From: LARRY KLAES (ljk4_at_msn.com)
Date: Wed Oct 10 2007 - 11:27:46 PDT
>From: "AAS Press Officer Dr. Steve Maran" <Steve.Maran_at_aas.org>
>To: "AAS Press Officer Dr. Steve Maran" <steve.maran_at_aas.org>
>Subject: ESA: Rare Molecule Found on Venus - Could Add to Greenhouse Effect
>Date: Wed, 10 Oct 2007 13:51:12 -0400
>
THE FOLLOWING RELEASE WAS RECEIVED FROM THE EUROPEAN SPACE AGENCY'S "ESA WEB
PORTAL - SCIENCE," IN NOORDWIJK, THE NETHERLANDS AND IS FORWARDED FOR YOUR
INFORMATION. Steve Maran, American Astronomical Society
steve.maran_at_aas.org 1-202-328-2010 x116
Contact information at the end of the release.
Article and images can be found at:
http://www.esa.int/esaSC/SEMF8BV7D7F_index_0.html
10 October 2007
New isotope molecule may add to Venus' greenhouse effect
Planetary scientists on both sides of the Atlantic have tracked down a rare
molecule in the atmospheres of both Mars and Venus. The molecule, an exotic
form of carbon dioxide, could affect the way the greenhouse mechanism works
on Venus.
The discovery is being announced today at the annual meeting of the American
Astronomical Society's Division of Planetary Sciences in Orlando, Florida.
Its presence could affect the way the greenhouse mechanism works on Venus.
The mystery began back in April 2006, soon after ESA's Venus Express arrived
at the second planet in the Solar System.
A European team including members from France, Belgium and Russia lead by
Jean-Loup Bertaux, Service d'Aeronomie du CNRS, France and Ann-Carine
Vandaele, Institut d'Aeronomie Spatiale de Belgique, were using their
Infrared Atmospheric Spectrometer (SOIR) instrument to measure solar
occultations.
To do this, the instrument watches the Sun set behind Venus, allowing the
scientists to study the way specific wavelengths of light are absorbed by
the planet's atmosphere. These wavelengths and the level of absorption then
give away the identity and amount of gases in the atmosphere.
The team saw an unidentified signature at 3.3 micrometres in the
mid-infrared region of the spectrum. "It was conspicuous and systematic,
increasing with depth in the atmosphere during the occultation, so we knew
it was real," says Bertaux.
The team kept their discovery confidential as they attempted to identify the
molecule responsible. They thought at first that it must be an organic
molecule. These molecules contain carbon and hydrogen. However, none of the
known organic molecules fitted well with the observations.
Then, in December 2006, Mike Mumma of NASA's Goddard Space Flight Center,
Maryland, enquired whether the SOIR team was seeing anything special on
Venus at 3.3 microns. He had discovered an unidentified spectral signature
at that wavelength using telescopes on Hawaii pointing at Mars. The two
teams compared the absorption signatures: they were identical.
This was a big clue. Both the atmospheres of Mars and Venus are composed of
95% carbon dioxide, although Venus's atmosphere is much thicker than the one
at Mars. The American team suggested that the signature could be coming from
an isotope of carbon dioxide, where one oxygen atom is 'normal', with eight
protons and eight neutrons, while the other has eight protons and ten
neutrons. Such an isotope makes up about 1% of carbon dioxide on Earth, the
rest contains two normal oxygen atoms.
However, no one had previously seen the molecule absorb at 3.3 micrometres.
An investigation by three independent groups, one led by Mumma in America,
Sergei Tashkun and Valery Perevalov at Tomsk State University, Russia, and
Richard Dahoo at Service d'Aeronomie du CNRS, France, all came to the same
conclusion. The signature could be caused by a rare transition only possible
in the isotope.
The different weights of the oxygen atoms allow the molecule to alter its
vibration in two ways simultaneously, whereas normal molecules can only
change one state at a time.
This rare transition allows it to absorb even more energy and so contribute
even more to the greenhouse effect on Venus. On Earth, however, there is 250
000 times less carbon dioxide so its additional contribution to our
greenhouse effect will be small.
Notes for Editors:
The findings appear in: 'First Observation of 628 CO2 isotopologue band at
3.3 micrometres in the atmosphere of Venus by solar occultation from Venus
Express' by J-L Bertaux, A. C. Vandaele, V. Wilquet, F. Montmessin, R.
Dahoo, E. Villard, O. Korablev, A. Fedorova.
For more information:
Jean-Loup Bertaux, Service d'aeronomie du CNRS, France
Email: Jean-Loup.Bertaux_at_aerov.jussieu.fr
Ann Carine Vandaele, The Belgian Institute for Space Aeronomy
Email: A-C.Vandaele_at_aeronomie.be
Michael Mumma, NASA Goddard Space Flight Center, USA
Email: Michael.J.Mumma_at_nasa.gov
ESA PIO source:
Monica Talevi
Science Information Manager
ESA - Communication Dept.
Tel: +31 71 565 3223
Fax: +31 71 565 4101
Email: Monica.Talevi_at_esa.int
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