Weird Oblong Crater Deepens Mars Mystery

[n2doc]

By Lisa Grossman August 27, 2010 | 1:53 pm | Categories: Space


This amoeba-shaped depression on Mars, called Orcus Patera, has had planetary scientists scratching their heads for decades. Despite these sharp new images from the European Space Agency’s Mars Express spacecraft, the crater’s origin is a complete mystery.

Orcus Patera, discovered in 1965 by the Mariner 4 spacecraft, is located near Mars’ equator, between the volcanoes Elysium Mons and Olympus Mons. At 236 miles long, it would stretch from New York to Boston on Earth. Its rim rises over a mile above the surrounding plains, and its floor lies 1,300 to 1,900 feet below its surroundings.

But in spite of lying between two volcanoes and its designation as a patera — the name for deep, complex or irregularly shaped volcanic craters — scientists aren’t at all sure that Orcus Patera has a volcanic origin story. It could be a large impact crater that was originally round but later deformed by compressional forces. Or it could have formed after the erosion of aligned impact craters. The most likely explanation is that it was made in an oblique impact, when a small body struck the surface at a very shallow angle, like a rock skipping on a pond.

The new images show that the crater’s rim is criss-crossed by rift-valley-like structures called graben, which are evidence for active tectonic forces in the area. Smaller graben are also visible inside the depression itself, suggesting that several tectonic events have stretched the ground. The depression also shows “wrinkle edges,” which indicate that the ground has been compressed as well as stretched. The dark shapes near the center of the depression were probably formed when dark material dug up by small impacts in the depression was blown around by the wind.



Read More http://www.wired.com/wiredscience/2010/08/oblong-martian-crater/

[Richard D]

1. Obviously . . . .

. . . a giant footprint.

[ChairmanAgnostic]

3. Nope, the remnants of a laser blast.

the walls eventually eroded and caved in.

[DJ13]

2. A giant cosmic dog?

[KansDem]

4. Could the moon have been struck by a meteor coming at it from an angle?

Looks like a meteor struck it and ricocheted.

But then, I'm not a cosmologist...:shrug:

[Esra Star]

7. I agree.................nt

[damntexdem]

5. Giant Sasquach footprint.

Why can't the astronomers figure that out?

;-)

[rocktivity]

6. I thought the slab was on Jupiter.

:shrug:
rocktivity

[Fumesucker]

8. Here are pictures of a pair of impact craters on the Argentine Pampas..

Note the similarity in shape to the Mars crater.





http://www.thelivingmoon.com/43ancients/02files/Earth_Images_07.html

And then there is this oblique impact crater on Venus.



The crater Schiller on the Moon.

[krispos42]

9. The gravesite of Mars' potential 3rd moon, perhaps? n/t

[GreenPartyVoter]

10. Amoeba? I'm seeing something more Paramecium-shaped, I think.

[Orrex]

11. I've never heard anything cilia than that.

[GreenPartyVoter]

13. LOL

[dimbear]

12. OK, think I get the name now.

Patera is Latin for a sacrificial plate. In the actual real world, Orcus is an old god of the underworld similar to Hades, or Neptune, but some witty citizen noticed the similarity between the crater and what you would get if you smacked Mars at high speed with a killer whale of sufficient size, i.e., an orca.

[chillspike]

14. Glacier?? (nt)