Earth like process on Mars.

[chew_on_this]

Another interesting article etc, etc.<br /><br />http://g.msn.com/0US!s9.31612_317621/92.c587/2??cm=Discovery.comnews

 

[bobvanx]

The location of the high intensity striping looks like another clue to how Mars is different, as well. Do you recall the core/mantle heat flow experiments conducted, I think, on the shuttle? They showed that there are many ways for the internal heat of a planet to organize layers, and one of these skips over the Earth's pattern of core/mantle/surface and the associated convective flow patterns. The layer structure that reminded me of Mars, for some reason, had the core coupled directly to the surface along one hemisphere. The heat flow became very smooth across that section. And the entire system cooled down much more rapidly than a multi-layer structure. At the time, I thought, "Well! That would explain why the northern plains are so flat, because they didn't develop a mantle/crust!"

 

[jatslo]

<font color="yellow">core/mantle heat flow experiments conducted, I think, on the shuttle</font><br /><br />This is experiment is relatuve to something that I am working on, so if you find a link, that would be great.

 

[chew_on_this]

Geology is not my forte'. I understand the process of convection, but not the initiation of it. What started the flow of the crust as it does on earth and why did mars not follow suit? Size could be a big factor I would imagine, rapid heat loss, atmosphere, etc, etc. Far flung but maybe mars is in a flip flopping stage of it's magnetic field, much like earth, and/or the process stalled and that's what we are seeing. Isn't speculation fun!

 

[earthseed]

I could not find the article referenced in the first post, but I assume it is similar to New Mars Map: Similarities to Earth Revealed from space.com.<br /><br />It is believed that Earth's moon was formed by a collision with a large body. One theory claims that this process removed most of the Earth's crust, and deposited it on the moon. This thinner crust is what makes plate tectonics possible. The constant recycling of the crust by plate tectonics is critical for supporting life over the long term. A key prediction of this theory is that our neighboring planets will have thicker crusts, and thus no plate tectonics as on Earth. Do these findings falsify that prediction?<br /><br />Subduction is the process by which one plate passes underneath another, and gets re-cycled into the interior. This is critical to how plate tectionics works on Earth, and is much more difficult when plates are thicker. Evidence for subduction on Mars was not mentioned.<br /><br />Convection in the core of a planet is not affected by the thickness of the crust. It is driven by heat released by radioactive decay of elements in the planet's interior. Both Venus and Mars have long canyons, probably formed by plates splitting apart. But one consequence of subduction is long volcanic mountain chains. These are not found on Venus and Mars. The short chain of Tharsis volcanoes is caused either by a moving hotspot, or a plate sliding over a stationary hotspot. It is hard to imagine a plate sliding very far without it subducting somewhere on the other end.<br /><br />I find the information provided is not conclusive in settling this question. It is all consistent with plates jostling on the surface, but not subducting.

 

[chew_on_this]

<font color="yellow"> I understand the process of <font color="red">convection</font> but not the initiation of it.</font><br /><br />Oops, meant subduction here.

 

[earthseed]

The simple answer is heat from radioactive decay is added to the system. This heat flows toward the surface, providing energy for convection. A more complex answer is found here:<blockquote><em>Heat within the Earth comes from two main sources: radioactive decay and residual heat. Radioactive decay, a spontaneous process that is the basis of "isotopic clocks" used to date rocks, involves the loss of particles from the nucleus of an isotope (the parent) to form an isotope of a new element (the daughter). The radioactive decay of naturally occurring chemical elements -- most notably uranium, thorium, and potassium -- releases energy in the form of heat, which slowly migrates toward the Earth's surface. Residual heat is gravitational energy left over from the formation of the Earth -- 4.6 billion years ago -- by the "falling together" and compression of cosmic debris. How and why the escape of interior heat becomes concentrated in certain regions to form convection cells remains a mystery.</em></blockquote>So we know heat is moving, but not why it forms a convection pattern. But convection may not be that important.<blockquote><em>Most scientists now favor the notion that forces associated with subduction are more important than seafloor spreading. Professor Seiya Uyeda (Tokai University, Japan), a world-renowned expert in plate tectonics, concluded in his keynote address at a major scientific conference on subduction processes in June 1994 that "subduction . . . plays a more fundamental role than seafloor spreading in shaping the earth's surface features" and "running the plate tectonic machinery." The gravity-controlled sinking of a cold, denser oceanic slab into the subduction zone (called "slab pull") -- dragging the rest of the plate along with it -- is now considered to be the driving force of plate tectonics.</em></blockquote><br />If slab pull is required for plate motion, how can there be a

 

[chew_on_this]

I recall an article on Venus that its' crust undergoes a massive resurfacing every 1/2 million years(?) or so. This must be the release of heat/pressure buildup and the crust is then sucked under in one fell swoop to cool the core down until the next buildup and resurfacing. Not sure about Mars, I'd say it's dead or nearly so.

 

[earthseed]

I think that may be more like every half billion years. There is every reason to believe that Venus has much the same internal energy as the Earth. It lacks a magnetic field, and the recycling of material due to subduction, but the original heat and radioactive decay of elements is probably similar. The lack of energy release by Earth-like plate tectonics may explain such extreme release events.<br /><br />Mars is much smaller, and has lost most of its internal energy.