NASA photographs mysterious circle on Mars

[UM-Bot]

The space agency has released a new image of a peculiar circle on Mars - but what exactly is it ?

http://www.unexplained-mysteries.com/news/306225/nasa-photographs-mysterious-circle-on-mars

[keithisco]

I think they have answered their own question - it looks like an impact crater that has been infilled.

[Troublehalf]

Could it be an impact crater that had areas of the polar landscape 'melted' or heated from the impact, that then eventually 'scabbed' over when the temperature cooled? Either way, if it's not been seen before and it's a new thing, it doesn't really matter if it's a simple explanation or not.

[MJNYC]

I was hoping for more....

[bison]

The entire area has a similar pebbly texture. The size of the 'pebbles' in and around the circular feature seem somewhat larger. It appears possible that a cratered terrain interacted with the geological mechanism that produced the pebbly surface, to produce this effect. Perhaps the steepness of the circular walls was involved, and/or some chemical change in the soil caused by the impact of the supposed cratering event.

[Dakotabre]

Anyone else notice the lines on Mars in the photo on the cnet page?...The Long Straight Ones. Kind of like the Nazca Lines? Wonder if they would match up to any?

[bison]

Now that you mention it, I do see the dark straight lines. They are more obvious in the version of the image in the cnet article. It covers a wider area. The most prominent of these lines crosses the large circular feature, without apparent interruption or change. Since these lines are oriented in various directions, it seems unlikely that they are due to a scanning artifact in the image.

[paperdyer]

Could the lines just be from where all the shots are put together to form the pic?  Except for the dark shadowy one of course.

[bison]

All the lines are dark, to some degree. This is simply more obvious in the one crossing the circular feature. Hard to see why the joins between images should be dark at the edges. I looked into the issue of dark, linear surface features on Mars, but all that was turned up was informations on the Martian 'canals' and how their existence was long ago disproven.  

[pallidin]

That is one very old impact crater, it seems.

[pallidin]

11 hours ago, Dakotabre said:

Anyone else notice the lines on Mars in the photo on the cnet page?...The Long Straight Ones. Kind of like the Nazca Lines? Wonder if they would match up to any?
 

Nah, those are lines formed many years ago by Martian motorcycles.

In all seriousness, though, it would be curious to investigate that site, and those lines, presuming it's not an imaging artifact.

[bison]

HiRISE is essentially a close-up, detail-oriented imager. The round feature should be somewhere between 150 meters and 750 meters in diameter. No indications were found that the full image, which is 1200 to 1600 meters across, was a panorama made up of separate images.

[ChrLzs]

The darkish lines are simply tracks from the frequent 'dust devils' that blow across the surface.  This area is obviously fairly flat and thus the winds tend to blow straight across it (these tracks are often curved) and because of that the d-ds go in pretty straight lines, thereabouts...

As for the crater, not really my area... but here's a cropped, higher res version of that image, with a slight contrast enhancement: