Venus Express Options

[ngunn]

Thanks Mike, that gives useful insight on the first Q. (The second Q was really more about the mechanism of water loss than the water-with-O18 IR spectrum itself, but your reply was interesting anyway.)

Found this through Google - heavy water isn't blue!

http://images.google.com/imgres?imgurl=htt...sa%3DN%26um%3D1

[Juramike]

Found this through Google - heavy water isn't blue!

http://images.google.com/imgres?imgurl=htt...sa%3DN%26um%3D1

That is a very cool link!

[Juramike]

That is a very cool link!

OT, but I poking through that link I found this "gem" on Triboluminescence.

I spent last evening rubbing two quartz pieces I found in our yard together to make them glow.
(Giggling like a little kid the whole time..wheee!!!!)

[Paolo]

OT, but I poking through that link I found this "gem" on Triboluminescence.

ever tried crushing a sugarcube in the dark? Try and you will be amazed

[djellison]

Open an envelope, crack a mint in half. Same thing.

[Greg Hullender]

Maybe we need a "Science Experiments" thread. :-)

--Greg

[ngunn]

Well, having swept up the sugar in the broom cupboard I'm still trying to find more answers to the questions I posed in post 344 about the asymmetric form of heavy water and water with heavy oxygen. I found another very helpful link, given below, where both are briefly described. HDO seems to have at least three names: hydrogen deuterium oxide, hydrogen protium oxide and semiheavy water. Apparently H and D exchange easily between molecules so the relative abundances of H2O, D2O and HDO are in equilibrium in any given environment with absolute amounts determined by the overall H:D ratio. I think this means that where there is much less D than H there will be much more HDO than D2O. (The link in my 'heavy water isn't blue' post was all abour D2O.)

As to whether the asymmetry of HDO results in spectral properties of significance to planetary science I am still none the wiser.

http://wapedia.mobi/en/Heavy_water

[Juramike]

H and D (and T) will exchange among depending on the acidity function (pKa) of the protons. Acidic protons exchange. Water or methanol terminal protons are acidic. So if you start with CH3OH and put it in with a lot of D2O you will end up with CH3OD, D2O, some HDO, very little CH3OH and probably a few molecules of H2O.

(Chemists use deuterated solvents all the time to aquire 1H NMR spectra, the D signal acts is used to "lock" the magnetic field. Exchangeable protons usually disappear and are not visible or diminished in the 1H NMR spectrum. Likewise, the deuterated solvent always shows a residual peak due to some proton exchanging in, that can also be used to reference the 1H NMR spectrum.)


For IR spectra, here is an available reference for the region 8100-7600 cm-1 (1.23-1.32 um): http://staff.ustc.edu.cn/~smhu/publication...203_HDO_300.pdf

Here is a reference (I couldn't get it) for the region 700 nm to 10,000 nm (=10 um) http://adsabs.harvard.edu/abs/1963InfPh...3..211B


Here is also a reference that shows that comets have a different H/D ratio than on Earth. (Thus Earth's water might've been intrinsic.):
http://www.sciencemag.org/cgi/content/abstract/279/5352/842

[ngunn]

Thanks for those links! I've printed off the first one and the abstract of the comets one, but like you couldn't get the second one at all - a pity since it covers a wide spectral range highly relevant to the study of planetary atmospheres. Not being a specialist in all this I will continue to look for an 'easier' overview, but I suspect I may be out of luck. I think a rummage through a few good hefty textbooks is what's required, but our college library doesn't run to such.

[Juramike]

Whoops! My bad! Here is a link to the 0.7-10 um region article is available with paid-for access.

Bayly et al. Infrared Physics, 1963 3, 211-223. "Absorption spectra of liquid phase H2O, HDO, and D2O from 0.7 um to 10 um."

The article shows the full spectrum for H2O and D2O, with an estimated spectrum for HDO, along with (technical) explanations of the assymmetry of HDO and how it would affect the spectrum.

It also highlights the areas where there are big differences between the absorbances of H2O and HDO.
HDO has a big extinction coefficient at 4 um, while H2O has a big extinction coefficient around 3 um.

(The spectra for H2O and D2O look like the spectra you showed from the article, there are just more details regarding exact shifts, extinction coefficients, and vibrational mode assignments.)

-Mike

[ngunn]

Thanks again Mike. That's obviously the one I need to track down when I get the chance. Your summary is most useful (more so than the abstract for my purposes, as you mention that the effects of asymmetry are specifically discussed).

[cndwrld]

The Science Programme Committee (SPC) of the European Space Agency (ESA) met on 02 October, and approved the mission extensions for Venus Express and Mars Express through the end of 2012. More details, and all the other missions affected, should be reported soon.

[cndwrld]

Mission Extension News from: http://sci.esa.int/science-e/www/object/in...fobjectid=45685

ESA's Science Programme Committee has approved the extension of mission operations for XMM-Newton, INTEGRAL, Venus Express, Mars Express and Cluster, as well as the ESA support to the operations of HST and SOHO, until 31 December 2012. An additional year of operations has been approved for Planck.

At the 126th meeting of the Science Programme Committee, held 2 October 2009, at ESTEC, the Netherlands, the decision was taken to approve the period of mission operations for seven missions until end 2012. This meeting marked the first application of a new procedure whereby mission extensions for all missions whose approved operations end within the following four years are considered as a whole.

The missions under consideration at this meeting were: XMM-Newton, INTEGRAL, Venus Express, Mars Express and Cluster, and the ESA support to the operations of HST and SOHO. The case for extending the period of operations for these missions is based on the value of the science added as a result of extended operations. The proposal for extension of mission operations for all of these missions, based on recommendations from an SPC Task Group and the Space Science Advisory Committee (SSAC), was accepted by the SPC.

The extensions for mission operations are approved up to 31 December 2012, subject to a mid-term review in 2010. Towards the end of 2010 the SPC will be requested to confirm, subject to the satisfactory performance of the missions, the remaining two years of the extension and to consider further extensions of operations.

The additional year of Planck operations, to follow on from the end of nominal operations in 2010, would facilitate an additional two sky surveys. This extra period of operations is subject to the SSAC confirming that the mission has achieved satisfactory in-orbit performance. Planck, launched in May 2009, has recently commenced routine operations following the successful completion of the in-orbit commissioning and performance verification phases.

The nominal mission operations for Herschel, which was launched with Planck in May 2009, were previously approved until end 2012.

[cndwrld]

The 6th release of the Venus Monitoring Camera (VMC) data for the extended mission is available on the ESA Planetary Science Archive (PSA) at
http://www.rssd.esa.int/index.php?project=PSA.

You will be able to see products up to orbit 1079, which was 04 April 2009.

[Julius]

Did I miss something but could anyone find me a news source from ESA stating that Venus express did find evidence suggestive of recent and ongoing volcanism??