The crater on the rim of Victoria crater on the right side of this
image very definitely gives the impression of a volcanic crater rather
than an impact crater:
Victoria Crater on Mars.
http://antwrp.gsfc.nasa.gov/apod/ap061002.html
An analogue of the Victoria crater complex might be Crater Lake,
Oregon:

Crater Lake, Oregon
Crater Lake National Park
http://vulcan.wr.usgs.gov/Volcanoes/...framework.html

A curious aspect of Victoria crater is its irregular rim with
alternating promontories and alcoves. The rim of Crater Lake, Oregon
might be analogous to this:

Crater Lake, Oregon.
http://earthobservatory.nasa.gov/New...3?img_id=17401

Although in the case of Crater Lake, the irregular rim is only
apparent on half of the rim, the other half having a more rounded
appearance.
The volcanic crater on the rim of Victoria might be analogous to
Wizard Island and Mount Scott in the Crater Lake complex, labeled in
the preceding image.
The crater forming Crater Lake formed from the collapse of a volcano.
Then an analogous scenario would account for the origin of Victoria
crater on Mars. Then Victoria itself might be a volcanic crater.
Then these two craters might give us a chance for the first time to
observe the interior of a volcanic crater on Mars.


Bob Clark

If you look it carefully, you see it is actually a dune, not a cinder cone. See for example this recent Opportunity route map. No craters to the left from Sol 952 position. The dark spot in the orbital image is obviously the pile of rock (fresh crater?) visible in the image. Cabo Frio is the tall cliff.

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This is a most interesting feature.

It is definitely a hole, walled by bedrock and very steep sided. There is no rim as such and it appears completely separate from Victoria crater in both MOC and rover imager.

The bedrock forms the faint white ring in the MOC image. We can't see the floor in the rover image but presumably is floored by the usual dark sand, making the dark spot in the MOC image.

The most interesting feature for me is the fact that the hole appears younger than the dune on the rim of Victoria crater. The dune is truncated by the hole, showing a near vertical section through the dune. The fact that the dune material support such a near vertical surface shows that the dune is very cohesive, perhaps indurated. The internal structure of the dune is clearly visible.

I don't think this is a volcanic crater. The lack of rim argues against a very recent volcanic feature and there is no other evidence of recent volcanism. The basaltic component to the and is a regional feature and can't be readily related to such a loal feature.

It does not look like an impact feature either. It's morphology is wrong. The walls are too steep and such a young (post dune) crater would have a rim. An eroded crater might lose its rim and even steep walls but would be much more shallow.

It looks like a collapse feature to me. the question is, what made the cavity the surface has collapsed into, and when? I hope the rover takes a closer look.

Jon

An interesting feature, but it looks as if they are moving away from it. What I've been waiting to get a close look at is the dark streaks coming out of a couple of bays at the top of the route map Nunu linked to. Probably just dark sand funneled by the wind through the bays, but still, I'd like to take a look at it.

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This crater is surrounded by interesting features. The talk at the UMSL forum is that they are moving over to the tallest of these features to get a nice panorama before sitting idle for a while, while Mars communication is limited by the Sun being between Earth and Mars.

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Opportunity is going to be at Victoria for a very long time. I'm sure they're going to take a good look at everything in the area that's worth taking a good look at. Don't jump to conclusions from short-term movements. I'd be willing to bet that we're still going to be here next October.

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Getting to the nearby highest point of the rim and thinking about it for a while is a good approach.

Jon

At the rate these rovers are going, they might meet up with the next-gen rover.

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@JonClarke
Hum,
This is part of a file image of Cape Frio that was taken by the Opportunity rover on September 28, 2006 (Sol 952).

My untrained eye sees nothing strange here.

Attached Images

Cape Frio sol952.jpg (72.5 KB, 26 views)

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Very nice, thank you. I attach an annotated version to try and explain the points I was making.

Jon

Attached Images

Picture2.jpg (127.7 KB, 39 views)

Have you seen the MRO image that shows Oppy on the rim of Vicky? If I'm looking at your crater, it looks like a secondary impact crater to me.

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I'd like to take a closer look at those too. Squyres suggested it might take 3 to 9 months to circumnavigate the crater. Then given the distance around the crater of the large streaks from Opportunity, it might take a month to get to those.
A particular flow of the dark material down the slope of Victoria might also be interesting to look at. It's much closer. It appears just below the label "Duck Bay" in this labeled image:

http://hiroc.lpl.arizona.edu/images/...not.browse.jpg

It actually looks like two flows that merged. But both seem to have very localized originating points. Then it might indicate some material that originated subsurface.


Bob Clark

Hard to tell which feature it is from the HIRISE image. Perhaps it is the roundish feature near the rim that appears below the "Duck Bay" label in this image:

http://www.newscientistspace.com/dat...0247-1_600.jpg

The MER scientists did refer to the small rim crater that appears in the APOD image in the Friday news conference. They gave it the name "Sputnik". It's mentioned about 19 minutes into the news conference which can be viewed here:

Mars Rover News Briefing.
http://space-multimedia.6x.to/


Bob Clark

Sputnik (the rubble-filled hole, not the sand dune behind it):

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It appears that "roundish" feature is indeed the rim crater "Sputnik". In the labeled image there are rover tracks that approach rather near it. So it was probably imaged when the rover was at this location.
Jim Bell during the news conference said the crater was within 20 meters, so probably could be reached in a day.


Bob Clark

Yes, the hole looks outrageously deep and steep when you look at the stereo image with 3-D glasses!

Layers of 'Cabo Frio' in 'Victoria Crater' (Stereo)
"This view of "Victoria crater" is looking southeast from "Duck Bay" towards the dramatic promontory called "Cabo Frio." The small crater in the right foreground, informally known as "Sputnik", is about 20 meters (about 65 feet) away from the rover, the tip of the spectacular, layered, Cabo Frio promontory itself is about 200 meters (about 650 feet) away from the rover, and the exposed rock layers are about 15 meters (about 50 feet) tall. This is a red-blue stereo anaglyph generated from images taken by the panoramic camera (Pancam) on NASA's Mars Exploration Rover Opportunity during the rover's 952nd sol, or Martian day, (Sept. 28, 2006) using the camera's 430-nanometer filters."
http://marsrovers.nasa.gov/gallery/p...88_L7R1ana.jpg


Bob Clark

May be an expanasion of the main crater has been close by a dune ?

In the friday, Oct. 6 news conference on the MER rovers, there was mentioned a linear feature in Victoria crater that may be a dike.
It's mentioned about 10 1/2 minutes into the briefing during a simulated fly-over of the rim of the crater.

Mars Rover News Briefing.
http://www.space-multimedia.nl.eu.or...k=view&id=1055

Here's an image of it posted to the Unmannedspaceflight.com board:

http://www.unmannedspaceflight.com/i...e=post&id=7998

A dike is a solidified portion of lava that protrudes into softer rock. It becomes visible when the softer rock erodes away. There are many examples of dikes in Crater Lake, as with other collapsed volcanic craters.

Phanton Ship dike in Crater Lake.
http://www.billgass.com/Crater%20Lak...s/image004.jpg
Crater Lake.
http://www.billgass.com/Crater%20Lake.htm


Crater Lake and Phantom Ship; Crater Lake National Park, Oregon.
http://www.viewfindersnw.com/photos/pnbf102.jpg
http://www.viewfindersnw.com/?image=pnbf102


If this feature, is a dike that would support the idea that Victoria crater is a collapsed volcanic crater.


Bob Clark

Hum,
while it is possible the more likely scenario (IMHO) is that the crater is a very ancient impact crater that has been eroded down and excavated leaving no trace of the ejecta, or original crater walls.
The `sedimentary` layers on the surface that overly the broken `gabbros` or breccias indicate the whole region was covered with water (or experienced the same process) that created the deeper layered formations seen in the crater wall formations.
The source of the breccias however maybe of volcanic in origin (or the eroded impact ejeca).

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I see no evidence as yet for Victoria being an ancient crater that is synchronous with the sediments, rather a much younger though eroded crater.

Regarding Sputnik, from the HiRISE imagery I now think that is is mostly likely an impact feature.

Or maybe it is a crater of a asteroid far in the past i think.

Hum,
if the thick layer of gabbros turn out to be eroded impact ejecta, which is sandwiched between layers of `sediments`, the top most which can be seen on the surface, then that must mean that that top layer is young too.

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Jon, the shape of the hole looks stange to me. Both in the 3-D image and in the HIRISE close-ups it looks more like a gash than a circular hole. See for instance this blow-up posted to Uplink.space.com:

http://uplink.space.com/attachments/...nnot.bro.5.jpg


Bob Clark

These Microscopic Imager images were posted to Uplink.space.com and MarkCarey.com/Mars/

http://uplink.space.com/attachments/...OP2936M2M1.jpg

http://static.flickr.com/87/26541791...3bdba5.jpg?v=0

It has the look of vesicular basalt, or perhaps an ignimbrite, which is formed of compacted volcanic ash:

Image:Ignimbrite.jpg
http://en.wikipedia.org/wiki/Image:Ignimbrite.jpg


Bob Clark

Sputnik resembles Fram crater which Opportunity studied before arriving to Endurance.

__________________
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Same feeling , looks more like a gnash. May it is because of erosion and everything has been levelled ?

*sigh* What wouldn't you give to be able to have a team of geologist Astronauts there instead.....

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Enter the World of Athran

What evidence do you have for gabbro or even breccia?

Jon

Thanks for the link Bob. With the high resolution image I must say what I thought was internal stratifiction in the dune was in fact bedrock. This, and the circular profile in the HiRIOSE image is what has made be think this is another small impact crater.

What is interesting is the fact that the sedments have a destinct dip towards the crater and that there is a bedrock high under the dune, possibly allowing the dune to form in the first place.

Jon

I know, I know. A day to walk round the exterior and interior of the crater, a day logging and sampling the walls, a couple of days coring the infill and then off to the big crater, just an hour or so's drive away.

I give about 8 hours a week towards that goal. Any more and it would be grounds for divorce I suspect, unless I got paid to do it

Jon