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The Engineer
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Astro-Spectroscopy

10/13/2007 4:07 PM

Here is an interesting article that serves as an example of the quickly growing field of Astro-Spectroscopy.

Strange Molecule Found in Venus's Atmosphere

A strange gaseous molecule has been discovered lurking in the atmospheres of both Mars and Venus, scientists announced today, adding that it could affect Venus's hyperactive greenhouse effect.

The molecule's signature was first noticed in Venus's atmosphere in April 2006, when the European Space Agency's Venus Express arrived at the planet and began to measure the composition of the atmosphere.

The Infrared Atmospheric Spectrometer instrument aboard the spacecraft watched the sun set behind the planet and measured the wavelengths of light absorbed by the planet's atmosphere. Because different gases absorb at different wavelengths, scientists can infer the composition of the atmosphere from the wavelengths that are strongly absorbed.

While observing Venus, scientists noted an unusual signature in the mid-infrared region of the spectrum that they couldn't identify.

"It was conspicuous and systematic, increasing with depth in the atmosphere during the occultation, so we knew it was real," said study leader Jean-Loup Bertaux of the Service d'aeronomie of France's National Center for Scientific Research (CNRS).

Later that year, NASA scientists observing Mars using telescopes in Hawaii notified Bertaux's team that they had found the same unusual signature.

Because the atmospheres of both Mars and Venus are composed of 95 percent carbon dioxide (as compared to Earth's atmosphere which has only 0.04 percent carbon dioxide and is composed primarily of nitrogen), the researchers thought the strange molecule could be an isotope of carbon dioxide. (Isotopes have the same number of protons, but a different number of neutrons than the main form of an element.)

This exotic form of carbon dioxide has one "normal" oxygen attached to its carbon atom, while the other attached oxygen atom has 10 neutrons, instead of the usual eight.

The differently-weighted oxygen atoms let the isotope absorb more energy than normal carbon dioxide molecules, which could mean that it contributes more to the greenhouse effect on stifling-hot Venus, the researchers said.

http://news.yahoo.com/s/space/20071013/sc_space/strangemoleculefoundinvenussatmosphere

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Guru
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#1

Re: Astro-Spectroscopy

10/14/2007 5:18 AM

Hi Roger. Interesting!

Is it known whether that "strange gaseous molecule" also appears in Earth's atmosphere?

Jorrie

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Guru

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#2
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Re: Astro-Spectroscopy

10/14/2007 8:55 PM

It would make some probability sense, at least in the past (before Earth was terraformed), since Earth is situated between the two (Venus and Mars), and all were created together

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The Engineer
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#6
In reply to #1

Re: Astro-Spectroscopy

10/15/2007 9:27 AM

Jorrie,

It may, but because our concentration of CO2 is so much lower and there is a lot of noise in the spectrum (O2, N2, CH4, etc.) so it's not easily detected. In other words, I don't believe there is any special mechanism creating this isotope molecule, I just think its much easier to identify in a spectrum that is pretty much all CO2.

Roger

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#3

Re: Astro-Spectroscopy

10/14/2007 8:58 PM

Interesting!! Is the surface temperature on Mars also relatively as stifling as that of Venus? If both have atmospheric CO2 contents of ~95% and this molecule is an isotope of carbon dioxide, then Mars should conceivably show a relatively high level of global warming like Venus.

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Guru
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#4
In reply to #3

Re: Astro-Spectroscopy

10/15/2007 8:28 AM

No. The temperatures on the surface of Mars is much colder than on Venus. One reason is the extreme density of Venus' atmosphere, coupled with it's relative nearness to the Sun. Mars has a relatively low density atmosphere.

If I remember correctly, Venus also has a lot of sulfuric acid vapors present, which could attack any limestone (etc) formations, generating even more carbon dioxide.

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The Engineer
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#5
In reply to #3

Re: Astro-Spectroscopy

10/15/2007 8:58 AM

Mars has much less atmosphere and so the atomosphere in general is very very thin, it is roughly 1/100th the surface pressure of Earth. In addition, Mars is much further from the sun so the power on the ground due to the sun is much much less (590 W/m2 maximum). So no, its not very warm there.

http://www.daviddarling.info/encyclopedia/M/Marsatmos.html

http://www.tomatosphere.org/EngManual/mars_agri.html

Venus on the other hand is .72 AU from the sun and has a mean surface temperature of 735K as compared to Mercury that is .46 AU from the sun and has a maximum surface temperature of 700K. In other words, Mercury is 36% closer to the sun and receives 3x the intensity from the Sun than Venus does yet is COOLER. That's what CO2 in an atmosphere can do.

http://en.wikipedia.org/wiki/Mercury_(planet)

http://en.wikipedia.org/wiki/Venus

http://www.starhop.com/High/SolInt-19.pdf

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