Mars reliefs

[ballaratdragons (Ken)]

Originally Posted by erick

But the parachute has to be enormous - Mars Atmosphere is on average less than 1% of Earth's!

But it won't fit down the hole

[bojan]

More on holes on Mars here:
http://www.universetoday.com/2007/08...es/#more-11696
It seems they are actually very deep pits.... but the bottom is still not visible..

[ispom]

do you remember ?

a deep hole was found on Mars

http://www.space.com/scienceastronomy/070605_mars_hole.html

now there is a new view of the Dark Pit on Arsia Mons !

http://www.2-0.scienceticker.info/wp-content/uploads/2007/08/mars-hirise-loch.jpghttp://hirise.lpl.arizona.edu/PSP_004847_1745

From the shadow of the rim cast onto the wall of the pit we can calculate that the pit is at least 78 meters deep,
presumably an “einsturzkrater”
(can’t translate, sorry) perhaps: a crater originated by collapsing of the surface

and now:
more entrances to caves along the slope of a Martian volcano discovered,
now we know 7 such holes

http://www.jpl.nasa.gov/news/news.cfm?release=2007-106

[Ric]

Fantastic stuff Ispom, I cant help but wonder what's down there. I reckon 78 metres is enough to protect a lot of things from the harsh surface.

Cheers

[glenc (Glen)]

APOD today has the same image.
http://antwrp.gsfc.nasa.gov/apod/
Explanation: In a close-up from the HiRISE instrument onboard the Mars Reconnaissance Orbiter, this mysterious dark pit, about 150 meters across, lies on the north slope of ancient martian volcano Arsia Mons. Lacking raised rims and other impact crater characteristics, this pit and others like it were originally identified in visible light and infrared images from the Mars Odyssey and Mars Global Surveyor spacecraft. While the visible light images showed only darkness within, infrared thermal signatures indicated that the openings penetrated deep under the martian surface and perhaps were skylights to underground caverns. In this later image, the pit wall is partially illuminated by sunlight and seen to be nearly vertical, though the bottom, at least 78 meters below, is still not visible. The dark martian pits are thought to be related to collapse pits in the lava flow, similar to Hawaiian volcano pit craters.

[Dujon]

How intriguing. Thanks for all the various links provided.

Looking at the image referenced by Glen (and others) I can't visualise a geometry which would allow for the object to be a shaft. The lighting - to my mind at least - seems to signify a hole through a significant amount of rock (or whatever) into a void.

Most of the seven images are close to circular. Why? Perhaps these are collapsed domes or, maybe, even caused by a meteorite punching through the skin of the volcano. In the latter case I would think that the depth of the 'hole' would have to be significant otherwise the pressure wave produced by its final impact would surely have caused some ejecta to be visible. A small impacting body which, on contact (after piercing the upper skin) caused the weakened area to collapse also seems unlikely as I would again suspect that some ejecta would be clearly visible.

The image of 'Jeanne' or 'F' in the montage of the seven sisters does appear to have some outflow, though whether that is ejecta or lava flow I have no idea.

Definitely intriguing.


*edit*

Sorry, Ispom, I forgot to include that I too have the problem of "up" and "down" when it comes to some images. At times it's hard to convince the mind that it's giving me wrong information.