Where did Venus’s water go?

[n2doc]

18 December 2008
Venus Express has made the first detection of an atmospheric loss process on Venus's day-side. Last year, the spacecraft revealed that most of the lost atmosphere escapes from the night-side. Together, these discoveries bring planetary scientists closer to understanding what happened to the water on Venus, which is suspected to have once been as abundant as on Earth.

The spacecraft's magnetometer instrument (MAG) detected the unmistakable signature of hydrogen gas being stripped from the day-side. “This is a process that was believed to be happening at Venus but this is the first time we measured it,” says Magda Delva, Austrian Academy of Sciences, Graz, who leads the investigation.

Thanks to its carefully chosen orbit, Venus Express is strategically positioned to investigate this process; the spacecraft travels in a highly elliptical path sweeping over the poles of the planet.


“At Venus, the solar wind strikes the upper atmosphere and carries off particles into space. Planetary scientists think that the planet has lost part of its water in this way over the four and a half thousand million years since the planet’s birth.”

Water is a key molecule on Earth because it makes life possible. With Earth and Venus approximately the same size, and having formed at the same time, astronomers believe that both planets likely began with similar amounts of the precious liquid. Today, however, the proportions on each planet are extremely different. Earth’s atmosphere and oceans contain 100 000 times the total amount of water on Venus. In spite of the low concentration of water on Venus Delva and colleagues found that some 2x1024 hydrogen nuclei, a constituent atom of the water molecule, were being lost every second from Venus's day-side.

more:

http://www.esa.int/esaCP/SEM8MYSTGOF_index_0.html

[Lasher]

1. Four and a half thousand million years.

Isn't that pretty much like 4.5 billion?

[RC]

2. Yeah, I think it's roughly comparable.

Give or take a few days.

[Pab Sungenis]

3. British standard.

In the US "Billion" = 1,000 Million. In Britain, "Billion" = 1 Million Million.

[Lasher]

5. So a billion in the UK is a trillion in the US.

But then again, a UK trillion is a US quintillion.

Hard tuh figger dem fellers frum across thuh pond.

[GreenPartyVoter]

6. A billion isn't a million million here in the USA? Dang, I had it wrong all these years! LOL

[izquierdista]

4. I believe she is standing on it

[scubadude]

7. Their system and ours is the same in this case.

Four and a half thousand millions is 4.5 billion. This happens to be roughly the age of the planets in our solar system.

Planets will all lose their atmosphere unless they have enough mass to retain it. The earth is just large enough too but Mars is too small. Mars has lost almost all of it's atmosphere.

I'm missing something here surely?

Scuba

[n2doc]

8. But the point of the article is about magnetic fields

Earth has one. Venus doesn't. So Venus gets struck directly by the solar wind, blowing off water, while earth is protected to a much greater degree.

[scubadude]

9. I was reading way to fast and missed the magnetic field part, but...

I'm still missing something.

The side of Venus that faces the sun has an average temperature above 900 degrees, way to high for water to exist in it's liquid state. Maybe the pressure is high enough on Venus to retain it's water even at that high temperature? High enough to melt lead, right?

O.k. so stripped of it's magnetic field there would be nothing to prevent the sun from scouring away it's atmosphere, with lighter water molecules being stripped off first? Wait, Venus has an atmosphere much denser than earths...

I guess they have a point of sorts. I believe the hydrogen they are finding is being stripped from something other than water.

Right? Maybe they are wondering too.

Perhaps it is just me who is particularly dense tonight! LOL Sorry for so many questions, my poor dad when I was a kid!

Scuba

[n2doc]

10. It is fairly complicated

Yes, Venus would still be really hot even with water. But if it were like the Earth that water would have mostly remained in the atmosphere. Venus is really hydrogen depleted compared to earth. Even though it is thought the two started off with similar compositions, and are roughly the same size.

People also talk about Venus having a lot of "sulfuric acid" in its atmosphere. I don't know if that is another potential source of H.

There are also theories that state that Venus has no/ or very odd/ plate tectonics. And that this is because there is no water to "lubricate" the process. With no recycling of rock all the CO2 has gone into the atmosphere, making for a very strong greenhouse effect.