Mars

[Professur]

Just something bugging me. Mars has volcanos, so, tetonically, it should have similar geological properties to Earth. So ...... where are the continental plates?

 

[chcr]

Just something bugging me. Mars has volcanos, so, tetonically, it should have similar geological properties to Earth. So ...... where are the continental plates?

Had volcanos, was tectonic. On a geologically dead world like Mars, I would expect it to be hard to pick out the plates without deep-sounding radar and the like. The reason they're so (relatively) easy to pick out on Earth is that they're still moving. I would expect them to be there, but you don't really know until you see them. We only have good data on one planet so far.

 

[Professur]

Mars volcanoes not dead, just resting
By Lucy Sherriff

Reports of Mars' geological death might have been greatly exaggerated, according to researchers working on the European Space Agency's Mars Express mission.

Images from the orbiter reveal volcanic cones at the planet's north pole that are unmarked by craters, suggesting that they erupted relatively recently, the BBC reports.

The amount of cratering on a planetary surface is a widely accepted method of estimating that surface's age, and assumes a steady rate of impacts on planets, over the last four billion years or so.

Dr. Gerhard Neukum from the Free University in Berlin, and the principal investigator for the High Resolution Stereo Camera (HRSC) on Mars Express, told delegates at a meeting of planetary scientists in Cambridge:

"Mars is a planet that was very recently active - maybe one, or two, or three million years ago."

He said that the cones give him the impression that Mars could still be geologically active, even today. Volcanic activity on Mars is thought to have reached a maximum around 1.5bn years ago.

He acknowledged that it was possible that if the cones were ancient features, any cratering could have been eroded by the Martian winds. But he said the region - which features somewhere between 50 and 100 volcanoes - showed no other wind-related features. He also noted that some traces of the craters should remain, and that he could see none.

Dr. Neukum also proposes that volcanic activity and glacial activity on the planet are linked, but other scientists think the inclination of the planet's orbit around the sun has a bigger influence on the movement of water. ®

Source


I beg your pardon?


But, more importantly, earth's plates are visible even without detecting movement. Drain the water out of the oceans and a blind man could see it with a stick. The mountain ranges, and mid-oceanic rifts are kinda hard to miss. But Mars seems to have had one super-continent, and one super-ocean. And that's it. Why so different?

It's speculated that earth's moon was formed when a mars sized planetoid colided with earth, shedding the greater part of both their crusts into space to form the moon, (which has very little iron) and dumping most of it's iron core into ours. It makes me wonder it perhaps that is still having some effects on us. That would explain why our core spins faster than the rest of the planet, without which we'd have no Van Allen belts. It could also still be off-center some, which would stir the molten iron outer core and the molten rock mantle. With the density difference, it wouldn't slow appreciably for eons. Similarly, neutron companion stars have been speculated to orbit with the perimeter of red giant stars without any greater resistance than in vacumn.

If that's the case, then life-bearing (in our terms) planets could very well be one time, blind chance happenings.

 

[MrBishop]

Seems like you just answered your own question, Prof. Maybe Mars needed that kind of impact or a fast-spinning core to cause plate tectonics. No cracked surface into seperate planes=no plates to move.

 

[chcr]

Or perhaps the evidence is there but after millions of years of relatively unimpeded meteor strikes and dust storms they simply can't be seen from space anymore. Why so different? Why should you expect it to be similar? As I say, we have good data (not complete, mind you) on one planet. Drawing conclusions about what other planets should be like is premature at best, IMO. It will be the way it is. Determining why it's that way will require researchers on the spot and decades if not centuries of study. I still expect them to find evidence that the similarities outweigh the differences, but again, there is no scientific basis for that conclusion and it may certainly be 180 degrees from reality.

 

[Professur]

Seems like you just answered your own question, Prof. Maybe Mars needed that kind of impact or a fast-spinning core to cause plate tectonics. No cracked surface into seperate planes=no plates to move.

I know I give one speculation, dreamed up out of my own warped cranium. But I find it unusual that I've not heard anything similar from the science community. I've not heard one discussion concerning the lack of plate tetonics on Mars, and I've been a planetary science buff for near 30 years.

 

[Dave]

If that's the case, then life-bearing (in our terms) planets could very well be one time, blind chance happenings.

one time, very unlikely. rare possibly. if even a small percentage of visible stars have planets circling them, that would equate to an awful lot of planets out there. odds are good that something similar has happened elsewhere as far as collisions and plate tectonics go.

 

[Professur]

one time, very unlikely. rare possibly. if even a small percentage of visible stars have planets circling them, that would equate to an awful lot of planets out there. odds are good that something similar has happened elsewhere as far as collisions and plate tectonics go.

But if the odds of all the circumstances that we thought were necessary to life occuring again were one in 100 billion, they just went up by a factor of, what, another 100 billion?

 

[JJR512]

Maybe I'm missing something. It seems like you're saying that, because a planet does not have moving plates, the chance of life occurring on it becomes nonexistant or much, much smaller. Does a planet need to have moving plates to have life? How can we be sure one way or the other?

 

[MrBishop]

I know I give one speculation, dreamed up out of my own warped cranium. But I find it unusual that I've not heard anything similar from the science community. I've not heard one discussion concerning the lack of plate tetonics on Mars, and I've been a planetary science buff for near 30 years.

http://www.sciencenews.org/pages/sn_arc99/5_1_99/bob2.htm
http://science.nasa.gov/newhome/headlines/ast29apr99_1.htm
http://www.platetectonics.com/article.asp?a=12&c=13
http://www.stanford.edu/dept/news/pr/93/931206Arc3014.html
http://www.lukew.com/marsgeo/tectonic3.html
http://pubs.usgs.gov/publications/text/unanswered.html
http://www.ocean.washington.edu/people/grads/mpruis/research/mars95.html

Maybe you've been looking the wrong way or it just wasn't popular enough to print.

Gotta Love Google

 

[MrBishop]

Does a planet need to have moving plates to have life? How can we be sure one way or the other?

We can't be sure.

Not sure about the link between plate tectonics and life myself. Vulcanism and outgassing helps though. Since Volcanos are linked to plate tectonics, that might be what Prof's getting to.

Prof?

 

[Gonz]

Maybe I'm missing something. It seems like you're saying that, because a planet does not have moving plates, the chance of life occurring on it becomes nonexistant or much, much smaller. Does a planet need to have moving plates to have life? How can we be sure one way or the other?

Using our only source (Earth) as a basis, the answer would have to be yes.

 

[JJR512]

Using our only source (Earth) as a basis, the answer would have to be yes.

Yeah, but that's part of my point...With only one model, it's hard to say what the other possibilities are. I mean, you know that theory or maxim or whatever it is, I forget who said it, but it's something like, no matter what we try to imagine, what's really out there is probably far, far stranger.

 

[chcr]

Not only is the universe stranger than we imagine, it is stranger than we can imagine.

--Sir Arthur Eddington
--English astronomer (1882 - 1944)

 

[Dave]

But if the odds of all the circumstances that we thought were necessary to life occuring again were one in 100 billion, they just went up by a factor of, what, another 100 billion?

not if you are postulating that a planetary collision and plate tectonics are requirements for life to evolve. if those are the two main criteria, the odds would go down with the higher number of potential candidates.