Actually, maybe not. The dark corona often fades very quickly as dust covers it.

http://tinyurl.com/yksr3do for some MOC re-imaging of sites

Great example. I was wondering that myself.

This HiRISE image: PSP_008196_1825_RED - shows the same crater in 2008, not fully faded yet.

Phil

That's pretty dramatic.

Just out of curiosity, do we have any idea if the rate of surface dust deposition is globally constant or regionalized? Reason I ask is that Meridiani is itself a large albedo feature, and it seems that dark=not as dusty, at least based on fresh crater ejecta observed thus far.

Weren't we supposed to see a drive just on Monday?
looks like Oppy is dancing around the totem...

EDITED: How I would like to see a replay of Marquette making its way here...

I'd say wandering around... but, it' s what I'd do in a... "market" place

LOL'ing at EGD's Post #594

Should be able to ballpark the local deposition rate by examining Oppy's tracks -- which IIUC are fading already.

Correct me if I am wrong, but isn't the fractured face of Marquette one of the freshest-looking we've seen on Mars? I.e., it doesn't look as if it's been sandblasted. And if so, one would think that it would be an irresistible target for the microscopic imager . . .

My main reason for being sceptical that "fresh crater" is a very recent impact is that the odds have got to be extremely slim of finding one. The link you gave gives an estimate of the current cratering rate on Mars: 3-6 x 10^-8 craters/sq km/yr. So an area of 10 sq km around Oppy's track should've had around 3-6 x 10^-6 new craters in the past decade. In other words the odds are between 1-in-100 000 and 1-in-a-million.

Turning this around, I guess this means that the freshest crater in the 10 sq km around Oppy probably happened something like a million years ago.

But definitely "fresh crater" is one of the freshest, if not the freshest we've seen, so I'm really looking forward to visiting it...

Kind of like, oh, hitting a hole in one at a hundred million miles.

You have a point, of course. But think positive.

That's for one year. If we use the MSS images linked above we can say that a crater might look "fresh" from orbit for 5 - 10 years, so chop your odds up again. But as someone noted Meridiani might have a different dust depositional rate, so maybe craters look fresh for 20-50 years (and that's assuming a fresh looking crater consists of fragmented rock with greater staying power than the rover wheel tracks). I also take issue with your 10 km(2) figure. I'd take into account the entire region between Eagle and Endurance as subject to close examination by keen eyes. The odds go way down then.

Actually my calculation was for 10 years. And I thought 10 sq km was pretty conservative for an area that close to Oppy's track. But even at 100 sq km the odds only go up one factor of 10 over what I posted, and we need 5 or 6 factors of 10 to get the odds near even...

The odds are low, but when you convert from probability to the real world, the answer is either 0 or 1 (excluding quantum phenomenon). Looks like Opportunity may be visiting an improbabily fresh crater!!! Another 1 where the probability sez .000001.

There is what seems to me a very "fresh" looking large crater to the northeast of Endurance, more or less the same distance from Eagle crater as Victoria. It's outside HiRise coverage but you can find it in the MOC images.

Click to view attachment

Oh my, wherever Marquette came from, I'm really loving the scenery:
http://qt.exploratorium.edu/mars/opportuni...PDP2582L7M1.JPG

Well, well, well...That is indeed an interesting member of the archipelago, isn't it? Definitely got some layers, but doesn't look much to me like anything else we've seen around here.

Looking forward to the MIs.

Assuming that the picture which Fredk has just posted is of the half of Marquette opposite the smoothly fractured side -- and taking a clue from Stu's invocation of "Wopmay" -- I would like to advance a theory, namely, that both Wopmay and the boulder of which Marquette is a piece started off life as big, normal-looking, relatively smooth-skinned rocks (themselves ejecta, or large fragments of collapsed crater wall); but that after perhaps billions of years of the peculiar kind of delicate sandblasting that occurs on the surface of Mars, they gained the rough, almost frothy surface which characterizes Wopmay, and which characterizes as well the parent of Marquette -- wherever it is; and that, further, Marquette was fairly recently broken off from the parent and left at its present position, where we can fortuitously see, on the broken face, what the "original" surface of the rock looked like.

All this by way of explanation of what has long been a mystery to me -- the almost hideous appearance of Wopmay.

And I am also guided in this theorizing by the sandblasting which surf shops sometimes do on driftwood to further enhance -- sometimes to a bizarre degree -- the grain of the wood.

Quick and dirty L2-R2 anaglyph of Marquette:
Click to view attachment

Very nice in colour now...

Click to view attachment

What a story it could tell.

We'll be there for quite some sols.
I guess we can still brush but can we still RAT?
The rock on the left side at the foot of Marquette that seams like starting to be cut in half would be of interest too for MI.

Here are my takes on Maquette Island :



Surprizingly interesting the dychotomy between the "eastside" and the "westside". Very probably, this rock is coming from Fresh Crater, with a part freshly exposed to the atmosphere, and a part exposed since a longer time. I think…
So, pretty interesting rock at all .

This is fascinating but I am still immensely enjoying the journey itself so here is a rough stitch of Sol 2058 Navcams (Sun 8th Nov). Love the tracks - so will work this up into a colourized panorama over the next couple of weeks as I get time between bush trips and journeys to Darwin.

Click to view attachment

But not so good to have heard that the front wheel current is elevated again. Although is great to have updates, it is frustrating not to know exactly how high the elevation is. Anyone got any more info on this?

Pretty, pretty rock...

Click to view attachment

Looks, to my untrained eye, like a shatter cone

Looks like it took one hard bounce on what is now the top. The top edge looks crunched and part of the upper surface looks abraded.

Either that or something hit it after it landed, knocking pieces off... lots of debris around it... http://twitpic.com/ovie8/full

Close-up of the big beastie here... http://twitpic.com/oveyt

Nice mosaic Stu, BUT, you still have a very pronounced vigneting

The surroundings of the same mosaic :

"BUT"?!?!?

Ant, the vignetting is deliberate... I just like the artistic look of it. I thought everyone here knew by now that I make unashamedly pretty chocolate box pics, and leave the scientifically accurate reference book pics to others.

Thanks a lot for the great colour views, all. Ant, there seems to be a problem with the two images in this post of yours - they don't load properly to the bottom of the frames.

Yes Stu, I already knew that, my "exclamation" was just a joke .

Fredk : Oh yes, there is a trouble in the two pics. I think this is the upload process who don't work properly. I will try to upload it again. Thanks for the observation, because most of the time, I check if the pics are correctly uploaded, and in this case, I forgot it.

Edit : done

It seems incredible to me that this relatively small rock is visible to MRO.

Rock = perhaps 60 x 30cm. Shadow at 3pm is about the same. Totaly surface involved, maybe influencing 4 HiRISE pixels.

I understand that the RAT is a cylinder of resin packed full of small diamonds.

If I remember rightly, Spirit's RAT had worn down to nothing after it had ground down "Peace" on SOL 373. Spirit's RAT had only enough resin to grind around 10 decent hard rocks.

Also from memory Opportunity had only ¼ of its resin left after it had ground several holes into the sides of Victoria crater. So far Opportunity has ground about 20 RAT holes. The reason that Opportunity’s RAT has lasted so much longer is that “Bounce” is the only hard rock that Opportunity has ground into.

I understand that when Opportunity reached "Heat Shield Rock" an attempt was made on Earth to grind a hole in an iron meteorite and ¼ of the resin in a RAT was used up in drilling that one hole. Unsurprisingly no attempt has been made to use Opportunity's RAT on any meteorite.

This means that I think that it is very unlikely that precious RAT resin will be used to drill a hole in "Maquette Island". I suspect that this rock is not a meteorite but is instead a block of basalt from elsewhere on Mars and so might only exhaust half of the remaining RAT resource. None the less I think that the RAT will be saved to drill holes in in-situ rocks in the hills surrounding Endeavour crater.

Re RAT:

As I recall, Opportunity's RAT had its brush bunged up, and there is at least one sensor problem. I think there are work-arounds in place, but it has been a while since I read about them. Perhaps one of the exalted "official ones" can enlighten us...

Not so much a cylinder - it's spinning bits with diamond tips that wear down.

Spirit seems to have done 16 grinds, the last being Sol 416 on a target called Watchtower.

Opportunity seems to have done 35 grinds so far.

http://www.honeybeerobotics.com/rat_log.html
http://nssdc.gsfc.nasa.gov/planetary/image...at_diagram2.jpg
http://nssdc.gsfc.nasa.gov/planetary/mission/mer/tb_rat.pdf

Basalt? Really? Aren't those sedimetary layers? It doesn't look that dissimilar from any other generic Meridiani bedrock to me The colouring's unusual; are there two distinct units? but my eyes keep interpreting the reddish material on the present top as the result of the impact. In the anaglyphs a "<" shaped scoring on the upper surface looks intuitively like a relatively low-velocity thump-down?

I do enjoy being wrong, it helps with filling in another little corner of my ignorance

If we assume that this little fragmentation is the prime impact spot of MI, then it looks strongly like it came just from the direction of fresh crater. Also because of "all" the debris around here that could originate from such an impact (trajectory) of MI.

When I look around the area using Ant's navcam panorama in this post, there seem to be cobbles/rubble on all the bedrock-level surface between the dunes for a large area around MI. So I don't think the localized patches of rubble are individual impact spots - they're just the lowest areas between the dunes. Instead it looks like a big rock, much bigger than MI, came down and shattered, scattering rubble pieces all around, and MI was the largest of the pieces.

For some reason the rubble isn't visible on the dunes. One possibility is it rolled off of the dune slopes, but I find it very surprizing that no cobbles managed to stay near the top of a dune. Another idea is that the rubble is everywhere on the bedrock but the dunes are covering the rubble beneath them. That surprizes me too since I thought the dunes were supposed to be ridiculously old. Any thoughts on this puzzle?

It would be cool to see a polar projection to get a better idea of the distribution of rubble around MI, and whether MI is near the centre of the rubble field.

"For some reason the rubble isn't visible on the dunes."

OK here goes. They land on the dunes too but the dunes swallow them up like quicksands, perhaps whilst momentarily fluidised by seismic shocks.

Yeah, that's what I've meant. A big(ger) rock that came down and shattered and left MI plus most of the other debris around here.

I guess (think) the debris field looks approximately fan-shaped. With this fragmentation as starting point.

I would be surprised if they used the RAT on an isolated rock here. While there is always the "use it while you can" argument, I would think the science team would prefer to reserve RAT resources for future sites where they can study rock strata in situ, where they have a much better chance of determining another part of Mars's geological record.

Your wish is my command!
Click to view attachment

Beat me to it. Here's a full equirectangular for sol 2058. I would convert it to a QTVR, but I seem to have lost that ability due to a software "upgrade"...

Noooooo!!!!!
I want my, I want my, I want my QTV.... um, R.

Say no more!

(About time I did something around here... I hope I got the x and y settings right!)

Sol 2058 3.2 mb QTVR file

Marquette doesn't look like a typical Meridiani rock to me. Besides, does anyone think they would stop to do a science campaign on a loose piece of the local bedrock? If this was a fragment of ejecta from the nearby "fresh crater," it is unlikely to be anything new, since that impact could have only excavated relatively shallow rocks. It seems more likely that this is either bedrock ejecta from a distant impact, or it is a meteorite fragment.

I look forward to seeing more imagery of Marquette, especially MIs. I am intrigued by paxdan's observation noting similarities to shatter cones.

Any science campaign here -- as already noted* -- could owe a lot to the necessity of giving the current-sucking wheel a rest. But Marquette does look different to me as well.

*"The right-front wheel is now showing a return of elevated motor currents. The plan ahead is to rest the actuator during an extended stop for an in-situ (contact) science campaign."

So, we'll have plenty of MI's of MI