Round Thing Near South Pole Options

[antoniseb]

Here is an image which I think is from Mars Odyssey, but I'm not certain. It is from one of the orbiters. Thanks to a friend in another forum for pointing it out.

It shows a dark, very close to circular, ring near the extremities of the polar cap.

http://www.msss.com/moc_gallery/e13_e18/me...14/E1401276.jpg
http://www.msss.com/moc_gallery/e13_e18/im...4/E1401276.html

It may be that this feature has already been discussed here, if so can someone please point me to the discussion. Otherwise, I am curious to know what you think may have caused this.

[Decepticon]

Wow!

I would love to land a rover here.

[antoniseb]

I would love to land a rover here.

The circle is about 4 kilometers in diameter, so that would be just about right for one of the rovers.

[Guest_Myran_*]

Interesting, I took the opportunity to lighten that dark part and found concentric lines running around the rim.
Yes inspired by the great work of others here Myran have done the first ever image enhancement, nothing added but not entirely true to he original either.

In lack of a better explanation I would guess its a crater, if its impact or a volcanic caldera im unable to judge, but the enhanced image makes me go for a wild guess at caldera.

[Jeff7]

Perhaps it's from an impact when the ice cap was melted slightly - maybe slushy, and then it refroze?

[RNeuhaus]

I don't think it is a volcanic crater. It might be of an 90 degree vertical impact of a perfect sphereal meteor when the land was somewhat mud, a mix of sand and water. The meteore impact might have happened when the land was covered by ice or snow.

Rodolfo

[Bob Shaw]

Here is an image which I think is from Mars Odyssey, but I'm not certain. It is from one of the orbiters. Thanks to a friend in another forum for pointing it out.

It shows a dark, very close to circular, ring near the extremities of the polar cap.

http://www.msss.com/moc_gallery/e13_e18/me...14/E1401276.jpg
http://www.msss.com/moc_gallery/e13_e18/im...4/E1401276.html

It may be that this feature has already been discussed here, if so can someone please point me to the discussion. Otherwise, I am curious to know what you think may have caused this.

Is there a 2Km high MER nearby, and is this a RAT hole?

[David]

Ask Paxdan; he's been known to create features similar to this one.

[Guest_Myran_*]

Oh yes, I side with you Jeff7, and I said I was very uncertain. One impact that melted the ice to some degree and the energy for one impact does not have to be from a perfectly round object - it could have been quite smaller but the energy from the impact spread in one even way. But the darm rim are unusual and could be material from underneath, any chanse of retargeting Phoenix? (Just kiddin) But it would be one good idea to check this feature out some time in the future.

[Guest_Richard Trigaux_*]

I think you should not be excited you all: patterns of parallel straight lines are common in Martian ice caps. The more common explanation is that these ice caps are formed of layers of water ice, dust, carbon dioxid ice... When an ice cap evaporates (and not melt, it is impossible in today Mars conditions) evaporating starts from the border of the ice cap, while lefting the top untouched (because the redish soil around is hotter than the white ice). So the ice cap erodes in a way to cut through all its layers (like in Colorado Canyon) showing, from above, sets of numerous parallel lines. It is most probably what hapened here. Why is it circular? probably because it started from a spot, a meteorite impact, or an underlying crater.

By the way if an impact makes ice melt, the resulting water will stlle in hollow in a matter of some minutes and freeze in some hours, far after any wave is dissipated: it is impossible to freeze a wave.

[ljk4-1]

Is there a 2Km high MER nearby, and is this a RAT hole?

Martian NASCAR track?

[Guest_Myran_*]

Richard Trigaux said: it is impossible to freeze a wave.

I never suggested anything such either.
When water freeze its expands somewhat. On larger areas of water this creates ice ridges since the small expansion are multiplied many times over and you get a stress so large that sheats of ice piles up in long lines.
As a child I often crawled into the triagular cages that they have within, a magical kingdom with a very special light perfect for my childhood fantasies.
But back to the question at hand here, if we start with one perfectly round lake
caused by one meteor impact or volcanic heat doesnt actually matter, the pushing action of the freezing water would push against the hard shore of frozen ice that surrounds it on all sides.
Since it started out with a round shape from the very start it would tend to freeze towards the center with circles within circles.
A more important question is why it have a dark edge, im unable to answer that.

[RNeuhaus]

A more important question is why it have a dark edge, im unable to answer that.

The dark land is due to ,maybe, the fact that the land is wet so it appear to be darker than a dry land.

Rodolfo

P.D.The only thing that can make a perfect circle is the water waves after an impact.

[Guest_Richard Trigaux_*]

About freezing waer waves:

I never suggested anything such either.

This is a common suggestion, which was often proposed, so I tried to dismiss it. But your own explanation about freezing lakes making geometrical paterns is interesting, and we could expect to find such things on Mars if there are somewhere frozen lakes. I think that large floods of water flowed on Mars, from volcanic origin or breaking up water tables. This water necessarily ended somewhere, where we may find such effects you describe.



About freezing waer waves:

caused by one meteor impact or volcanic heat doesnt actually matter,

Yes it matters. Meteorite impacts are common and not very interesting, while a recent volcanic activity would be. Now we think that volcanic activities on Mars started at least 2 billions years ago, eventually had a maximum, but dit not really ended today. Only eruptions are one over 10-40 million years.

[RNeuhaus]

About freezing waer waves:
Yes it matters. Meteorite impacts are common and not very interesting, while a recent volcanic activity would be. Now we think that volcanic activities on Mars started at least 2 billions years ago, eventually had a maximum, but dit not really ended today. Only eruptions are one over 10-40 million years.

Mmm...the recent news says that the most recent Mar's volcanic activities was around 1-10 millions years ago...Indeed very recent.

Rodolfo