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loglo
2007-Aug-25, 05:37 AM
Hi all,
I seem to recall someone posting an article here on finding northern analogues of the "black smokers" found near the south pole of Mars. The search function has not turned anything up, does anyone have any info on that find?

I though I had found some myself but they turned out to be rock ledges when I found the source and turned it upside down! Interpreting the images is a little more difficult than I had imagined. :) (see below)

thothicabob
2007-Aug-30, 04:59 AM
I recall an article on possible voids being discovered (extrapolated by apparently very 'deep' holes on the surface being noted which appear to be deeper than can be determined from the imaging and comparing shadows/time of day to find bottoms, leading to the assumption that these are openings to larger subsurface voids, or caverns).

These could also possibly harbor environments more conducive to life than conditions on the surface (possibly warmer (liquid water?), less damaging radiation, etc.). I've been looking for some follow-up information on the subject, but so far haven't heard much since the subject was raised a bit earlier in the year.

Could this be what you're referring to?

Here's a link to a paper on the subject: http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1371.pdf

01101001
2007-Aug-30, 05:47 AM
Here's a link to a paper on the subject: http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1371.pdf

Today's news is that one, maybe all, are vertical pits, not caves. See article in topic Caves spotted on Mars (http://www.bautforum.com/1060805-post52.html). They are deep-ish, 80 meters maybe in the one imaged, but not as deep as a cave might have been.

Earth's Cave of Swallows (http://en.wikipedia.org/wiki/Cave_of_Swallows) is 55 meters across, while the pit on Mars is around 150 meters across. Cave of Swallows is around 350 meters deep.

RGClark
2007-Aug-30, 02:49 PM
Hi all,
I seem to recall someone posting an article here on finding northern analogues of the "black smokers" found near the south pole of Mars. The search function has not turned anything up, does anyone have any info on that find?

I though I had found some myself but they turned out to be rock ledges when I found the source and turned it upside down! Interpreting the images is a little more difficult than I had imagined. :) (see below)

You're referring to this discussion in the Space Exploration forum:

http://www.bautforum.com/space-exploration/62470-north-polar-geysers.html

By the way I've been informed that there are hundreds of the fan shaped deposits in the north polar region that might indicate deposits from geysers.

These deposits are seen in association with north polar dunes. Here's a list of MOC images showing north polar dunes:

MOC Images of North Polar Dunes.
http://www.markus-harder.de/dunes.html

There are over 1,500 in this list, not all of them showing the fan shaped deposits. I wanted to see if any of these that show the fan deposits were in the 68N to 75N latitude range of allowable Phoenix landing sites. Then Phoenix might be able to land nearby to see if the "geysers", or whatever they are, are currently forming.
You have to look at these MOC images at the highest resolution available to determine if the fan shaped deposits are present, a pretty time consuming task. As a further clue to identifying them they seem to have the crests of dunes as their origin point.
I would like to ask anyone who's interested to take a shot at identifying some. Perhaps choose 20 to 30 of the images to search. How many of these show the fan shaped deposits? Do they always originate at the crests of dunes?
The ones in the 68N to 75N latitude band would have the highest priority, since they might usable for a Phoenix landing site. But make a note of any you find since it could be ones outside of that latitude band that are still active.


Bob Clark

RGClark
2007-Sep-01, 05:44 PM
On the HIRISE site, I did a search on the word "geysers":

http://hirise.lpl.arizona.edu/apotelesmata.php?q=geysers&order=release_date&submit=Search

and on the word "geyser":

http://hirise.lpl.arizona.edu/apotelesmata.php?q=geyser&order=release_date&submit=Search

These give a different count for the number of images so you might want to look at both of these lists. All or most of these are in the southern polar region. I don't know if any north polar ones are given.

BTW, here's a list of previously unreleased HIRISE images:

HiRISE | PDS Image Release: August 2007.
29 August 2007: HiRISE has just released another set of data to the Planetary Data System, which we’ve grouped here. These are images that have been previously unreleased through our Web site, and are now part of our catalog.
http://hirise.lpl.arizona.edu/pds_release_aug_07.php?page=1

Bob Clark

thothicabob
2007-Sep-01, 07:31 PM
Today's news is that one, maybe all, are vertical pits, not caves. See article in topic Caves spotted on Mars (http://www.bautforum.com/1060805-post52.html). They are deep-ish, 80 meters maybe in the one imaged, but not as deep as a cave might have been.

Earth's Cave of Swallows (http://en.wikipedia.org/wiki/Cave_of_Swallows) is 55 meters across, while the pit on Mars is around 150 meters across. Cave of Swallows is around 350 meters deep.

I got the news and what it was saying - I am just wondering if perhaps, at least in some cases, they are not ALL vertical pits. Looking at the picture I linked to previously, I can easily picture a large underground void beginning at about 80-100m below the surface; part of the roof collapes or gets penetrated somehow; there'd be a "hole" in the roof (essentially a "skylight") and it would look quite simiar to the picture - the border of the hole would have some thickness, as shown, and the light from the sun shining at an angle on the floor of the void, say 200-300m further down, would illuminate the edges of the hole and be partially blocked, with the illuminated area of the floor 'offset' in relation to the angle of the sunlight coming in, which seems to be the case in that picture.

Looking closely at it, anyway, that's at least one interpretation I can see. I am not 'certain', from *that picture* at least, that the bottom you see is only the bottom of a relatively shallow vertical pit and not the floor of a larger, deeper void or cavern.

Anyway, it may well be they are only vertical pits; I just don't "want" to discard the idea of them being skylights (in a sense) at the top of underground voids quite SO quickly, is all. And yeah, I know, science is science and what 'we want' is irrelevant - nature is what it is, period. Still, I think the possibility still exists, and at least that particular image - in my view - not only doesn't seem to rule it out, but seems to support it.

That's all. :)

OOPS: http://www.physorg.com/news107789000.html - here's the image i was talking about (different one above, i think). sorry!