Tiny Craters Options

[atomoid]

Actually didnt we see the first crater about halfway between endurance and purgatory?, but alas, the number of them have certainly been increasing in frequency.

As for a renewable ice source, seasonal atmospheric or ground-originated water vapor condensing to frost on the lee side of dunes, building up into dusty nodules and getting buried by migrating sand seems a simple scenario, and would explain the increasing number of them as we near victoria, implying that were reaching an area of greater local ground vapor release...

if this scenario works, i'd expect many existing analogs on Earth, which shoudl be more favorable to this process. anyone aware of any similar phenomemon?

[Guest_paulanderson_*]

A sapping process caused by ground cracks opening up seasonally is unlikely, because this should preferentially cause microcraters (especially larger microcraters) in areas where the dunes are thin - such as in the sands of the valleys between the dunes.

So the sapping process has to be renewable, and not caused by cracks in the bedrock.  This is the reasoning that led to my hypotheses that subliming or melting ice nodules is the origin of the sapping process, which then causes the microcraters.  Now the difficulty is explaining how the ice nodules are renewable, and how these ice nodules came to form within the dunes.

Perhaps the ice nodules originate from upwellings of brines from pores or channels the bedrock.  Or perhaps, the the dunes contain fossil ices from depositions which occured when Mars has a greater axial tilt.  I don't know.  But I would certainly like to see a discussion of how ice might enter a dune!

I thought I noticed one between dunes a few sols ago (but after that good one on sol 616); I'll have to go and find it again though.

If, as the pevious BBC article indicated, there is evidence for ice within Martian dunes, at least larger ones, perhaps it could happen here also in these ones? I like the ice nodules / sapping theory. I was sure initially they were from impacts also, since they looked like it and then JPL said they were, so they must be then, right?... They still could be, I'm just questioning that idea more now.

Re CosmicRocker's comment about going through previous Oppy images, I'm willing to do that as much as I can, if it helps. These micro-crater things have piqued my curiosity.

I also noted, as mentioned a while ago, that they do seem to be more common in drifts close to bedrock, at least that is the impression I get. I can't recall offhand seeing as many yet in dunes away from bedrock areas (except those two first ones back in April were I think).

[Bob Shaw]

Actually didnt we see the first crater about halfway between endurance and purgatory?, but alas, the number of them have certainly been increasing in frequency.

As for a renewable ice source, seasonal atmospheric or ground-originated water vapor condensing to frost on the lee side of dunes, building up into dusty nodules and getting buried by migrating sand seems a simple scenario, and would explain the increasing number of them as we near victoria, implying that were reaching an area of greater local ground vapor release...

if this scenario works, i'd expect many existing analogs on Earth, which shoudl be more favorable to this process. anyone aware of any similar phenomemon?

On a much larger scale (say 30m across), you do get ice-heave features in permafrost which can cause what look like mini-volcanoes, often with little ponds in the centre - these features are called 'pingoes'...

Bob Shaw

[Bob Shaw]

See also:

http://www.unmannedspaceflight.com/index.p...240&#entry25382

Bob Shaw

[Guest_Myran_*]

Bob Shaw said On a much larger scale (say 30m across), you do get ice-heave features in permafrost which can cause what look like mini-volcanoes, often with little ponds in the centre - these features are called 'pingoes'...

Yes im very familiar with those, we got plenty, was about to say that they can be somewhat larger but you are quite right saying they are 30m on average.
These are among many things I've been on the lookout for in the rover images. So far I havnt seen any. So my conclusion have been that any possible subsurface ice are long gone and any 'pingoes' filled in by drifting sand, or alternatively its too deep down to cause any such features.

[atomoid]

heres a giant tiny crater, that Dilo poseted in another thread,
reposting it in this thread for further investigation...

Interesting zigzag cracks in the foreground (sand-sorting along the faults due to vibration effects from the impact? if so, then we could infer something intersting about the local seismic characteristics)

sol 649!

cant seem to link the image itself so heres the link to the image

[silylene]

heres a giant tiny crater, that dilo poseted in another thread,
reposting it in this thread for further investigation...

note the zigzag cracks in the foreground (effects of sand-sorting along the faults from vibration effects from the impact?)
cant seem to link the image itself so
heres the link

That's an interesting photo!

I see the larger crater, and two possible microcraters, the zig zag, and what looks like several minor slump on the closest dune.

[RNeuhaus]

It seems like that zone has an unstable underground. (cracks, zig-zag, hole).

Rodolfo

[silylene]

The Ultreya area in Gusev has some good dune fields which should be good substrates for showing microcraters (assuming microcraters are formed by impacts). I wonder if we will find any of the enigmatic microcraters there?

Overhead view (vertically stretched 4x, from Ultrax):
http://i16.photobucket.com/albums/b14/ustrax3/4x.jpg

Side view:
http://www.unmannedspaceflight.com/index.p...pe=post&id=1354

[dilo]

Hey, I'm wondering how dark (deep?) is this small, round hole viewed by MI camera on Sol 649! I this this kind of hole can create minicrates (as the wind cover it with fresh sands)... any theory on the origin?

Attached thumbnail(s)

 

[helvick]

Hey, I'm wondering how dark (deep?) is this small, round hole viewed by MI camera on Sol 649! I this this kind of hole can create minicrates (as the wind cover it with fresh sands)... any theory on the origin?

See the other thread on Mogollon MI's - it was almost certainly caused by the MI Contact Sensor as explained in Dot.dk's post.

[edstrick]

You *SURE* it isn't caused by baby sandworms?....
Where's the Harkonens when we need them....

[OWW]

You *SURE* it isn't caused by baby sandworms?....

Eureka! Sandtrout. That's the answer. Read this:

http://en.wikipedia.org/wiki/Sandtrout

Sandtrout are drawn to water in the open desert and together multiple sandtrout will gather to encapsulate water, creating deserts safe for the adult worms

So that's what happened to the water on Mars!

Eventually, [...] a build up of gasses that cause an eruption of the pre-spice mass, blasting out Carbon Dioxide gas

And that's where all that CO2 came from! The tiny craters are CO2 vents!!!!

The water evaporates leaving behind dried spice

Oppy's found spice deposits!

[atomoid]

Spotter control... no sign of the carryall...
Damn it... Harkonnens.
Spice! ... pure unrefined spice!
Damn the spice! Get out of there.

[edstrick]

D'oh!
If Oppy suddenly goes silent, and Mars Recon orbiter spots a fresh minicrater where it was last heard from.....
We'll know why!