Thing is - everyone will have evolving theories on what we're seing. To say "MAKE CHOICE NOW" is a bit harsh - and not how this sort of thing should work really.

Doug

If this were on Earth, I would suspect it to be a mirage. Can the atmospheric condition (temperature inversion) responsible for mirages on Earth occur on Mars? More to the point, can localized heating occur on Mars to change the refractive index of a layer of atmosphere sufficiently as to enable a mirage?

Conditions to produce a mirage (if such can occur on Mars) are temporal, whereas the images from Opportunity are from different times during the Sol. The object appears to be there on all images, so it is not likely to be a mirage for this reason alone.

What may be interesting is the contrast between the object and the ground / background at different times of the Sol, i.e., does the contrast change with the lighting phase angle?

As to which side I am watching this game from, it would be the near side because Opportunity is approaching from the near side.

From the link above I've made a list of places where Victoria had passed, there are some who would sound great for an alien world landscape...

Zebu
Seville; Tenerife; Cape Verde; Brazil; Cabo-Frio; Rio de Janeiro; River of St. Christopher; Point St. Antony; Cape St. Apelonia; Shoals of the Currents; Island of St. Matthew; Bay of Labors; Port of St. Julian; Santa Cruz; Cape of the Virgins; Thieves' Island; Phillippines; Island of Good Signs; Valley Without Peril; St. Lazarus; Macangor; Cabo Matam; Borneo; Carpyam; Caram; Dygua?am; Vay Palay Cucara Canbam; Bolyna; Bamdym; Islets of St. Paul; Mount St. Paul; Island of the Myrolobans; Port St. Mary of August; Quipe; Tamgym; Maluco; Tydor; Targatell; Ternate; Timor; Betachina; Porquenampello; Cape of Palms; Quimar; Camarfya Charam; Islands of St. Antony; Cyco; Quamgragam; Pamo; Camafo; Geilolo

The first one, Zebu, is where is thought Magellan to have been killed, the other ones follow the vessel route.
It would be nice to see Opportunity start the journey around Victoria where the navigator ceased...
First stop: Zebu!

Two questions have, so far, gone unanswered. 1. Why is Beacon so bright and, apparently, so tall? and 2. Why is it so much brighter than its surroundings?

Just wondering...

Is it possible that - assuming it was formed AFTER Victoria, and no-one's answered me on that yet - the Beacon is an unusually long and smooth piece of ejecta, which landed there after the formation of the little crater on the south of Victoria itself ("Sofi's Crater" someone called it)? Kind of a shard of some sort, or an unusually large "shatter cone", such as we see at Meteor Crater and other craters?

Think back to the slabs we saw in the wall of Burns Cliff back in Endurance ("aaah, the good old days...!"). Now imagine some of those being unearthed and scattering around after an impact. Might one of them ended up oriented vertically?

Just a thought... we've seen some pretty tall, pretty sharp rocks on our travels. This might just be the tallest, sharpest yet, I'm thinking...

Stu,

We can see some land slides in other part of VC. The brigthness of the Beacon could be may be explained if it's a rocks that has been unearthed (unmarsed?) "recently".

Edit : well, finaly I decided to writte something more than just "Stu"

Stu,

What?!?!?!

Wow, talk about keeping a guy in suspense...!!

The brigthness of the Beacon could be may be explained if it's a rocks than has been unearthed (unmarsed?) "recently".

Maybe I missed something, but don't the images taken so far show the Beacon is taller than the surrounding terrain? I can't see anything "above" it. So did the rocks slide down then go into reverse and build a cairn?

[quote name='Stu' date='May 19 2006, 12:19 PM' post='54889']
[[i]The brigthness of the Beacon could be may be explained if it's a rocks than has been unearthed (unmarsed?) "recently".
Maybe I missed something, but don't the images taken so far show the Beacon is [i]taller than the surrounding terrain? I can't see anything "above" it. So did the rocks slide down then go into reverse and build a cairn? [/i]


It's were I see that my english it's not sufficient sometimes. I was meaning (and mining too) that a part of the "peak" that constitute Beacon collapsed "recently" and that what we see now is the bright part that has been unearthed.

Stu:

I don't think you'd find a shatter cone in the overturned ejecta blanket. It may be that we're seeing a discrete lump of rock here, but my money is rather more on a rounded mound which just catches the light. If so, then we may expect it to dim considerably as we get closer.

Bob Shaw

Opportunity Presses On Toward Victoria

http://www.spacedaily.com/reports/Opportun...d_Victoria.html

Pasadena CA (SPX) May 18, 2006 - NASA's Opportunity rover has driven about 200
more meters (656 feet) to put itself within about 1,100 meters (two-thirds of a
mile) of Victoria Crater, its next destination on the Meridiani Planum. As of
Martian sol 822, or 732 sols past its expected operational lifetime, the rover
still has shown no major mechanical or technical difficulties.

- Spirit Continues To Compile Panoramic Image

http://www.spacedaily.com/reports/Spirit_C...amic_Image.html

This is my interpretation of what we are seeing... using a truly grotesque stretch of the image.

I think there's a perfectly acceptably outcrop right there on the near rim which can be the beacon. Compare the point I indicate here with the new image from JPL in the last press release.

Phil

Yes...I'm playing on your team...I had placed it almost on the same spot.

http://www.unmannedspaceflight.com/index.p...indpost&p=54547

It's were I see that my english it's not sufficient sometimes. I was meaning (and mining too) that a part of the "peak" that constitute Beacon collapsed "recently" and that what we see now is the bright part that has been unearthed.

Ah, thanks climber, I'm with you now. Yes, that makes a lot of sense to me. Every time I look at images pf that Far Rim I am more convinced that Beacon is a raised feature, not just one side of an outcrop. I'm going to hang on to my "piece of ejecta" idea for a while longer yet...

Are my eyes just fooling me around or is the beacon (...And something aside...) appearing on this rear hazcam image?...

http://qt.exploratorium.edu/mars/opportuni...00P1311R0M1.JPG

A good weekend to everyone!

It's just your eyes fooling you, ustrax . I know how you feel though, it is hard to keep from seeing what you want to see.

Still with the "ejecta block" theory...

Here's a pic I found of the rim of Meteor Crater, where you can see lots of big ejecta blocks. Now, I haven't been there, so maybe someone who has could tell me if these are still where they originally landed, or if they were shoved and arranged there for aesthetic purposes...? If the former, then I still think it's at least possible that Beacon is a large ejecta block excavated by the formation impact of either VC itself or "Sofie's Crater".

Can't wait to find out just what the heck it is!

Nice pic, Stu. It shows the potential, but also the problem in the ejecta block idea. Namely there are "lots of big ejecta blocks", not just one. Of course, one block has to be biggest and last longest, and maybe that's Beacon, but we've been following its light for weeks now and not seen a flicker of other blocks scattered across the VC apron. How probable is that? That's why I'm favoring the idea of a dislodged slab of evaporite teetering on the rim (near rim) of VC. (If it were sticking up from the far rim it should have shrunk or disappeared by now.)

Thanks Shaka, some good feedback there, appreciate it. Logically, the near rim scenario makes more sense, I agree, but I guess the romantic in me is yearning for Beacon to be on the far rim, because that would be another thing leading us on, just like the Columbias led Spirit on, and Endurance drew Oppy out of Eagle... another light on the horizon, calling to us...

[quote name='Stu' date='May 19 2006, 10:09 PM' post='54994']
...the romantic in me is yearning for Beacon to be on the far rim, because that would be [i]another thing leading us on, just like the Columbias led Spirit on, and Endurance drew Oppy out of Eagle... another light on the horizon, calling to us... [/i]

I like what you say Stu. If poetry triumphs against nearimers, I realize that, if we enter VC by the boat ramp, we'll still be some 700 m away from the Beacon. That's quite a distance to get sharp pictures of it even if we'll know then where the light come from.

Stu:

Here's a 'Marsified' version of your Meteor Crater image!

I don't think we'll see anything like this view at Victoria. All the other craters we've seen have been highly weathered, with no ejecta to speak of - we've been looking at o-o-o-o-ld craters. Meteor Crater is almost historical, and simply isn't as eroded. What we may be seeing is one of the wasted-away 'tentacles' catching the light - I really don't expect there to be a nice big lump of rock acting like a totem...

Bob Shaw

LOVE the Marsified image, thanks Bob!

I don't think we'll see anything like that view at VC either, I was just using it to illustrate a remote possibility, exploring options, thassall. My #1 candidate is still a raised top on an outcrop, like the fossilised spine of some gnarled old martian dinosaur protruding from the duricrust, that makes much more sense. I just like the idea of a huge chunk of ejecta sitting there, calling out to us from across the crater...

I finaly was able to put my view of what we see using both Stu's image and Dilo's (I think) :

Click to view attachment

climber, are you real assuming that these two distant structures are almost superimposed?
this is not possible based on Oppy position, I believe...

[quote name='dilo' date='May 20 2006, 12:31 AM' post='55016']
climber, are you real assuming that these two distant structures are almost superimposed?
this is not possible based on Oppy position, I believe...

Dilo, if you consider that the "light" come from the brigth part of "1" (not the summit itself), it may still work. Edit : Last available pictures doesn't show the black feature anymore and this is consistent with last Oppy move a little bit East.

Climber:

Like I said, tentacles!

Aaaaaiii!

Bob Shaw

Climber:
Like I said, tentacles!
Aaaaaiii!
Bob Shaw

Bob, you may try some other words since I didn't get the meaning!
You can either be kind with me or make others to laugh by getting the situation worse

Climber:

You drew attention to the areas of Victoria which I described earlier as 'tentacles' - I then made the association with Cthulhu (Our Master Below, to whose terrible hunger I expect eventually to be sacrificed, and I therefore performed the usual ullulation).

Ask Bruce - it's a (sort of) joke. Maybe...

Bob Shaw

You drew attention to the areas of Victoria which I described earlier as 'tentacles' - I then made the association with Cthulhu (Our Master Below, to whose terrible hunger I expect eventually to be sacrificed, and I therefore performed the usual ullulation).
Ask Bruce - it's a (sort of) joke. Maybe...
Bob Shaw


Oh yeah, thanks, I've got it. Tentacles are sort of Hooligans of the Nearimer's

Er... ...possibly. Do they have big teeth?

Bob Shaw

At last, new Pancams from Oppy: http://qt.exploratorium.edu/mars/opportuni...00P2413L2M1.JPG

Corner Crater showing a few more details, and there's something else new: largish, white, angular cobbles scattered around, even high up on the sand ripples. Always something new from Mars' box of tricks. This is the sort of stuff I could interpret as proximal ejecta from a relatively recent, nearby impact. I'll be fascinated to see if it gets more abundant as we approach Corner Crater!

Here is a comparision between orbital and ground images, with some headings superimposed.
It's a "prettyfied" version of the one I made when standed with the near rim team (aka the "winner team" ), just adding the data from sol 823.

Last data is again consistent with the near rim position BUT don't jump to any conclusion yet. Given the current position, near and far rim options are on almost the same heading; any error on either the route map or on the pancam fov would change the headings in a way that any option would be the winner.

We should wait for the rover moving further south.

Click to view attachment Click to view attachment

Edited: Further looking to the pancam mosaic I've found what seems to be a small crater in sight. It's annotated in red on the (edited) images.

Ahh! The Brazilian Eagle strikes again!
How can we lose?

Well done, Tesheiner. Parallax still suggesting that near rim fits better, even if we still looking for some kind of absolute azimuth, because scale is critical here!
Anyway, this is a registax-stacked beacon image of Sol823 (I'm putting the complete stitch including Corner crater is on the other 'proper' thread):
Click to view attachment
You can choose the version you like more (I reccomend to use the first one if you want to make further processing!).
It seems we have two beacons here, but I suspect this effect is due only to particular light conditions. In alternative, the smaller right portion is a new bright feature and I have impression that we start to see also other small, bright points all around! (to be confirmed),

I'm thinking that when we'll be on the edge of VC, the far rim will be some 730m away. I said to myself that it'll be nice to know how much details we can see from this distance but, there is nothing as big as what we're gona see once at VC, in Meridianii, that we already sew from that far... but there is in Gusev.
I took this known pictures and tried to draw a circle of 730m from where Spirit is now and, as you'll see, I ended up nearly to Husband hill summit.
Click to view attachment
So, now we can compare the details we see now on well known feature on the hills (or closer) to what we'll see in VC.
I may be had a good idea but I must make some progress with Photoshop. How to draw a circle without the fill-in colour ? If somebody can do it right, I'll appreciate too!

1. Use the elliptical marquee tool
2. Draw the circle by holding down the shift key
3. Menu: Select,modify,border
4. Set the border to a small number of pixels
5. Now you can fill this border with any color you like (Edit, fill)
or put it in a seperate layer (ctrl-j) and do all sort of things...

Have fun!

Just a thought...

Here we have Corner Crater with its visible bright rim, there we have Victoria with its near rim and just a little beacon on it (on the near rim of course! ). But why don't we see a whole collection of outcrops?

Could it be that the exact rim is *still* behind the horizon, and what we are seeing *at* the horizon is still part of the ejecta blanket? In this scenario, only the highest outcrops at the near rim (read "beacon") would be visible and it would explain the lack of other visible features. Comments, opinions?

[quote name='Cugel' date='May 20 2006, 12:39 PM' post='55064']
Have fun!

Thanks Cugel! Anyway I'm not still able to draw the circle : it keeps to be filled with a lot of nice colours but I just want to drawn a circle!
Anyway, I drew it by hand and realize that VC will fit nicely in the heart of South Husband hill :
Click to view attachment


PS :Sorry Tesheinier not trying to answer to your new idea, but, I'm sure you'll understand that if I'm not able to draw a circle, I can't be of any help to think about such revolutionary theory of yours

I'd suspect that all you bneed to do is to set your background color to "Transparent".

Tesheiner, everything is at such _low_ relief we are not seeing into Victoria, so your idea has merit.

--Bill

Try edit,stroke instead of edit,fill after drawing the circel with the selection tool.
Still, your hand drawn circle is nothing to be ashamed of....

Climber:

Just use Windows Paint to draw your circle! Oh, and if you use Paint the file sizes are smaller than with Photoshop, too - up to about half the size in some cases.

Bob Shaw

Climber: another method! You have the background image. Create a new layer for the circle. Use the ellipse tool plus shift key to make a perfect circle, and drag out a circle the size you want. Use the paint tool to fill that circular selection. Now use select-modify-contract and enter a number of pixels (say 5 to start, use trial and error to get what you need)... the selection shrinks inside the rim of your circle. Now use 'edit-cut' or just 'backspace' to clear the new selection.

This "contract, then cut" method works for selections of any shape. You can outline an area with the polygon tool, paint it, contract, cut - you get your outline.

Phil

orrrr... select your area - then go select->modify->border and put in 5 or so, and fill the selection it leaves you with

Doug

climber said:
"PS :Sorry Tesheinier... if I'm not able to draw a circle, I can't be of any help to think about such revolutionary theory of yours."

I heard that Albert Einstein could not tie his shoes.





So we all may be winners! Or at least claim to be.

If more beacons pop up, some on the near side, some on the far, keeping a eye on the original may be like playing a game of three card monte.

Good idea Climber. The top of Husband Hill would make a good substitute for the rim of Victoria, although I believe it's higher than Victoria's rim.
View of Inner Basin from Husband Hill, green line shows where rim of Victoria Crater would be.
Click to view attachment
Edit: here is a single frame, full size to give an idea of how much detail could be visible on the far rim
Click to view attachment

This is certainly possible, Tesh. You are implying that the immediate rim zone "sags" into the crater, perhaps due to wind erosion undermining the rim edge. A certain degree of this may be inevitable in an old, very eroded crater, especially when the edge consists of a 'soft', weak rock like the evaporite. Everywhere we look this stuff is cracked and fractured. It's closer to piecrust than granite.
I'm not yet convinced that the apron we are seeing is "the ejecta blanket" of VC, but I admit the shards of (presumably) evaporite we are starting to see scattered across the ripples may be real ejecta. They're much more likely to be from a fresh crater like Corner, however.

For the time being we can't really see the crater, but here below is an attempt to put VC (taken from MOC images) in a sort of "perspective mode" and combined together with the last pancam mosaic (sol 823). The headings on both images should be correlative.

Click to view attachment (423k)

Alan,

That's REALLY useful, thanks! Got a much clearer idea now of just what we'll be able to see from the rim when Oppy reaches her goal. Thanks!

Wow, the things we're going to see soon... anyone else starting to get the same shivery feeling we had as we edged towards Endurance?

True! Imagine a 360 pan that features mostly one giant hole, the far side of which is still feature-indistinct, and we can’t wait to get to the far side, just to prove what we think we see... a possible route into the chaos of an abyss.

I don't know if anyone has considered that the pancam image scale should vary across the field of view, and also generally the scale will vary when measured in different directions at the same part of a frame. This sort of geometrical distortion will generally increase with the field of view of a lens, so navcam and especially hazcams will be worse, but even pancam will exhibit it to some extent. So perhaps some figures we see for pancam give the image scale at the centre of the frame while others give the average image scale or the actual field of view of a full frame.

Also, some of the pds calibrated images are geometrically corrected, no? This would presumably bear on the question and likely change the image scale over the field of view.

Fred.

I believe that's correct. It's 0.28 mrad/pixel at the center for pancams.

Stepping into the near/far beacon debate, it seems to me we have good reasons to doubt both options. A beacon on the near rim seems unlikely because it would be very unique - there is no sign of other boulders/outcrops of similar size on the near rim (though possibly smaller ones). Also there is no obvious target on the near rim in the orbital imagery, although at 1/2 to 1 metre in size, it's not clear we should expect to resolve it from orbit.

The far rim interpretation seems unlikely because it would mean we just happen to be seeing a pixel or two of the tip of a "promontory". The alignment has to be very precise for this to happen - it would surely be much more likely to see either nothing or a lot of the promontory. Also, we have the parallax measurements from members of this forum supporting a near beacon.

Of course it has to be one of these two choices. If I were actually standing there beside Oppy, I could settle this easily. Taking the beacon height to be 2 pixels, that translates to about one metre at the far rim distance. We are about twice as far from the near rim as the near to far rim distance (roughly 1200 vs. 600 metres). This means that if the beacon is on the far rim, if we dropped to the ground, and hence lowered our viewpoint by two metres or so, the beacon would be covered (or nearly so) by the near rim. This would not happen if the beacon were near. This is just a parallax effect, but much more efficient than a horizontal one.

Pancam has a fixed height. But the rover is moving. If Oppy were to drop by a couple metres below its current line of sight to the beacon, the beacon will disappear if it's on the far rim. Unfortunately, the land here is very flat. Looking at the west slope of Victoria, the highest part of the rim is only 4 or 5 metres above the plain. Towards the east the land appears to drop. If we drop enough en route to Victoria, we may see the beacon disappear if it's on the far rim.

To sum up, because we're headed towards Victoria, horizontal parallax isn't very effective at resolving this. But if we drop (or rise) by only a couple of metres, our view of the beacon will change dramatically if it's far, but not if it's near. This may be our best bet to settle this... until we actually get there, of course!

Fred.