On Feb 1, 8:51 am, Mega <masterstorm...@gmail.com> wrote:
> Venus probably once had liquid oceans for some (or maybe more) million
> years.
>
> But all the water was split into hydrogen and oxygen. Hydrogen
> escaped into space - Venus is dead... Even if you could cool Venus
> down 450°C (to make temperatures +25°C), there was no water at all, so
> you could build permanent bases up there, but it won't ever be like
> Earth with rivers and seas again.
>
Venus is dead with an abundance of energy to revive it. Not all the
water has been split and not all the hydrogen is gone. There is more
total water vapor in the Venusian atmosphere than the Martian one and
it's at a higher absolute concentration (and there's plenty of energy
to collect it), similarly, there's plenty of hydrogen, oxygen, and
carbon to be had. True, we won't coat 70% of Venus' surface with water
without finding a celestial source of it, but the same is true for
Mars. Further, even if we put the water on Mars, we then have to thaw
it and keep it on the planet. If Venus is dead, Mars is dead and the
body is cold.
>
> As Cathal said, you need a gradient. Maybe the solid surface is a bit
> cooler than the air?
>
There's a great gradient running upwards from the surface of the
planet. It's kinda funny that this is seriously a question. The
atmospheric surface is 250K. Not surprisingly, this region contains
the most water vapor and what is considered 'breathable air' (20%
Oxygen, 70% Nitrogen). 50km below this level you have the surface of
the planet at 700K. Even ignoring massive thermal gradients, chemical
fixation, and atmospheric mixing as energy sources and looking
strictly at solar. Mars is still just as dead as Venus and gets a
fraction of the solar radiance.
> Recently a new geological model for Venus was developed:
> Voltailes as water (just a few 0.01 weight percent) make rocks melt at
> lower temperatures. So tectonics developed at the Earth.
> Venus had left nearly all its water. So the crust was thicker and no
> heat could escape. Then after some time, a global eruption set free
> large amounts of heat and gases.
> Such eruptions occur every (I think to remember) 100 Millions of
> years.
> Yet this form of heat transport makes Venus lose much more of it's
> core heat a study has shown. So Venus' core is likely to cold to
> produce a magnetic field.
You're misinterpreting the theory. The problem isn't that Venus' core
is too cold, it's that it's too hot and too homogeneous. Venus'
interior is so hot that it periodically melts its crust (but it's
somehow colder or cooling faster???); this convection, combined with
slower rotation, causes Venus to have a poor magnetic field. If you
took Earth's iron core and mixed it with the mantle and crust, and
slowed the rotation, you end up with a much poorer magnetic field.
And, once again, there is a weak magnetic field around Venus whose
sources are hypothesized, one thing is clear though, Mars' core used
to be hot and magnetic and now it is neither.
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