composition derived from studies of Martian meteorites on Earth.

Read more at: http://phys.org/news/2012-11-curiosity-rover-clues-mars-atmosphere.html#jCp