Orcus Patera on Mars.

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Below copied EarthlingX post from the ESA MArs Express thread in M & L.

http://www.esa.int : Mars’s mysterious elongated crater

27 August 2010


Orcus Patera on Mars

Orcus Patera is an enigmatic elliptical depression near Mars’s equator, in the eastern hemisphere of the planet. Located between the volcanoes of Elysium Mons and Olympus Mons, its formation remains a mystery.

Often overlooked, this well-defined depression extends approximately 380 km by 140 km in a NNE–SSW direction. It has a rim that rises up to 1800 m above the surrounding plains, while the floor of the depression lies 400–600 m below the surroundings.

Above courtesy of EarthlingX

I thought this was worthy of it's own thread on here.

Thanks EarthlingX,

Very, very interesting. An elongated crater that to me looks lava filled, perhaps a glancing impact, which filled with lava???.

I'll submit a request to the MRO HiRISE team to get a really hires view of the interior, to see the density of smaller impact craters & / or erosional evidence to help ascertain it's age.

Similar curious elongated craters of similar ilk to Orcus Patera have also been found on Mercury & the Moon.

220 Km by 120 KM Sveinsdottir Crater on Mercury.


179 KM by 71 KM Schiller Crater on the Moon.


380 KM by 140 KM Orcus Patera on Mars.


Below also a copy of post from EarthlingX.

Thanks EarthlingX,

Very, very interesting. An elongated crater that to me looks lava filled, perhaps a glancing impact, which filled with lava???.

It could be lava filled, but could also be filled with water sediments or wind. My first impression was a glancing multi-body impact (3-4). It looks rather young, but obviously older than those crossing 'graben' or fissures, or perhaps interior got filled later ?

There is a similar elongated crater on the left top rim, but much smaller.

I'll submit a request to the MRO HiRISE team to get a really hires view of the interior, to see the density of smaller impact craters & / or erosional evidence to help ascertain it's age.

Very nice I was checking available images of the area, but none of those i found covers the whole feature, or at least not as detailed as we got spoiled by the HiRISE

There are at least two images, but they are covering the rim and not the interior, and only half of the whole thing.

Andrew Brown & EarthlingX.

 

[SteveCNC]

you know I thought glancing at first but the more I look at it the more I think it was probably a large object that broke up coming in and spread out in a line before impact . It is a very interesting object though , someday people might dig around on it and see what it was .

 

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Thanks Steve,

Could well be. the pieces impacting very close together with the depressions filling in simultaneously. Very plausible indeed. Perhaps MARSIS or SHARAD Radars may help with that.

Orcus Patera runs North - South, ESA rotated it 90 degrees.

Hi EarthlingX.

Yes there is not much from HiRISE concerning Orcus Patera.

I did find after some searching a sample from the interior floor, so my request may be a moot point, maybe not. Further observations with HiRISE would not hurt though.

MRO HiRISE close up of fracture on floor of Orcus Patera.

To me this looks like an old feature. The floor is very dusty & has a large number of small craters.

Some crops I did below, each section is only approx 150 metres across.


Small crater with dunes on the floor of Orcus Patera. It is about 200 metres wide.


A couple of small craters on the north wall of Orcus Patera.


I will be back later with some more.

Andrew Brown.

 

[EarthlingX]

Here are Orcus Patera images i found on HiRise :


Fracture in Orcus Patera (ESP_017191_1935)


Wall of Orcus Patera (ESP_016624_1925)


Central Hills within Orcus Patera (ESP_012879_1960)


Northern Rim of Orcus Patera (PSP_006471_1975)

This is an example of a crater chain :

Pit Crater Chain Cutting Lava Flow in Southwest Alba Patera (PSP_003660_2155)

Nice work with those crops Andrew, but you spoiled us already :mrgreen:

There's a lot of very eroded craters in the interior, some of them have almost disappeared.

 

[3488]

Thanks EarthlingX. A few views, looks like a very old feature checking out your other links.

An area approx 1 KM wide on the floor of Orcus Patera within the hills, small hills & tiny craters.


A few more crops from me.


Hills within Orcus Patera, with dust slides.


Andrew Brown.

 

[silylene]

.....An elongated crater that to me looks lava filled, perhaps a glancing impact,......
Similar curious elongated craters of similar ilk to Orcus Patera have also been found on Mercury & the Moon.
......

And a similar string of multiple craters has been found on Earth, on the pampas of Argentina. The meteor broke up in the atmosphere and hit at a very acute angle with multiple strikes. There was a very nice article about this in Science about 10 years ago, I recall, and a couple of artciles in S&T too (originally the meteoric origin was controversial). Wiki article here: http://en.wikipedia.org/wiki/Rio_Cuarto_craters

More pictures of this fascinating crater field here: http://www.unb.ca/passc/ImpactDatabase/images/rio-cuarto.htm

There were ten depressions, four of them of substantial size. One crater, named the "Drop", was about 200 meters wide and 600 meters long. Two more large craters, the "Eastern Twin" and "Western Twin", both about 700 meters wide and 3.5 kilometers long, were located 5 kilometers to the northeast. Another major crater, the "Northern Basin", about half as big as one of the Twins, was sited 11 kilometers further to the northeast. The long axes of the craters all pointed to the northeast........Samples of materials obtained from the depressions indicated the presence of shocked materials, as well as pebbles that were clearly of meteoritic origin.....Models of the Río Cuarto event suggest that the object struck at an angle of no more than 15 degrees from the horizontal, with the impact itself having 10 times more explosive energy than the Barringer Crater event and 30 times more than the Tunguska event[citation needed]. Although the age of the craters has not yet been determined precisely, it is believed they are about 10,000 years old, placing them at the start of the Holocene.