This event deserves its own thread.

To quote the illustrious Dr. King -- "Free at last, free at last, thank God Almighty, we're free at last!

So, how much y'all want to bet we'll stay here for a few sols, looking very carefully at the tracks and waiting for the MER Team to figure out how to proceed from here?

-the other Doug

Surely does deserve a new thread. Otherwise people looking at the front page are just going to see the old "Stuck" thread and might miss the news.

People in the other thread weren't very happy with the suggestions to go examine the trench, but in my opinion they have to do that. There should be no fear in doing 180 degrees now and sticking the IDD in the trench for a few sols.

Actaully I am amazed they never took the IDD out during the time Oppy was stuck in the dune.

WIIGII!!!!!!!!!!
Good Job Mike and the whole Rover Team!!!!
/rick

I (for one) absolutely agree they must go back and bring all the instrumentation to bear on the trenches to make sure they understand exactly why it embedded itself.

As far as taking the IDD out while still in the trench I think they were worried about power and driving (or churning) was the priority. They had to go back to deep sleep mode over the past few days because the increasing tau is dropping the amount of power being generated.

Yes, free at last! Great - and now to move on...

This is the polar projection of the pan I posted before:

http://www.unmannedspaceflight.com/index.p...findpost&p=9494

(I hope this attempt to link back to an earlier post works... I didn't want to repost the image)

Presumably some time will be spent here looking at the trench and planning the next move... though I really don't know what diagnostic information on drivability is likely to be forthcoming from looking at this quite commonplace drift.

The image suggests to me that the departure might be planned by keeping down in the valleys between these large drifts. But you could only plan that about 10 or 15 m in advance. So Opportunity could drive a sinuous route ahead, day by day, until it gets on to firmer ground (which I think is not far ahead on a patch of darker plains). Now I am *really* looking forward to seeing Erebus.

Phil

As I've just been out for a pizza and missed all the action, all I've got to say is squeeee!
Reckless

I guess too they will still spent (much) time here. It could be very interesting to investigate around here why or where all-around there is such another ground composite. I guess they aren't so frustrated as we are and dont have the same (big) appetite to go away from here (sadly )

Check out Steve's second June 4th update. He discusses the possibility of investigating the trap, and where they'll go next.

http://athena1.cornell.edu/news/mubss/

About investigating the traps, "we'll only do it if we're convinced it's safe".
The still going to south but, for the moment, no words about new course strategy in order to avoid other stalls...

That's one heck of a deep trench. (With Opie's luck it will be filling up with water soon.)

From MSNBC:
Where will Opportunity go?
Eventually, Opportunity will resume its southward trek, heading first for a bright feature nicknamed the Erebus Highway, about 130 yards (120 meters) away, Squyres said. The "highway" could be a stretch of exposed bedrock, leading toward Erebus Crater — which would be a very good thing for Squyres and his colleagues. Or it could be a huge pile of Martian dust.

"If it's dust, then we've got to stop and rethink a whole bunch of things," Squyres said.

Squyres said the mission team intended to have Opportunity press on to Erebus Crater, roughly 440 yards (400 meters) away, despite the past month's difficulties. "To just turn tail and run after we've had one unfortunate event is just not the way we're going to do business," he said.

But he said Opportunity would go at a slower pace from here on out, taking more advantage of the safety measures built into its software.

"The first rule in a situation like this is, do no harm," Squyres said. "These are literally priceless machines. ... We're going to move thoughtfully on this from now on."

Well, this is my first post. Let me start by thanking Doug for the great forum and everybody for the great pictures.

The extraction process raised one question. I previous posts in this forum it was mentioned that the rovers did not have a direct method of determining if the wheels were slipping. However, from the pictures it looks like after Opportunity came free it only drove about 0.5 meters. As JPL has been talking about 20 meter drives, did they get lucky and get out after driving 19.5 meters (a 1 in 40 chance), or could they detect that the slippage had stopped?

If they can detect slippage, this will make further driving much easier.

Rob

OMG, a modified First Law of Robotics...

--Bill

They could have also included a bogey angle as a trigger to stop the drive. When the wheels leveled out, that was almost a sure sign that the wheels were on firm ground.

Or motor current - I'm sure that a wheel on the surface will draw fewer amps than one in a trench

Doug

I think we can all associate with that statement!

What a relef.

James

I am really happy to see Oppy free at last!!!

It is wonderfull to think that such a dramatic situation was repaired only from remote control, at millions of kms... Already Spirit was mended from a software problem some days after arrival. Fantastic!

It is even better than is science fiction. In scifi, there is a super-heroe who uses his superpower to fix problems in some seconds. In reality it is hard work of teams of hundred of ordinary people who do the job, with long hours of work, thorough thinking, long tests, complex calculations. Whoooo!


Spirit and Opportunity are not just machines or money, they are our eyes and nose and fingers (robotic arm and instruments) on a distant world, something that I could even not imagine when I was a child (not so long ago, we knew of mars only a red ball with Shiaparelli's channels). So losing them would be really a love drama and philosophical loss.


More pragmatically, missions in space are so long and so costy, than it is far better to spend money and time for ongoing missions rather than to launch new ones at the cost of ongoing ones. Think to the Voyage probes, now entering the heliopause and in the interstellar space in some years: would we launch a mission to this place, it would not be there before 30 years.

I fully agree with this quote of Steve Squires. Of course, they will be cautious, they will first examine the trap, understand how it happened. Then they will start to move again, slowly and cautiously, but they will go.


This page of Mars Geology's site shows (among other things) a large image of the further path to Victoria (Larger image, 2Mb download).

The etched terrain looks very tricky, with larger dunes, rocks, rock pits, perhaps the rock-only version of Anatolia. Especially Erebus looks like a profound sand trap. It will be difficult and slow, but here are intersting things.

Hi all,

I was planning to periodically update this panorama (here), but the final movement was so "big" (at least based on last week's drives) that I couldn't stitch sol 484's pancam image to the previous ones.

So I made a new one, from pancam images taken on sol 447, overlayed with the overall progress since sol 461 until 484.



Tesheiner

Wow, I go away for a weekend and look what I missed! Add my belated congrats and Mars Bars to Oppy's team for a job well done.

Since nearly everthing significant the rovers encounter gets a name, is there an "official" name for the offending dune? I'll bet the MER team have several non-family friendly ones the've used

Last image of the left rear wheel before becoming unstuck

I wonder what caused the parallel grooves in the soil stuck to the wheel.

Maybe the other five wheels were supporting the rover, and this one was just spinning, brushing against the soil surface.

"The Great Escape" the movie

http://www.upitfree.dk/upload/files/front_left.wmv

http://www.upitfree.dk/upload/files/front_right.wmv

Fantastic, dot.dk! The movies really give an idea of the struggle and timescale. Too bad there's no audio, I'd love to hear the sound of the wheels catching firm ground at the end

Excellent movies dot.dk and no Jar Jar Binks. bonus

Reckless

http://www.msnbc.msn.com/id/8119808/

NASA plots Mars rover’s next moves
After freeing Opportunity, team plans for safer driving

Team members gathered at a Sunday barbecue to celebrate the breakthrough, and were back in their offices on Monday to plot out the next moves.

Boy, they deserve it

I'm no geologist but as I look at this shot of Erebus:

http://www.marsgeo.com/Photos/Opportunity/Etched.jpg

It looks like there is a circumferential ring around the obvious center of the crater and that this ring crosses Opie's course right about where she got stuck! Could this be the origional outer edge of the crater which is much larger than supposed and has now been filled with dust? If one uses a lot of imagination one can see parts of a corresponding arc continuing around the southern side of the center. Could it be that Opie started to approach the original rim of the Erebus crater? I have a real bad feeling about going any closer to Erebus center from the north. Better to go around it and approach from the south if it looks more solid in the etched area?

This "bad feeling" hit me too, when answering to and interesting question from Vladimorka in the other active thread (http://www.unmannedspaceflight.com/index.php?showtopic=947&view=findpost&p=11968)...
My fear is that, based on bottom of rover tracks profile, Opportunity is entering in a completely new terrain, were hard soil became deeper and is covered by thicker sand layer... extention of this new terrain is clearly visible in this elaborated version of your image (I highlighted upper border):

In the "route map" thread, someone theorized that this terrain (called "Terra Nova") could be an ancient, buried crater, eventually overlapping Erebus north Rim.
If this is true, they should avoid moving directly to South direction and try to circumnavigate the hidden crated going to east!

odave:
I'd really love to know that name, too.


dot.dk: Nice work, as usual. Those are two animations I really wanted to see. Thanks. I'm on the road and was really hoping someone would do them.

Parallel grooves on the wheel may be caused by a chunk of stone or something buried. It may be related to the fact that Oppy regained traction, if Trader is right.

Hi Trader and Dilo,

I am afraid you may be right. This suposed buried crater at north of Erebus is not obvious, but now that you showed it, it is visible.

Note that there is also one buried crater east of Erebus. Oppy should avoid both.

If so, you are right, Oppy should go east immediately and only after resume its road south to the etched terrain.

This etched terrain could be only the same layer of rock than in Endurance, just more exposed. But it could also be different, as the abundance of large craters indicates it is more ancient.

Anyway there seem to be, in etched terrain, larger dunes, rocks and pits, which make it very dangerous.

and so it begins...................

scott

I believe I disagree entirely. We have ground truth as to what the current terrain is like -- that scalloped, fish-scale pattern of light markings are high drifts of very soft material. The first time Oppy tried to drive through the center of the lightest portion of one of those scalloped features, it got stuck in very soft powder.

To the east (right), there is nothing but more of this fish-scale patterning. We know that this is going to be more of the rover-trap soft-powder dunes.

The darker area, on the other hand, looks like it's back to the blueberry pavement with low (10cm or less) drifts. It looks like far safer and faster driving than going to the east.

In fact, I'd head southwest to get to this darker unit as fast as possible, and then straighten out to the south and head for the rim of Erebus. Now, getting from Erebus to Victoria could be dicey, since there are a lot of obvious tall drifts and serious dunes crossing the rim and extending to the east -- just the direction you want to go to reach Victoria...

-the other Doug

Hello dvandorn,

who is right, you or Trader and Dilo?

I have some arguments that white "fish scales" are rocks, as there are some dunes showing in dark over this clear background.

But absolutelly we shall be sure only when there will be a camera on it.

First, they will try to find if the sand Oppy was trapped is different of other sand. Until now we even not know why Oppy dug in this peculiar point. Was the cause internal to Oppy (software bug, safety disabled?) or in the terrain (finer sand, more deep?). If they find that the sand is safe, they will continue that route; if they find it is worse, they will find another one. Perhaps hey will try to run for one metre or so, just to test the sand.

We shall know in some days.

Hi dvandorn,

Appreciate your comments -- have been following your informative inputs for some time.

What is bothering me looking at the terain is the large ridge running east to west across the predominently north-south wind drifts -- what's under there causing this ridge? Why is this orientation so close to an arc segment around the visable center of Erebus -- old rim or shock line? Is this a filled-in, crusted-over Anatolia-like region? If I look at the trenches from Opie's misadventures, they seem to be only partially filled suggesting possible voids, or at least lower density material, under the surface crust. The dug-up powder incidentally reminds me of a ladies cosmetic face powder in both texture and color!

What caused the crusting -- rain or frost on the surface "powder and sand"? Does the surface color (composition) tell us anything about the underlayment for the crust or is it much newer material blown and sorted over the crust? I suspect a lot of "jumbled rock piles" under there with unpredictable voids under the crust. Scares me and I'm fearless!!!

All of this is my best guess -- after all, I'm not an Areologist. But it seems to me that the east-west trending "ridge" is indeed the remnants of the northern rim of an ancient impact crater that has been filled in, its rim almost entirely obscured. The question is not so much whether the "dark patch" north of Erebus is an ancient crater (which I t hink it almost definitely is), the question is how and when was it filled.

If it was just filled by windblown dust, it could be a huge pit of soft powder that will act as a rover trap. But I don't think that's how it got filled.

I think this crater was made *before* Mars dried out and froze up, and that the ancient sea filled it. That would mean it's filled with sediments from the ancient sea, which means that it's filled with more evaporite and sandstone. Which ought to provide good, solid footing under the drifts.

I also don't think there is anything like duricrust on the drift surface that was "broken through" when Oppy got stuck. I think that Oppy got stuck because the drifts are more and more powdery in the white-ish fish-scale drift arcs and it managed to get itself in a position where it had three wheels on one side of the drift crest and three wheels on the other side, causing each side to try and slide in opposite ways. Since the rover can't slide to both sides at once, instead, it dug into the powder rather than riding on top of it. Yes, there is some kind of cementation process that occurs to the soils over a lot of Mars' surface, and yes, there are layers in these drifts that demonstrate varying compositions of the dust that makes them up. But these drifts formed a *long* time after there was rain on Mars, I think -- I don't think that groundwater or precipitation has caused the drift surfaces to become cemented.

In the long run, what I *don't* want to see is the MER Team lose its courage and fret about rover traps over every hill and beneath every drift. The whole purpose of the MERs is to see what's over the next ridge, and as long as we have a fair degree of confidence that we can dig out of soft sands when necessary, I say we should try and visit as many of the landforms here as we can. The darker "fill" inside the ancient crater north of Erebus looks like a slightly different landform, and without any ground-truth that arguies for that fill being unsafe, I'd say go for it...

-the other Doug

Trader,

I also noticed that the volume of disturbed soil seems lesser that before it was disturbed. How to explain this?


This would imply for instance that the dunes were formed in an unique episode, with more air and snow powder. After, the snow evaporated, lefting a low density material which remained in place, forming like a bread with a crust and hollowed inside.

But of course this is very prospective.

I noted on photos of Mars that often the surface facies changes drastically in some hundred of metres, without apparent reason. And as a matter of fact, it changed, from the hard flat layers with very small dunes around Endurance, to larger dunes with less or no hard layer under.

Compaction of soft, fluffy powder. Not hard to explain at all. And the material lower in the drift kicks out quite nicely, so it's already more compacted.

There is similar dust and sand drifting all over the planet. I seriously doubt it was all created in one big global snowstorm three billion years ago, back when snow was possible on Mars. You have to remember, it has been eons since Mars' atmosphere was thick enough to support precipitation like that. These are classic windblown drifts -- there's no reason to postulate precipitation when none has occurred for at *least* millions of years. Besides, we've seen minor changes in the drifts (outside of Endurance) in the time Oppy has been at Meridiani. No, these drifts are still in the process of creation/deflation, and I feel pretty confident in saying they're all simple aeolian features.

First, I bet there's a hard blueberry-paved surface under these drifts. Second, the facies don't change without reason -- we just don't see the reasons at first glance. In this case, the difference is probably as simple as wind erosion shifting from eroding the blueberry paving to eroding a greater percentage of evaporite outcrop, resulting in different grain size and mass. Which creates drifts of different composition and structure. Add to that the windbreaks caused by the low rims of Erebus and its fellow ancient craters (making up the ancient crater cluster that lies to the west of Victoria), and voila! you have all the reasons needed for the change in the facies.

-the other Doug

Doug, I sincerly hope you are right!
If, after one or two meters movement in south direction, slippage will appear low, MER team should go back to original mission philosphy ("try and visit as many of the landforms here as we can")...

Hi Richard, Dilo and dvandorn,

First, thanks Richard for the reference (link) that showed the macro picture in the vacinity of Erebus. I had seen this earlier but forgotten about it and had never looked for the detailed features around where Opie got stuck.

dvandorn, you are probably correct about all or most of this -- I sure hope so as your view paints a more optimistic picture than mine. However, I still beleive that we are moving around over a crusted surface with unknown (variable) underlayment and that the observable (small scale) surface covering likely does not correspond to this underlayment configuration or composition. This hypothetical crust is likely varying in thickness but appears to me to be 1 or 2 inches thick and chalky (fair compression and very little tensile strength -- some visable fracture patterns but mostly crumbling features) along the sides of the trenches in the area where we broke through. I would still bet on water genesis even without knowing the area composition and chemistry. As for rain, that was suggested largely in jest; but, frost was not -- we had visable frost on the surface just this past season which, as I remember, some in NASA postulated may have played a role (dust clumping) in the cleaning of Opie's solar panels. This much atmospheric water on the surface today -- how much over even the last thousands and millions (not billions) of years? Perhaps enough to incrementally penetrate the dry powdery soil 1-2 inches and weakly cement the surface with disolved and recrystallized salts? Just an ole country boy's analysis and half baked speculation.

The fluffy-dust surface material the snared Oppy is indeed unusual. Light and porous, yet cohesive enough to stick to the wheel's treads and then break off leaving tread flakes. And recall how much the disturbed material darkened in just a few days, suggesting that it is reactive.

Interesting stuff and worth a second look, even if to characterize it so that it can be avoided.

--Bill

Totally agreed. If you'll recall, back when I picked Sol 479 for Oppy's un-stuck date (OK, so I was five days' worth of optimistic), I also predicted we'd spend several days investigating the dune in which we got stuck before we'd move on towards Erebus.

OK, so I forgot to add the three days of celebration the MER Team would (deservedly) partake in before they got back to working...

-the other Doug

Dvandorn,

thanks for the discution about the possibility of snow precipitation.

When I evocated such an hypothesis, I was not thinking to a wet Mars three billions years ago (the dunes cannot be that old) but to more recent episodes.

What I think is that occasionally there are on Mars volcanic episodes (or mud flows like in Cerberus) which release large amounts of steam or water. Part of it would produce a temporary atmosphere, with wind and snow, perhaps rain in some places. Such temporary wet episodes would explain many things which are otherwise mysterious.

In such a case, a temporary atmosphere would produce a kind of blizzard for some days, until all the water vapour condensates in a way or in another, mainly in the polar caps. In this case the dunes would undergo more changes in some days than in a million years. And a dune composed of 80% basalt dust and 20% snow dust would dry lefting 20% void.


But there are also more classical explanations to the behaviour of the dunes.

Any idea where Oppy was on this image when it got stuck??

Scott

Here: http://www.unmannedspaceflight.com/index.p...ype=post&id=635

That's great. Thanks.

My suspicion is that the lighter colored dunes are windblown fine dust eroded from the brighter areas of "etched" rock. If you hit the light colored areas in a dune field, watch out. But the brighter colored "etched" areas are likely to be more rocky (they define rims of craters and do not appear to have dune-like striations). Interdune areas are scoured out (relatively) and should consist of a harder surface. Lee sides of dunes should be softer than windward (they are composed of "fall" dust; windward sides are composed of driven dust). Lee sides should also be somewhat steeper than windward.

What I really wonder about are the slopes of Victoria. They are dark and duneless and are elevated above the surrounding plain. I would assume that they are hard-pan pavement with most dust blown away.

The dunes between where we are now and Victoria, based on their shadows, could be 4 times the size of the ones we are in. They are likely large rolling dunes with smaller dune crests and structures on them that cannot be seen in the orbital images.

Scott

This is probably OT but it didn't seem worthwhile creating a separate thread...

Re images on the exploratorium site for 8 June, why would they have got Opportunity to take a very large number of navcam pics of the same patch of the rover tracks?

Also surely that boulder among the 8 June panscan downloads cannot be at Opportunity's present site. It looks more like one from way back in Eudurance crater.

TOTALLY un-needed quote removed - there is no need to quote an entire post when you reply to it. - Doug

Yes, it was taken last October,07 (based on image name) and is a detail of a big rock called "Wopmay" inside Endurance crater.
This isn't the first time that some old images appear in the Exploratorium; some days ago, they posted also images from very first Sols immediately after landing ( ) and I cannot believe they remained inside Rover memory so long...

Sorry for being OT (Besides this thread already is OT):

This stupid quoting starts to bore me.