> In fact it would take quite a feat of geometry to keep a far rim beacon just visible over the near rim all the raw from where it was first seen to now.

Just to remark this point, I think it's quite significative on this near/far rim game.

maybe we need to start a pool to determine the date when we will finally find out if its on near or far....

but then again some are already convinced...

[quote name='Tesheiner' date='Jun 16 2006, 04:15 PM' post='58661']
Just to remark this point, I think it's quite significative on this near/far rim game.

Ah ah ah, Tesheiner is giving up! He not longer uses scientifics arguments !!!!
Come on Farimers, one is down, let's "fight" to the others


Edit : Oups, I guess the word "geometry" is still kind of scientific stuff. Sorry Tesh

No, Tesheiner's argument - which was actually mine, is a simple bit of geometry. That is science.

Phil

... and some far-rimmers won't be until we are almost over it (at the near rim).

Now seriously (as much as possible ), my answer is: "next time they take a pancam mosaic with the beacon in the fov". It could be even after today's drive but more probably after this weekend once they reach the next "big" outcrop.

Well...
Quoting Mr. Squyres with all his solid scientific formation and talent de bien faire:

'I actually don't know where this feature is.'

Ever since he became a big-shot with a book tour, the guys in the know at JPL have been keeping Steve out of the loop, so this really isn't surprising.

Brian

uh-oh.... bad news for the far rimmers.... look who's hitched a ride along with Oppy:

[quote name='lyford' date='Jun 19 2006, 06:42 PM' post='58932']
uh-oh.... bad news for the far rimmers.... look who's hitched a ride along with Oppy: :

Ever since he became a big-shot with a book tour, the guys in the know at JPL have been keeping Steve out of the loop, so this really isn't surprising.

OK, that's an easy one, but still...

Comparison of Beacon feature on sol 848 and 855:



If the beacon is a near rim feature, then it should have increased in size about 11% between sol 848 and 855.

If it is a far rim feature, then it should have increased about 6% in size between sol 848 and 855.

I measure an increase in about 5%.

Ergo, it is on the far rim.

I welcome other measurments, but, in any event, in the coming sols the issue should be settled without question by the change in feature size.

For the rigurosity of measurements, shall you show how you got these numbers. What are the distances and angle have you measured from sol 848 and 855.

Rodolfo

You're assuming that the visible width of the structure remains the same wherever we are viewing it from. I'm not convinced this is true, given that we are dealing with features that are in some cases single pixels high.

Chris

The measurements of the Beacon size are still not really valid! I have measured the amount of pixels of the Beacon between the Sol 848 and 855: (0.13-0.14) versus (0.15-0.16) pixels with Photoshop which means an increase can vary according to the fine pulse movement

a=(0.16-0.13)*100/0.13 = 23.1%
b=(0.15-0.14)*100/0.14 = 7.1%

Conclusion, it is still difficult to measure the size of the Beacon height which has one milimeter. To count the number of pixels in one milimeter varies much due to very sensible movement variation.

Rodolfo

Er, I measured the width of a series of features around the beacon that increased from 77 to 81 pixels on 2x images.

To summarize, from sol 848 to 855 Opportunity moved 105 meters closer to Victoria. That means the distance to a near feature changed from 1035 to 930 meters and the distance to a far feature changed from 1735 to 1630 meters. These are changes in angular size of 11.3 % for near features and 6.4% for far features.

Thus a feature of, say, 100 pixels wide on sol 848 would have increased on sol 855 to 111 pixels on the near side, but only to 106 pixels on the far side.

The features I selected were from the far left of the "bright spot" to the far right of slightly bright spots just above the horizon. It is best to look at the stereo pair to make this judgement.

For me the best evidence was looking at the stereo pair after changing the size of the sol 855 image by 0.940% and 0.898% in Stereophoto Maker. The 0.898% change, corresponding to the beacon features on the far side, looked, um, subjectively better matched.

Of course, I could be just imagining I see matching features -- but I think the technique is valid.

Agree 100%.
My personal opinion is that those features are still too "fuzzy" to distinguish between a change of 5% or 10%, but the method is absolutely valid.

Add another 100% for me, Tesh. Still, Horton, both of us are genuinely impressed to see a Far-rimmer make any sort of measurement in support of his case. There might just be hope for the Sponge Patrol yet.

Er, actually I made measurments a month ago that supported the far rim hypothesis.

You may see the details in reply 227, 237 and 254 of the Victoria or Bust topic on the other blog.

There might just be hope for the Sponge Patrol yet.

Hope? Hope?? We don't need "hope", we have Gut Feeling! And we're not going to give up Far Rim Beacon without a fight that'll make the Battle of Serenity Valley look like a scrap in a school yard!!

Seriously, isn't this fascinating? I'll miss this banter when Beacon's actual location is confirmed.

Of course, I won't miss it as much as the Near Rimmers because I'll be celebrating...

I have already visited your posts in other forum.

I agree the method which depends upon to the trignometry using two Oppy transverse positions along with the base size measurement of Beacon. At that point, there is a problem since you measured two transverse point in a straight line to two Beacon positions (near and far rims). It is not true since Oppy between Sol 848 and 855 traveled more or less southwards so its route does not align to the beacon of far and near rim. The solution would be another angles of trignometry. You employed the technique of 2x vertical strech which simplifies the very fine measurements. However, the Beacon size still represents very few pixels and it need great precision or impossible to attaint it.

Anyway, your posts has incited our great interest on the dummy Beacon!

Rodolfo

I think you are confusing the geometry of referenced in reply 274 and the simple angular size change measurment used in sol 848-855 -- which works best when the motion is more or less towards the target.

The geometry referenced in reply 274 requires two colinear points towards the target and some transverse movement. The size change method requires two points perpendicular to the motion towards the target

I think my point was that both methods favor a far position for the beacon feature -- although the margin error is as large as the results -- at this point.

Perhaps there should be a pool as to when the issue will be resolved by a definitive measurment.

After reviewing the trigonometry of your reply 254, I admit it is correct. I was thinking with another type of trignometry tracing.

That is true.

At the Sol 848, the angle between near and far rim is approx. 4.77 degrees and the Sol 855, the angle between near and far rim has decreased to 4.06 degrees.
However, the angle between the Oppy position up to Beagle Creater and Near and Fear rim will decrease. I estimate the angle from BC to Near and Far rim would be around 2 degrees. Hence, the identification of Beacon will become more difficult until when Oppy starts to approach to Westwards or Southwards only to VC, the angle between Near and Far rim will start to increase and thus, the identification of Beacon will be clearer. Otherwise, if Oppy continues heading toward to Near rim, the angle will be between 1 and 2 degrees between Near and Far rim.

Click to view attachment

Rodolfo
P.D. I transformed the trigonometry drawing from PowerPoint to Jpg and the attach is on the post
I was not permited to upload the trigonometry graphic of measurements.
The msg error: Upload failed. You are not permitted to upload a file with that file extension.

Horton, let me add my voice to Tesheiner's sentiment that it's great to see others attempting a rigourous solution to this! (Even if I disagree with your result - well, heck, maybe it's even more fun when I disagree with your result!)

This reminds me of the time we tried to pin down Spirit's lander and parachute from atop Husband. I think it's so cool to be able to take these images, essentially live from Mars, ask a well-defined question that most would say couldn't be answered yet (what's the location of a curious feature), and then use geometry to go ahead and answer it (location: near rim! ).

Er, almost all of my original images are in PNG format. What browser are you using that does not support PNG format?

Good idea. I was thinking of that but in jpeg extension. I will do it at home.

Rodolfo

There are limits on the type of file that can be attached, but in terms of image formats...

JPG, JPEG, PNG, GIF, BMP and TIFF are all allowed extensions - what sort of file were you trying to attach?

Doug

Com-ple-te-ly off topic:

A team of US specialists discovered today a new crater located in the Nuremberg plains.

The extension of the document is of power point (pps). However, I will copy the image and past into a new document with Jpg or png extension. No problems.

Rodolfo

I have recreated a new document (the original is at home) which is a copy of Teshneiner route map.

Click to view attachment

Angle A1 : Angle in degree from SOL 848 to Near rim
Angle A2 : Angle in degree from SOL 848 to Far rim
Angle B1 : Angle in degree from SOL 855 to Near rim
Angle B2 : Angle in degree from SOL 855 to Far rim
Angle C1 : Angle in degree from SOL 848 to Sol 855
Angle D1 : Angle in degree from SOL 848 to Near rim
Angle D2 : Angle in degree from SOL 848 to Far rim

Sol 848

Near rim
Angle A1=62.0 degree
Distance=539.25 pixels; 952 meters

Far rim
Angle A2=55.9 degree
Distance=888.65 pixels; 1569 meters

Sol 855

Near rim
Angle B1=-59.5 degree
Distance=451.40 pixels; 797 meters

Far rim
Angle B2=-54.0 degree
Distance=803.3 pixels; 1418 meters

Heading toward BC
From Sol 855 to BC :
Angle C1=-72.1 degree
Distance=266.91 pixels; 471 meters

From BC to
Near rim
Angle D1=-51.7 degree
Distance=277.68 pixels; 490 meters

Far rim
Angle D2=-49.1 degree
Distance=636.59 pixels; 1124 meters

Conclusions:
At Sol 848, there is 6.1 degree difference between Near and Far rim
At Sol 855, there is 5.5 degree difference between Near and Far rim
At BC, there is 1.8 degree diference between Near and Far rim.


Every sol, the diference angle of beacon betwee near and far rim will be narrower. Hence, it will be more difficult to identify its location.


The results does not coincides with ones of Horton, due to the lack of precision of positions of Sol 848 and 855.

Word of caution. The measurements and locations of Sol 848 and 855 aren't guaranted to be precise but this give some idea of how the view will happen in the next soles.

I don't claim that my measurements are right. I recognize that I need a more powerfull and image skills tools to measure more precise. That is just for a fun time.

Rodolfo

how come the blue and brown lines cross each other twice??

Blue lines (near and far rim) corresponds to Sol 848.
Brown lines (near and far rim) corresponds to SOL 855.

Yes these lines will cross if one of them is of near or of far rim.

Rodolfo

OK, a few points...

First, the beacon feature is not a point -- it is a structure which changes appearance with changing geometry and light. I am sorry if I have misled anyone. When I use the expression "Victoria Beacon" I mean the extended feature -- not the brightest point for any given time or geometry. I think the shifting position of the brightest point has led to the confusion about its location.

Second, as Oppy gets closer to Vicky, the angular width of any feature on the line of travel will increase -- faster for those on the "near" rim than the far rim.

For example, imagine Oppy 100 meters from a 10 meter block on the near rim. The angular width of the block is 5.72 degrees. The same block on the far rim 800 meters away is only 0.72 degrees wide. So at some distance the position of the beacon will no longer be Victoria's secret. Everyone will say, "aha", chuckle a bit -- and think about something else.

[quote name='ustrax' date='Jun 22 2006, 06:20 PM' post='59462']
Com-ple-te-ly off topic:
A team of US specialists discovered today a new crater

I'm sure we'd see the words "Far RIM" at the base of the Beacon if MRO picts were already available

My point was that two straight lines can't cross twice there's a big bend in the crater itself. why is that?

Cliiiimberrrr!!! You're doing it again! You're deleting either the start quote or stop quote instructions, so you don't get a quote window, and your REPLY button doesn't work! Look, this is easier than climbing Mont Blanc! Get with the program!

OK, where was I...


I wouldn't be surprised if this were true, Climb, but that's because the main road to Victoria Crater comes up from the South . Get it? That's why I turned the MOC image of Beagle upside down. It's all relative! Sheesh.

Edit : not quite eh ?

It's the gravitational lensing effect of the near rim. We've all been deceived...

Forget it, Climb. You can light a BBQ; that's what's important.

[quote name='Shaka' date='Jun 22 2006, 11:21 PM' post='59504']
Forget it, Climb. You can light a BBQ; that's what's important.
[/quote]
Good one Shaka.
Trouble is that I don't know when I started to be wrong! Allow me another try Shaka : when I hit "reply", I have to write AFTER the "[/quote]" that appears at the end and when I want to reply to a part of the message I've got to be cautious not to discard any of the "[]" "[]".

(It'll be amazing if this post works.) That's essentially the story, mon ami. Also, always start your reply on a new line below the slash-quote. When you hit Preview Post or Add Reply, if you don't see a window around the quote, you've screwed the pooch again. Ultreya!

Boys, boys. Settle down. How about we try it with a screen capture:

Ah, a breath of fresh air! You must be another teacher, Dan'l. One picture is worth a thousand words, or in this case, 6378.

Thanks Dan & Shaka...and others, I've got it right this time! I was in a kind of "If something could go wrong...etc, etc"

Edit : back to discussions now

For your next assignment, take a long posting from someone and break it up into quote sections, with your own replies interspersed. This is easily done by inserting quotes and /quotes at appropriate places. Keep in mind, no matter how good it looks, if we can't reply to it, you still get an F.

Brian

For extra credit, light the barbecue. Tell Shaka when it's good and hot. He will be inside marinating near-rim crow which will be served on sol 902.

My good (farimer) friend (note I can reply OK...and U2) we have an expession in french that says "bâiller aux corneilles" (corneilles = crows) which means been there thinking at something else which apply perfectly to our dear Shaka

Now I see what you were referring. That line is a fixing since my tool did not permit to trace a long line between points.

Rodolfo

Oh! - Didn't know the Nuremberg stadium was right next to Albert Speers old grand stand for the Nuremberg rallies.

JPL have joined the Near Rim team

Well let's see what the Captain of the Near Sider team thinks of the JPL rocket scientists' opinions:


Sorry, dude. I couldn't resist

HeeHee...High Fives, all you Knights!

Click to view attachment