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Venus Express press conference November 28th, Venus: a more Earth-like planetary neighbour
belleraphon1
post Nov 20 2007, 12:27 PM
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All..

Venus Express press conference set for November 28th.

http://www.esa.int/esaCP/SEMX1C63R8F_index_0.html

‘Venus: a more Earth-like planetary neighbour’
Latest results from Venus Express
28 November 2007, 15:00, room 137
ESA Headquarters, 8-10 rue Mario-Nikis, Paris

15:00 Introduction, by Håkan Svedhem, ESA Venus Express Project Scientist
15:07 Venus: What we knew before, by Fred Taylor, Venus Express Interdisciplinary Scientist

15:15 Temperatures in the atmosphere of Venus, by Jean-Loup Bertaux, SPICAV Principal Investigator

15:25 The dynamic atmosphere of Venus, by Giuseppe Piccioni, VIRTIS Principal Investigator

15:40 Venus’s atmosphere and the solar wind, by Stas Barabash, ASPERA Principal Investigator

15:50 Climate and evolution, by David Grinspoon, Venus Express Interdisciplinary Scientist

16:00 Conclusion, by Dmitri Titov, Venus Express Science Coordinator and VMC scientist

16:05 Questions and Answers

16:25 Individual interviews

17:30 End of event

Craig
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Julius
post Nov 30 2007, 11:57 AM
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I am no planetary sceintist but just a humble enthusiast!I have a few queries maybe some of you could answer:

Why should Venus have a thicker atmosphere than Earth provided it lacks a magnetic field and hence being in direct contact with the solar wind ,which should produce higher rates of atmospheric loss.This seems to be the explanation for mars!?

The moon is said to be acting as a friction brake on Earths rotation and thus is slowing it down.Has anyone explained clearly why Venus is such a slow rotator in the absence of a moon!Could a previous collision of a cosmic body with Venus help to explain this . Venus was once(i think its about 500-800 million years ago) entirely resurfaced by hot magma .Could this have happened when this theorised collision took place?

Why should Venus lack a magnetic field given its the same radius and almost same density like Earth?Could it be that its dry compared to Earth ,simply explain for this significant difference?
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hendric
post Nov 30 2007, 05:37 PM
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QUOTE (Julius @ Nov 30 2007, 05:57 AM) *
I am no planetary sceintist but just a humble enthusiast!I have a few queries maybe some of you could answer:

Why should Venus have a thicker atmosphere than Earth provided it lacks a magnetic field and hence being in direct contact with the solar wind ,which should produce higher rates of atmospheric loss.This seems to be the explanation for mars!?

The moon is said to be acting as a friction brake on Earths rotation and thus is slowing it down.Has anyone explained clearly why Venus is such a slow rotator in the absence of a moon!Could a previous collision of a cosmic body with Venus help to explain this . Venus was once(i think its about 500-800 million years ago) entirely resurfaced by hot magma .Could this have happened when this theorised collision took place?

Why should Venus lack a magnetic field given its the same radius and almost same density like Earth?Could it be that its dry compared to Earth ,simply explain for this significant difference?



My knowledge is fairly basic, but here is how I understand it.

Most, if not all, of your questions center around water. Venus had, presumable, similar amounts to Earth, but lost it. Initially it was probably in oceans. These dried up due to the heat as the Sun warmed. Water is a much better greenhouse gas than CO2, so it increased the temperature even more. As the atmosphere got saturated with water, more and more of the water was photodissociated to hydrogren and oxygen by the UV from the sun. The hydrogen escaped, leaving the oxygen. Over time, most of the water disappeared.

As the climate heated up, the rocks themselves lost their water and CO2. On earth, there is a great quantity on CO2 stored in rocks as carbonates etc. So even though there is more loss due to solar wind at Venus, there is just so much more atmosphere because all the stored CO2 has been released. Plus, Venus gravity is much higher than Mars. Also, for Mars there is a theory that oblique asteroid impacts "threw" parts of the atmosphere off of the planet.

As for the slow rotation, there are multiple theories there. The one I've heard is that the atmosphere itself could have cause the rotation to slow down and switch directions over eons, with solar tides playing a big factor. A previous collision is also possible, but would be hard to prove without evidence (like a Moon! smile.gif ).


The resurfacing is, again, related to the lack of water. The current theory is that without water, the crust is less flexible, and much thicker. Because of that, the heat generated internally builds up to high temperatures before it gets hot enough to escape to the surface. When it does, I imagine Venus, under the atmosphere, would be covered with as many volcanoes as Io.

The lack of a detectable magnetic field is due to the lack of rotation. Assuming a similar composition to Earth, it would have a molten core with the appropriate convection currents. But because the planet doesn't rotate very fast, it cannot generate a magnetic field using a dynamo effect. How I visualize the internal dynamos is to think of spider silk floating in the air (these are the magnetic field lines). Imagine grabbing it with your hand, and start spinning your hand until it's covered in the silk. The closer the silk is to itself, the stronger the field lines. In the core the field lines are close, since the conductive molten iron grabs the lines tighter than the nonconductive rest of the earth. Because Venus doesn't spin very fast, it doesn't "catch" enough field lines to make a significant magnetic field. It's probable it does generate a very small magnetic field, just that it's too weak to get very far from the core.


I'm sure Emily can give us the straight answer on all these, being the Venus expert she is! smile.gif


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Space Enthusiast Richard Hendricks
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"The engineers, as usual, made a tremendous fuss. Again as usual, they did the job in half the time they had dismissed as being absolutely impossible." --Rescue Party, Arthur C Clarke
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Posts in this topic
- belleraphon1   Venus Express press conference November 28th   Nov 20 2007, 12:27 PM
- - belleraphon1   Also... The results will appear in a special sec...   Nov 20 2007, 12:29 PM
- - cndwrld   Press Conference Results The press conference res...   Nov 28 2007, 08:07 PM
- - nprev   To say nothing of Venus' past. It looks as if ...   Nov 29 2007, 12:59 AM
- - Zvezdichko   Venus Express is not the first spacecraft to detec...   Nov 29 2007, 02:45 PM
|- - tedstryk   There was always controversy surrounding that. No...   Nov 29 2007, 03:08 PM
|- - JRehling   QUOTE (tedstryk @ Nov 29 2007, 07:08 AM) ...   Nov 29 2007, 07:30 PM
|- - JRehling   QUOTE (JRehling @ Nov 29 2007, 11:30 AM) ...   Nov 30 2007, 05:43 PM
- - edstrick   CT Russell is one of the partisan participants in ...   Nov 30 2007, 11:38 AM
- - Julius   I am no planetary sceintist but just a humble enth...   Nov 30 2007, 11:57 AM
|- - JRehling   QUOTE (Julius @ Nov 30 2007, 03:57 AM) I ...   Nov 30 2007, 05:20 PM
||- - Juramike   QUOTE (JRehling @ Nov 30 2007, 12:20 PM) ...   Nov 30 2007, 06:15 PM
|- - hendric   QUOTE (Julius @ Nov 30 2007, 05:57 AM) I ...   Nov 30 2007, 05:37 PM
|- - elakdawalla   QUOTE (hendric @ Nov 30 2007, 09:37 AM) I...   Nov 30 2007, 06:31 PM
- - nprev   Let's not forget that there's a poorly und...   Nov 30 2007, 06:28 PM
- - hendric   QUOTE (Juramike @ Nov 30 2007, 12:15 PM) ...   Nov 30 2007, 07:44 PM
|- - Juramike   QUOTE (hendric @ Nov 30 2007, 02:44 PM) H...   Nov 30 2007, 08:03 PM
||- - Julius   QUOTE (Juramike @ Nov 30 2007, 09:03 PM) ...   Nov 30 2007, 09:26 PM
||- - vjkane   As I remember, one of the puzzles of planetary sci...   Dec 1 2007, 12:30 AM
||- - JRehling   QUOTE (vjkane @ Nov 30 2007, 04:30 PM) As...   Dec 1 2007, 01:00 AM
||- - mcaplinger   QUOTE (JRehling @ Nov 30 2007, 05:00 PM) ...   Dec 1 2007, 02:33 AM
||- - Tom Tamlyn   So also is the existence of a large moon (product ...   Dec 1 2007, 02:38 AM
||- - brellis   The other day, I found a copy of David Grinspoon...   Dec 1 2007, 06:11 AM
||- - JRehling   QUOTE (brellis @ Nov 30 2007, 10:11 PM) T...   Dec 1 2007, 08:08 AM
|- - AndyG   QUOTE (hendric @ Nov 30 2007, 07:44 PM) ....   Dec 1 2007, 02:00 PM
|- - JRehling   QUOTE (AndyG @ Dec 1 2007, 06:00 AM) Woul...   Dec 1 2007, 04:30 PM
- - edstrick   Regarding the lack of magnetic field... 1) Venus ...   Dec 1 2007, 10:26 AM


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