Venus Express discovers hydroxyl in the atmosphere of Venus through its nightglow emission (15 May 2008)
- Details
- Published on 07 May 2008
A&A press release
Released on May 15th, 2008
|
Venus Express discovers hydroxyl in the atmosphere of Venus through its
nightglow emission |
“First detection of hydroxyl in the atmosphere of
Venus”, by Piccioni et al.
Published in Astronomy & Astrophysics Letters,
2008, vol. 483-3, pp. L29
Using observations from the Venus Express spacecraft,
an international team of astronomers presents the first detection of
hydroxyl (OH) in the atmosphere of Venus through its nightglow
emission. Observing atmospheric airglow is a major tool for inferring
the composition and chemistry of the upper planetary atmospheres. These
results will be published in Astronomy &
Astrophysics.
Astronomy & Astrophysics is publishing the
first detection with the Venus Express spacecraft of hydroxyl (OH) in
the atmosphere of Venus. The OH “radical” is a very
special and reactive molecule, which is unusual in conventional
chemistry because of its reactivity. Using the VIRTIS instrument
onboard Venus Express, an international team of astronomers [1]
observed the light emission from the night side of Venus's atmosphere
and detected the presence of the OH radical in the spectra. The Venus
Express spacecraft has been orbiting Venus for more than two years and
has already provided planetologists with a handful of new results [2].
Just like the Earth, the atmosphere of Venus emits a very weak light
caused by various processes occurring in the upper atmosphere. On
Earth, this weak emission of light, known as airglow, was discovered in
1868. It is also referred to as nightglow because it can only be seen
during the night. In the daytime, it is hidden by the much stronger
light because of sunlight scattering. Observing atmospheric airglow is
a major tool for inferring the composition and chemistry of the upper
atmospheres of planets. For example, in Earth's atmosphere, the airglow
from the OH radical, which was detected in 1948, was later found to
play an important role in purging the atmosphere of pollutants harmful
to the biosphere. Theoretical studies show that the hydroxyl airglow
also plays an important role in the chemistry of Mars' atmosphere, but
it has not yet been detected.
On Venus, airglow emissions have already been observed coming from
nitrogen monoxide (NO) and oxygen dioxide (O2).
The VIRTIS team now reports measurements of four airglow emission
lines: two from OH at 1.44 and 2.80 microns and two from O2 at 1.27 and
1.58 microns. Figure 1 illustrates these detections. Except for the O2
emission line at 1.27 micron, which has already been observed on Venus,
all three of the other emission lines have never been observed before,
neither on Venus nor on another planet besides Earth [3].
These new observations are the most direct information found yet of
three key components of Venus's upper atmosphere: hydrogen, hydroxyl,
ozone (O3), and possibly perhydroxyl (HO2).
Fig. 1 - Nightglow
emission from OH and O2 in the atmosphere of
Venus. The
spectrum shows
the emission lines from OH (at 1.44 and 2.80 microns) and from O2
(at
1.27 and 1.58 microns). Except for one of the O2
emission lines, all
three other features have never been observed before on another planet
besides the Earth.
[1] The team of astronomers includes G. Piccioni, A. Migliorini, V. Cottini (INAF-IASF, Roma, Italy), P. Drossart, S. Erard (LESIA, Observatoire de Paris, CNRS, France), L. Zasova, A. Shakun, N. Ignatiev (IKI, Russia), J-C Gérard (LPAP, Liège, Belgium), F.P. Mills, A. Garcia Munoz (Australian National Univ.), D. Grassi, (INAF-IFSI, Roma, Italy), F.W. Taylor (Oxford Univ., UK), and the VIRTIS-Venus Express Technical Team.
[2] Visit the Venus Express web site.
[3] While never detected before on another planet besides Earth, hydroxyl is frequently observed in the atmosphere of comets.
First detection of hydroxyl in the atmosphere of Venus, by G. Piccioni, P. Drossart, L. Zasova, A. Migliorini, J-C Gérard, F.P. Mills, A. Shakun, A. Garcia Munoz, N. Ignatiev, D. Grassi, V. Cottini, F.W. Taylor, S. Erard, and the VIRTIS-Venus Express Technical Team.
Astronomy & Astrophysics Letters, 2008, volume 483-3, pp. L29. Full article available in PDF format
Contacts:
- Science:
Dr.
Giuseppe Piccioni
IASF-INAF
via del Fosso del Cavaliere 100
00133 Roma, Italy
Email: giuseppe.piccioni (at) iasf-roma.inaf.it
Phone: +39 064 9934445 (4547) / +39 335 7270347
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Dr.
Jennifer Martin
Journal Astronomy & Astrophysics
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75014 Paris, France
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© Astronomy & Astrophysics 2008