Let's separate those two keywords because they actually behave differently.
IMO, a change in site id is decided *before* the move itself; it's a sort of planning decision like "drive from A to B in driving mode X" and then "reset to a new site id".
Changes in drive id are (imo) determined automatically by the rover (call those changes "steps") but I don't see those steps related to distance.



The "steps" are almost certainly related to commanded drive and not actual drive, but not necessarly to distance. Instead of using the current situation as an example, we could go back to Purgatory I. On that time, what happened (have a look to the daily change in drive ids *and* the MER status reports) was that sometimes a step was equivalent to 0.2m, some other ones to 2.0m, and iirc they also had 12m steps executed.
And here we are not talking of autonomous driving modes; in those cases who knows (ok, rover drivers will for sure) how to translate "steps" in meters?

Every time the vehicle drives, the drive number increases. It's not related to distance at all.

After a significant drive, a new site number is declared and the drive number resets to zero.

Now - when you're doing mid-drive imaging (like visidom for slip check or documenting egress progress from a dune) - you have to drive...stop...take images...and drive again..and repeat. Each time you do that - you increase the drive number...

Thus yesterday's driving...
http://qt.exploratorium.edu/mars/opportuni...GBP1230L0M1.JPG
http://qt.exploratorium.edu/mars/opportuni...GCP1244L0M1.JPG
http://qt.exploratorium.edu/mars/opportuni...GDP1244L0M1.JPG
http://qt.exploratorium.edu/mars/opportuni...GEP1244L0M1.JPG
http://qt.exploratorium.edu/mars/opportuni...GFP1244L0M1.JPG
http://qt.exploratorium.edu/mars/opportuni...GGP1214L0M1.JPG

or, more briefly...
1F202400423EFF71GBP1230L0M1.JPG
1F202402217ESF71GCP1244L0M1.JPG
1F202402594ESF71GDP1244L0M1.JPG
1F202402957ESF71GEP1244L0M1.JPG
1F202403340ESF71GFP1244L0M1.JPG
1F202404009EFF71GGP1214L0M1.JPG

The day would have gone...

Take images at same place as yesterday Site 71, Drive GB..
Drive a bit, thus completing drive GC
take images
Drive a bit more, thus going to GD
take images
etc etc - up to GG

Tomorrow, we may see a similar increase, starting with GG for start of day image, then subframes of progress with GH, GI, GJ, GK, GL etc...

Doug

Doug, Tesheiner, James,

Thanks for the replies. Makes much more sense now. This pointless exercise is hereby concluded for me too!

Castor

Tom, it is clear that Oppy is headed into an old crater, the depression means a lower wind velocity and net deposition of sand and apparently softer sand.

I'll suspect that Oppy will go a biy westward and step along the outcrop stepping stones instead of staying due south.

--Bill

Referring to this document ("The Mars Exploration Rover Surface Mobility Flight Software: Driving Ambition"), I think a drive number increment is triggered whenever a "Low Level driving primitive" is executed. They may be automatically commanded by the rover (in autonav modes) or directly commanded from the ground. The latter was almost sure yestersol's driving mode.

Edited: Finished from my side too; it's getting too technical to fit in this thread.

Bill:

I'd been wondering about that too - there must be lots of old craters covered in surface drift material, and from a distance such traps would look very much like any other part of the landscape. It seems perfectly reasonable to expect a fluffy and uncompacted texture. We may just have been very lucky so far!

On a statistical note, we've had one bad dune and one halfway bad dune; and we've seen less than a dozen small craters overall. The numbers seem to tie in, don't they?

Bob Shaw

Where would you cross over? Just head west over the dunes maybe a little bit back north, or head all the way back to the exposed rock where they veered off The Thin Blue Line to avoid major ripple crossing?

Brian

Just to clarify slightly - Doug's reply makes it sound like the drive number is incremented by one for each image taken. This is nearly always not true. See my plots in this post points are shown with the difference in drive number between consecutive images. Most site/drive numbers have no images (100's at a time sometimes) - I suspect that the drive number is incremented whenever an internal mesurement is taken (rover orientation, etc) not when a picture is taken at a new position. Note there are some cases where a small movement of the rover happens but there is no increment in drive number.

James

Interesting correlation if true...and an outstanding example of the value of "ground truth" vs. remote sensing! The MERs just keep on giving & giving...

Of course, one could also put visidom slip checks into the catagory og 'internal measurement' - and those images rarely get downlinked

Doug

Example?

Looks like it...
Looking at your anaglyph it seems, to me, that there are some other ancient ones scattered all around:

http://i16.photobucket.com/albums/b14/ustrax3/scr.jpg

ustrax: There surely are many ancient, and sometimes overlapping craters in this region that are now partially mantled by the more recent windblown sediment. Bill took a stab at identifying some of them a while back. Identifying them is really is a bit subjective. The circles I would draw on a map would problably not always agree with those drawn by someone else, but we could all agree on some of them.

The rover-based imagery really helps out in this regard. Erebus really looked like an ancient crater from orbit, and when Opportunity arrived there, "the most casual observer" could see through her eyes that it truly was a crater. This one is slightly less obvious, but Opportunity shows it to us from her perspective.

Here is an anaglyph view from Opportunity on sol 830. Making a good anaglyph of a stitched panorama can sometimes be quite challenging, and this one is less than optimal. It is just a quick and dirty Autostitch of pancam anaglyphs from MMB. I think it turned out better than my other attempts to create a more refined anaglyph. I do not know how it appears to others, but I can see a slight depression ahead, and the far rim as a local high that is obscuring the view beyond.

If Opportunity can make it to the opposite side (and I have little doubt she will make it), we might finally get the "hell of a view" that we have been anticipating for so long. From the other side, I hope we will have a much nicer view of Corner Crater and the Victoria ejecta blanket escarpment that appears to be behind it, not to mention, of Victoria in all her splendor. Well, at least in some of her splendor...

P.S. By the way, did you read the abyss piece from Kazantzakis that I sent to you? What did you think of it?

Is that really true? I thought nearly all these images were downlinked in the end, hence why lots of driving can start to fill up the flash, as these images are not deleted soon after the drive.



Well there are several examples in the tracking database where there appears to be movement e.g.



But after looking at the images

http://marsrovers.jpl.nasa.gov/gallery/all...TTF0006L0M1.JPG
http://marsrovers.jpl.nasa.gov/gallery/all...TTF0006L0M1.JPG

There doesn't appear to be any actual movement - another mystery...

==

btw: Good to see JPL have given up trying to keep up and are using your map now!


James

I think both of you are right.
Those pics are rarely downlinked, yes, but just because of the priority queue.



Mmm, when, where? Are you talking (maybe) about the pic in Planetary Society's MER Rovers Update?

Oops, yes, I wasn't quite with it yesterday.

See my comments on this other thread. I thought it was too technical (but still interesting) to continue it here.

Yes...I agree, even if that can mean non pleasant surprises for Opportunity in situ...

The anaglyph gave that impression too...Hope not but the rover is moving through a 'mine field' with sand as camouflage...
Splendor?...Fasten your seat belts! Near rim is our destiny!

And yes, I've read on those glorious Ultreya / El Dorado days the Kazantzakis you've sent me...
I can tell you some of the ideas had become a sort of beacon...It's there...So find the better route.
I'll send you an e-mail with my impressions about it.

And thank you once more.

Edited: "Where is the abyss? That is where I am headed. What is the most valiant joy? To assume complete responsibility!"

Sol 841 drive wasn't really big in terms of distance, but given its significance I think it deserves an updated route map.

Click to view attachment

Yessiree Bob! Go west, young MER!

Yeah, westward is the general direction. If I were driving I'd back up a bit more and then head roughly southwest.

Ustrax: Interestingly, the 4 drive direction pancams from sol 842 are centered on -120 degrees, essentially southwest, possibly looking for a route to the "near rim." From the orbital imagery it appears that there might be a high road around this abyss in that general direction. I agree that the straight across route is a mine field.

It appears to be not a large detour and is probably a safer road to travel. It really does seem to be our destiny.

With apologies to others for this embedded personal message to our intrepid explorer about philosophy (feel free to ignore), I feel I must say that the abyss is at once our obstacle and our motivation. I often find myself wavering between these thoughts quoted from the writings of Kazantzakis.

8. But I, the Mind, continue to ascend patiently, manfully, sober in the vertigo. That I may not stumble and fall, I erect landmarks over this vertigo; I sling bridges, open roads, and build over the abyss.
20. In sudden dreadful moments a thought flashes through me: This is all a cruel and futile game, without beginning, without end, without meaning. But again I yoke myself swiftly the wheels of necessity, and all the universe begins to revolve around me once more.

I don't know about the rest of you, but I suddenly feel bettter...

And so you should, Tom, for we here follow a path that no foot has trod before.
"...without beginning, without end..." Yes, assuredly, but "without meaning"? If "meaning" has meaning, then we stand at its apex!

This is surely profound, for we go where the hand of man has never set foot.....
Kenny

Dredging through the haze of decades, isn't that sort of line used in the Tintin book The Calculus Affair (L'Affaire Tournesol)? Tintin, following his earlier adventures of Explorers on the Moon, is met by a man keen to shake the hand which first set foot...

Andy

Through my own haze of decades, je ne sais pas.....

But how appropriate is your recollection, for isn't our Oppy just a little "tournesol" itself, twisting this way and that to catch a few warming rays....

Kenny

Route map, updated to sol 843.

Click to view attachment

Excellent! I just saw the 843 images and Tesheiner's map. I was expecting at least a short investigation before leaving, but apparently Opportunity is already heading back toward the blue line. The edge of the old crater is likely to be not only safer, but also more geologically interesting.

And what if the abyss should guard with his dark veil marvels way beyond the bridges, roads and landmarks? What if the Mind, ascending (what already whispers that from the deep has come), is, simply returning?

It looks like the "short investigation" was limited to "take pancam pictures of it in all filters and put them on the downlink queue but not with highest priority".

Aren't we just a bit over halfway between Erebus and Victoria?

No, we are nearer (can we say "nearer" or "more near"?) to Victoria than Erebus. There is a few decameter to Victoria (around 800m ~).

Only because you ask, Ant, we can say:
1. Yes, we are nearer to Victoria than to Erebus. (And it will be true.)
2. Yes, we are more near to Victoria than to Erebus. (And it will be true, though uncommon speech.)
3. Yes, we are nearer to Victoria than Erebus is. (And it will be true, though irrelevant to the question.)
We cannot say:
4. No, we are nearer to Victoria than to Erebus. (Because it both negates and confirms the question.)
5. No, we are nearer to Victoria than Erebus. (Because of reason 4. and because it is equivocal.)


....13,834 bottles of beer on the wall...

Thank you M. Shaka to confuse even more my French friend
He asked for 2 possibilities and he's got 5 answers including 2 wrong
Ant 103 : la prochaine fois, il faudra le dire en Français

And in fact while Opportunity is closer to Victoria's rim than to Erebus' rim, she is still fractionally closer to Erebus' centre than to Victoria's.

Click to view attachment

Or, as we say in Glaswegian French: 'Je ne dinne ken pas!'

Bob Shaw

Oh my, you're getting me so nostalgic. I used to live in Jordanhill (Glasgow) from 1970-84 (a Sassenach from Yorkshire). I no longer have the accent (living in England and Texas will do that to you) but it's fun to hear it again from time-to-time

Yes, I've been waiting for those also. It is not as if they have so many images being sent down that some should have to wait so long.

We've reached 100 pages on the topic!

Okay.

Non, nous sommes plus près de Victoria que d'Erebus. Comme ça au moins, je me trompe pas

Scuse me for no french speaker...

38 for me, it depends how you set your preferences. I think numbers of comments is a better measure as it is independent of personal board settings

Now only 9 to the 1500th

Reply number 1492, the date of the discover of the America by Christophe Colomb.

What a sad day ....

Updated route map (sol 844).

Click to view attachment

That's much better, Ant, but to be perfectly correct you should say:
Oui, nous sommes plus près de Victoria que d'Erebus.

Because what gregp1962 said: Aren't we just a bit over halfway between Erebus and Victoria?
means the same.

[quote name='Shaka' date='Jun 9 2006, 10:52 PM' post='57825']
That's much better, Ant, but to be perfectly correct you should say:
Oui, nous sommes plus près de Victoria que d'Erebus.

Oh oh, I see that I'd better watch my friend too, M.Shaka is very correct

Updated route map (sol 846).

Click to view attachment

I have the impression that at about 100m south of the current position the terrain may be a bit smoother, at least there seems to be a change on its roughness (?) by looking at the route map.

Oppy has took another mini-valley of crest after crossing two crests of ripples. Its new channel of valley, will go southward where will meet somewhat buried outcrop. After the outcrop, I seems the track will have more sand deposition. Let see how is the next days. However, the new minivalley, in general view, seems it is going for a long way as Tesheiner has calculated as 100 meters.

Rodolfo

Yes, that channel / trough goes a long way.

..and what about this dark, stright highway?
Click to view attachment
someone is indicating us a path, but do not seems really safe to me...