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Posted by: alan Jun 18 2007, 06:44 AM

I've been keeping an eye on the sundial images looking for signs of a cleaning event. I've noticed some changes in the latest to be downloaded although they may be due to changes in the lighting.

A : clean patch at top of circle streak at bottom
B : increased contrast from dust left behind next to mirror
C : clean patch next to wire

Also note the missing clumps of dust on the deck


A broader view show a contrast between sol 1221 and 1227
http://207.7.139.5/mars/spirit/navcam/2007-06-10/2N234768899EFFATI4P0165L0M1.JPG
http://207.7.139.5/mars/spirit/navcam/2007-06-16/2N235294462EFFAU00P1914L0M1.JPG

Has anyone heard if there has been a change in the power levels?

Posted by: akuo Jun 18 2007, 09:06 AM

The lighting would appear to be almost exactly the same, as the shadow positions are almost exact.

I think you are correct about the changes you point out. I imagine the overall cleaning effect would be small, though.

Posted by: jmjawors Jun 18 2007, 11:42 AM

Just saw the latest images and rushed here to find out what more knowledgeable people were saying about it. But my impression was also that she's had a cleaning event.

Posted by: centsworth_II Jun 18 2007, 03:33 PM

The definitive answer would come in the form of a boost in power.... waiting... hoping...

Posted by: fredk Jun 19 2007, 03:50 AM

Yes! We're above 600 Whr!!

http://marsrovers.jpl.nasa.gov/mission/status_spiritAll.html#sol1219

Posted by: dvandorn Jun 19 2007, 04:11 AM

When you look at the rocks in specific and the surface in general, it sort of makes sense that an object like a MER would get wind-cleaned several times over the course of a Martian year.

If there was nothing happening on this surface except steady dust accumulation, the local surface would be buried in millions of years' worth of dustfall. The winds have to be capable of moving the dust along, or else the rocks would have dust caps and be buried in airfall dust. The fact that the rocks are not generally dust-covered (and are in fact aeolian-sculpted) and the soil is not completely covered with airfall dust argues for enough wind to blow the dust off the rocks at a greater rate than the dust falls out of the air.

Of course, no one could have known if the periodicity of deposition/deflation events would be timed well enough to keep a solar powered rover working over a long haul. And extreme dustfall events, like global dust storms, would still probably doom a MER. But, on average, what we observe on the scene suggests an environment where solar panels will be cleaned just slightly more than they will be dirtied.

If you want more proof of this general charateristic of Mars, look at the HiRISE images of the Vikings. They retain some of their blue-white coloration to this day, which means they have been cleaned more than they have been dirtied. It's only a gross confirmation, but it suggests that objects on Mars won't become (or remain) completely dust-covered on the scale of decades to centuries.

-the other Doug

Posted by: mhoward Jun 19 2007, 04:12 AM

The news we've all been waiting for!

Posted by: dvandorn Jun 19 2007, 04:13 AM

Oh, yes, and I forgot to add: Above 600 Whr!!!! Hallelujah!!!!!!

-the other Doug

Posted by: slinted Jun 19 2007, 04:33 AM

This is great news! That great a percentage increase is impressive, considering just how dusty Spirit was.

Here's a pancam comparison between sol 1213 and 1223, showing one spot (also visible in alan's images above) partially cleaned by the wind:
http://www.lyle.org/~markoff/collections/2P234046358EDNATETP2104L2M1_2P234934570EDNATI4P2104L2M1.gif

Posted by: CosmicRocker Jun 19 2007, 04:33 AM

Alan: You're the man with the first good news in a long time. Congratulations.

I recently noticed some DDs apparently moving toward Spirit, which seems to be an unusual direction for them.

Very good points, O'Doug.

Posted by: Jeff7 Jun 19 2007, 05:03 AM

Most excellent news.

Posted by: ElkGroveDan Jun 19 2007, 06:04 AM

OK where's Helvick? We want to see that chart now!

Posted by: djellison Jun 19 2007, 08:08 AM

Looks like a self portrait was put in work yesterday after the cleaning. I'm REALLY out of stitching practice

Posted by: akuo Jun 19 2007, 08:22 AM

The solar cells looks patchy, like the wind cleaned some parts and left clumps of dust behind. This is in contrast to the overall hazy appearance of Spirit's deck previously.

Great news about the power levels!

Posted by: helvick Jun 19 2007, 08:41 AM

We're well past the edge of my charts now and my extrapolations would appear to have been too conservative. I had thought she was at slightly below 400whr prior to this cleaning event but it appears that she was actually about 100whr higher. This is probably due to errors in the insolation\atmosphere model that I used (which is based on pre pathfinder data IIRC) and an over aggressive estimation of dust deposition.

I'll rebuild the chart and try to adjust for the errors to see what that produces. It will take a day or two though to dust them off, so to speak.

Great news though - this gives her another respectable extension on her life expectancy.

Posted by: centsworth_II Jun 20 2007, 02:43 PM

Well, it's got to be asked : Was it a DD or a wind gust that cleaned Spirit?
Do we know if this one happened at night, or during the day?

Posted by: elakdawalla Jun 20 2007, 03:04 PM

I was actually wondering about that. How finely can they pinpoint when the cleaning event happened? With what time frequency are the solar panel outputs measured during the day? Obviously it isn't measured at night, so if it happened at night, I'm guessing all they can say is that it happened at night. When were the pancam images taken that bracket the event?

--Emily

Posted by: alan Jun 20 2007, 07:16 PM

This is the best I could get out of Autostitch

Posted by: dvandorn Jun 20 2007, 08:00 PM

Yeah -- you can see she's cleaner than she was, but it wasn't a full cleaning event. The panels near the ends of the wings are still pretty dirty.

Still, any cleaning whatsoever at this point is a gift, and I accept it gladly...

-the other Doug

Posted by: ElkGroveDan Jun 20 2007, 10:54 PM

As I recall these events aren't isolated ones. I bet we'll hear about another one in a few weeks bringing it up to 825 whrs. Didn't we reach a point the last time where they were keeping her up all night to shed excess heat from the return to 900 whr?

Posted by: Tom Tamlyn Jun 20 2007, 11:45 PM

I hope your prediction is correct, but wasn't Spirit at a higher, more windy elevation when the previous series of cleaning events took place?

TTT

Posted by: climber Jun 20 2007, 11:52 PM

Yep, she was right in a pass when she get the "big" cleaning event which, to me, think logical. By any mean, yes, she was much higher.

Posted by: edstrick Jun 21 2007, 07:22 AM

"I doubt they get engineering data at a high rate all the time the puter is powered up. Maybe not much or any when it's more or less on standby. Generally, I think events will probably happen between blocks of data.

Anything after sunset and before sunrise can't be detected by solar power changes regardless of whether the rover is taking data or not!

Posted by: helvick Jun 21 2007, 09:11 AM

I've asked about the engineering data before (and I was specifically looking for the periodic Solar Panel output currents) but was told that that's not going to get published. As I understand it engineering data would have to be stringently reviewed to make sure it didn't breach ITAR and that would be too much paperwork for not enough end user benefit and to be fair that was a perfectly reasonable answer.

I haven't been able to find any data on the sampling period for this either so I can't say if it is taken more frequently than once per day. Prior cleaning events have generally been vague about the precise timing - generally indicating that power levels have increased between sols so it is possible that only one sample measurement is recorded per sol.

Posted by: CosmicRocker Jun 22 2007, 05:45 AM

That doesn't make sense to me. I would have thought that engineering data consumes a relatively small amount of bandwidth compared to images and spectrometers. I think I appreciate that there are many sensor feeds, but surely they monitor panel output more often than once/sol! Where am I going wrong?

Posted by: RobertEB Jun 22 2007, 02:00 PM

I was looking at the picture above and I noticed the hinges when a thought hit me. Would closing the solar panels and opening them back up help knock the dust off. Maybe they could even shake them a little.

The only problems I see are, one- dumping the dust elsewhere on the rover. Two- the possibility of not being able to open them again.

Posted by: Tom Tamlyn Jun 22 2007, 02:14 PM

Pete Theisinger was asked about closing the solar panels in an effort to get rid of dust on a webcast that I've seen. (I believe that it was during the Q&A after a von Kármán Lecture given before the rovers landed.)

In light of the risk that the panels would not reopen, he said (to paraphrase) that he could not conceive of a circumstance that would justify taking such a risk. And of course the dust is "sticky," so the potential benefit might be very little.

TTT

Posted by: centsworth_II Jun 22 2007, 02:38 PM

I'd find it hard to believe that there is even a way to do this.
I would assume they were designed to lock in the open position.
I'm sure it would take a whole different design, with different latches,
and motors to accomplish this. The intent was to open the panels
and leave them open. The design would have been the minimum
required to do this reliably and nowhere near as complex as that
needed to reclose and reopen them.

Posted by: RobertEB Jun 22 2007, 03:00 PM

I don't know if they lock in place or not. I would probably design them to do so if I was in charge.

If they don't perhaps they could try shaking the dust off as a last ditch effort.

However, when Spirit does finally die, I would hate to see her die with her panels stuck up. Doesn't seem fitting for a rover that has done so much.

When humans walk up to her one day in the future, I want them to see her sitting on Home Plate like she was as an explorer.

Posted by: Analyst Jun 22 2007, 04:00 PM

ITAR again. Well, it could be helpful to build solar powered nuclear bombs roving around. I am sure this could be helpful information for the ExoMars designers.
In the long term, ITAR will reduce the capabilities of the US aerospace industry to be competitive. Sorry, I had to say this.

Analyst

Posted by: fredk Jun 22 2007, 05:15 PM

Home plate? I want them to see her in the Promised Land!

Posted by: dilo Jun 23 2007, 01:34 PM

Well, seriously, I think that now that power is up, they should try move fast the rover in order to maximize exploration in the incoming months! This because frankly I doubt Spirit will survive another winter... moreover, last mission extension is approaching to the end (around Sol 1350, if I recall) and, while another year extention is possible (and auspicable), with actual budget issue there is the risk of a commandend shutdown within 5 months from now!

Posted by: djellison Jun 23 2007, 04:16 PM

While they have one mobile rover, it's unlikely the program will be shut down.


Spirit probably wont survive another winter - all the more reason to do the good science infront of us

Doug

Posted by: alan Jun 24 2007, 05:42 AM

Must be getting windy, a few more clean patches are visible between sol 1231 and 1234

Posted by: jaredGalen Jun 27 2007, 07:00 PM

All this cleaning might be timely but hopefully not fruitless, big storm a comin'....maybe.

http://www.space.com/news/070627_mars_storm.html

Posted by: dvandorn Jun 27 2007, 07:19 PM

Well, isn't it almost a truism that semi-global and global dust storms on Mars tend to occur as the planet approaches and works through its equinoces? Those are the times when the most extensive atmospheric transfer between the poles occurs (as CO2 sublimates off the cap approaching summer and condenses onto the cap approaching winter), and so generates the greatest global winds.

We've survived regional storms since the MERs landed, we can only hope that this storm (and any others that may pop up over the next couple of months) will remain regional and not go semi-global or global. We could still see both rovers die within days of each other if a global dust storm of the extent, say, of the 1971 storm were to develop.

Do note, though, that the rovers might well become cleaned by the more energetic winds to an extent that they *could* survive even a major dust storm. The HiRISE color image of the Viking 1 lander, for example, demonstrates that it is still primarily non-dust-covered, and we know it has endured several global dust storms. Depending on the rate of deposition vs. the rate of cleaning during such a storm, we might be able to get the rovers to advantageous slopes and weather a storm, as we have weathered Martian winters.

-the other Doug

Posted by: BrianL Jun 27 2007, 07:34 PM

Well, just in case this turns into a poll, I'm going to join the deposition camp now. Clean-sweeping burned me last time and I still haven't forgiven it. Don't even get me started on my feelings about the far side of the crater.

Brian

Posted by: David Jun 27 2007, 09:09 PM

Let's say we have the most optimistic scenario -- the dust in the wind gets blown by, and whatever dust is on the rover gets blown off -- how much would power drop, not from the dust on the rover, but the dust in the atmosphere? How long would the storm have to last before the rovers would become irrecoverable?

Posted by: helvick Jun 27 2007, 09:57 PM

Assume for a moment that the dust on the panels has reduced efficiency to 75%. The numbers for in and around now for Spirit would be:

So things would have to get very bad for this to be lethal right now. The highest Tau values we've seen so far are 1.84 for Opportunity (Sol 489) and 1.53 for Spirit (Sol 511) .

On the plus side the drop in Tau reduces the power loss as a result of shade within Victoria.

Posted by: fredk Jun 27 2007, 10:15 PM

Those numbers are interesting. When the tau increases from 0.9 to 1.5, the direct sunlight ("beam") drops by almost half, while the total available power drops less than 20%. Unless I've missed a square root, that means that a lot of the attenuated direct sunlight eventually makes it to us as scattered light, ie the sky gets a lot brighter.

Posted by: djellison Jun 27 2007, 10:26 PM

No - thats what happens, the direct drops, the indirect increases. For 'close ops' to a cliff, you'd want a clean rover, but a filthy sky

Doug

Posted by: helvick Jun 27 2007, 10:40 PM

As Doug says that is what happens - as the dust levels rise the direct beam insolation falls off pretty rapidly in an exponential decay curve (~exp(-tau) ) but the diffuse light actually rises initially and only starts to drop after around Tau ~ 1.8. The exact detail is I used for the above is from the formulas from this paper by Applebaum and Landis http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19940010257_1994010257.pdf

Posted by: Tom Tamlyn Jun 28 2007, 03:33 AM

Fascinating to read in the Applebaum & Landis paper the discussion of dust accumulation ("There may be removal of dust by wind as well as deposition"), and the possibility of designing solar arrays that could "flap" to remove dust. See pp. 12-13.

How high are the values of Tau for the biggest Martian dust storms, like the one encountered by Mariner 9 in the first months of its orbital mission?

TTT

Posted by: dvandorn Jun 28 2007, 04:07 AM

Or, more specifically, what was the greatest tau value recorded by the Viking landers when they endured major global dust storms? Each went through at least two major dust storms, and I know that *some* estimate of tau during those periods has been made.

Also, I know I've seen sequences of Viking lander images showing dust buildup after dust storms. I'd be interested in seeing those again, to get a feel for the kind of short-term buildup we may be looking at for our rovers.

-the other Doug

Posted by: fredk Jun 28 2007, 04:09 AM

http://marsrovers.jpl.nasa.gov/mission/status_spiritAll.html#sol1226
Another cleaning has occured. Power has risen to 738 watt-hours!!

Posted by: Jeff7 Jun 28 2007, 04:53 AM

Most excellent indeed.


The new Mars forum question:

"How many MERs will be working when MSL lands?
0, 1, or 2

Posted by: edstrick Jun 28 2007, 05:57 AM

Tau values were made by Viking Landers based on pre-programmed solar brightness observations. When the sun wasn't visible at exposure settings used, the values are lower limits. I *think* values of optical tau over 6 were indicated. Scene brightness levels dropped DRAMATICALLY, with darker horizons than higher skys and with more or less no shadows. Many/most of those images were badly underexposed Of course, once new exposures were selected and upllinked, the opacity dropped a lot, and the images were badly whited-out.

Thermal infrared tau values were measured from orbit with the infrared thermal mapper, a multi-channel radiometer and are about 1/10th (as I recall) the optical values.

Pre-Viking data are poor. Mariner 9 data was re-analyzed but I don't recall results and the worst of the storm was 2 1/2 OR 3 MONTHS before Mariner arrived.

Posted by: helvick Jun 28 2007, 06:36 AM

I don't have precise data but again there are approximation formulae in "Solar Radiation on Mars - Update 1991" J. Applebaum, G.A. Landis. (NASA Technical Memorandum #105216) for both of the 1977 global storms that yield optical depths by latitude and LS. Both of these peak at around 5.

That should equate to around a 70% loss in insolation which in turn should equate to about 1.5-2 f/stops from an exposure POV. That would be noticable shouldn't have caused dramatic under/over exposure of images so I wonder if the model underestimates the values? Any ideas?

Posted by: Analyst Jun 28 2007, 09:53 AM

This should be enough for the next winter (on a slope), shouldn't it?

Analyst

Posted by: helvick Jun 28 2007, 11:34 AM

738 Whr means she is still losing about 25% due to dust. Last summer at peak when she was generating 956 Whr the dust loss factor was around 5%. So she's getting cleaner but I don't think that surviving the winter is guaranteed yet. She bottomed out at 280Whr in mid winter at Low Ridge so right now we'd be looking at around 220Whr for the minimum next winter assuming nothing else changes (and dust deposition follows last years pattern).

Posted by: helvick Jun 28 2007, 11:45 AM

Interesting mix up of terms there - Tau and Dust Factor are not the same thing, looks like someone left out part of the sentence.

Posted by: dvandorn Jun 28 2007, 04:01 PM

Remember, too, that we're not just talking about a pretty straight-line graph in which the amount of dust entrained in the atmosphere relates directly to the amount of dust deposited on any given surface. There are a lot of microclimatological effects right along the surface that greatly impact dust deposition rates. If we were to park Spirit on top of El Dorado for a winter, for example (and I know, it would never happen, it faces the wrong way, etc.), you'd likely never survive because the hills force a turbulence that drops dust out of the air selectively onto the El Dorado formation.

IMHO, Spirit spent last winter in a place that tends to collect a little more dust than other places within reach. If she can claw her way up the side of a hill that faces into the prevailing winter winds, as opposed to sitting in a "deposition sink," she might have a better shot at surviving her next winter. But if she stays exclusively in the Home Plate area and doesn't get very far from it, the deposition rate may be just high enough to kill her without an extraordinarily vigorous cleaning event just before the onset of winter.

-the other Doug

Posted by: centsworth_II Jun 28 2007, 06:15 PM

If Spirit makes it to next winter, I think they'll take
a lot more care getting her into the best position
possible, as opposed to the rushed job last winter.
I wonder how far the positioning last winter was
from "perfect", how much better could they do
strictly from an angle-to-the-sun standpoint.

Posted by: djellison Jun 28 2007, 06:24 PM

They didnt want to do a rush job last time - remember they were trying to get to McCool hill which would have been amazing - but the stuck wheel, and then the Tyrone sand trap...things went against the rover so they had to get somewhere, fast.

Doug

Posted by: centsworth_II Jun 29 2007, 05:53 AM

I didn't mean to imply that they planned it that way. I'm presuming
that the result was a less than optimal, but still adequate, positioning
for wintering. My question is, how much better could they do next
winter in terms of positioning for solar energy gathering? Is there a
lot of room for improvement, or did they get pretty close to optimal
positioning in spite of the difficulties last winter?

Posted by: djellison Jun 29 2007, 08:37 AM

Well - with a stuck wheel they can't really climb onto the sorts of slopes that would be much better than Low Ridge haven. 20-25 degrees would have been better I would have thought - but the rover just can't get to that sort of terrain any more.

Doug

Posted by: BrianL Jun 29 2007, 12:55 PM

Even if the slope is rock with no significant sand to drag through?

Brian

Posted by: djellison Jun 29 2007, 01:05 PM

I'd say so, yeah. You drop not only 18% of your traction, but add a whole lot of drag even on rock. Slightly moot point given that there isn't a lot of exposed rock without sand involved near Spirit.

On the other side of the planet they've said that if they go into Victoria, then have a wheel fail while inside, it would be very hard to get out again.

Posted by: fredk Jun 29 2007, 02:54 PM

But fortunately getting to a steeper slope may not mean having to drive uphill. If we find ourselves still on Homeplate by late fall, it should be easy to drive from the top of HP partly down the north edge, which would face the right way. I don't recall any figures for those edge slopes, but I suspect they're better than what we had at Low Ridge haven - was that only 10 degrees?

Posted by: centsworth_II Jun 29 2007, 03:04 PM

Strategy for getting Spirit on 25 degree slope:
Climb a rise up a less steep slope, then
descend on the steep side and stop.

Looks like good slopes in yellow circle.
Spirit should be there in time to winter.

Posted by: centsworth_II Jun 29 2007, 03:07 PM

Right!

Posted by: helvick Jun 29 2007, 03:14 PM

The best they could do for the day that insolation is lowest ( around Ls 95 ) is to tilt to ~34.6deg facing due north , that would result in about 31% more power than a horizontal panel on the same sol.

The initial tilt angle at Low Ridge was 10.8deg which gave them about 15.7% more power than a horizontal panel on that day.

34 degrees is probably way to dangerous but a 20deg slope should be possible and that would yield a 25% increase in power.

The exact improvement varies over time as the suns declination changes - the above numbers are really only good for the weeks around mid winter.

Posted by: centsworth_II Jun 29 2007, 03:58 PM

That's a good time to have the maximum improvement!

Posted by: brellis Jun 29 2007, 05:28 PM

The subject of tilt begs the question, why don't the panels pivot to track the sun? I'd never thought about that. In the design process, if there's already a motor to unfurl the panels upon landing, couldn't that same motor rotate the panels and shake off dust in the process? I'm sure they thought about it, but I'm curious about the pros and cons.

Apologies if this question was addressed in an earlier thread. I'm a newbie, so I'm just learning how to read

Posted by: djellison Jun 29 2007, 05:39 PM

The dust probably wouldn't come off if you tilted the panels - it's fairly clingy. The motors only work one way ( I think) - I think they lock in place on deployment. And of course, what do you do if you end up with an array stuck up at an angle.

Doug

Posted by: Tom Tamlyn Jun 29 2007, 06:15 PM

Further to the same point, the deployment motors were only expected to work once. Designing and building them so that they would have continued to operate reliably in the Martian environment throughout the mission would have been something else.

TTT

Posted by: brellis Jun 29 2007, 09:11 PM

Ahh, that's the part I wasn't thinking about -- that, and using the motor continuously probably drains more power than you'd gain from tracking the sun. Then, at some unknown point the motor dies, and what if it freezes at a sunrise or sunset position. Well, I'm just glad I wasn't making that particular decision during the design process

Posted by: alan Jun 30 2007, 05:14 AM

Cleaned Again: Spirit Self Portrait

http://marswatch.astro.cornell.edu/pancam_instrument/adeck3.html

Posted by: Nix Jun 30 2007, 06:28 AM

woaw.. she looks good!

Nico

Posted by: Shaka Jun 30 2007, 07:19 AM

But she could look better! Come on you devils/angels! You missed a few spots.

Posted by: kenny Jun 30 2007, 08:34 AM

I never appreciated how variable the dust covering could be from panel to panel until I saw that pan, alan....

Posted by: Oersted Jun 30 2007, 09:35 AM

Looks like the cleaning has been more efficient in the center panels (or maybe they were cleaner to begin with?). If it is turbulence that helps clean the panels, maybe it would be a good idea to have "turbulence provokers" on the sun panels of future rovers? Maybe wispy stalks standing up from the rover deck, thin enough to not cast shadows but still churning up the air. Just brainstorming here...

Posted by: CosmicRocker Jun 30 2007, 05:37 PM

Being from sol 1229, I think that self portrait was after the first cleaning of this season. The second cleaning, which boosted Spirit's output to 50 W-hrs greater than Opportunity, was on sol 1233. We have gotten only a few navcam images of parts of the deck since then, so it is difficult to see what may have changed.

Posted by: fredk Jul 1 2007, 10:43 PM

From the latest http://www.planetary.org/news/2007/0630_Mars_Exploration_Rovers_Update_Spirit.html this description of the sol 1224 cleaning event:

Posted by: Shaka Jul 2 2007, 12:59 AM

Yes, only a devil would tidy up so haphazardly.

Posted by: TheChemist Jul 2 2007, 10:53 AM

Looks like http://www.unmannedspaceflight.com/index.php?showtopic=762&st=45&p=6503&=%23entry6503# will finally get actual data to verify their simulations

Posted by: alan Jul 4 2007, 07:16 PM

Dust from the storm in Meridini appears to have been transferred to Spirit's side of the planet.

The shadows are getting weaker

Scattered sunlight is visible in the navcams taken recently

Posted by: hortonheardawho Jul 4 2007, 09:29 PM

sol 1204 - 1244 L2 comparison of Husband Hill:


http://www.flickr.com/photos/hortonheardawho/715526409/

Posted by: Floyd Jul 4 2007, 09:34 PM

Horton, that is dramatic. A layer of dust almost completely hides the dark sands. And in just a few days. Wow

Posted by: djellison Jul 4 2007, 09:36 PM

Bloody hell! The way the whole area beyond the middle-ground horizon is softened makes me think we're seing one of the DD's that deteriorates into just a swirling body of dust heading across the foot of El Dorado. Well spotted.

Doug

Posted by: alan Jul 4 2007, 09:58 PM

Ah, that explains why the color images of the left and right sides of El Dorado are so different.

Posted by: hortonheardawho Jul 4 2007, 10:50 PM

Ah, indeed:

http://www.flickr.com/photos/hortonheardawho/715637871/

The right frame is 98 seconds after the left -- which seems to be clearer -- but still dusty.

SO, a dust devil was moving right to left?

Posted by: fredk Jul 5 2007, 04:03 AM

I'd say left to right. The gust could easily have passed before the right side was imaged.

Interestingly, I'm pretty confident you can see another gust (maybe the same one?) just below the foreground "horizon" in http://marsrovers.jpl.nasa.gov/gallery/all/2/p/1244/2P236804528ESFAUATP2379L7M1.JPG That foreground horizon is about the same distance in http://marsrovers.jpl.nasa.gov/gallery/all/2/p/1244/2P236804431ESFAUATP2379L7M1.JPG but it looks much darker than in the previous frame I posted.

All this really makes me wonder what it would be like standing there with the rover. We know the rover must only image a small fraction of all dds/gusts that pass by. How dynamic or "alive" would the air be at 1pm on a summer afternoon? Would something be happening somewhere around you at all times?

Posted by: Pertinax Jul 5 2007, 12:32 PM

Well noted indeed, and what a catch.

I was just going to note that the 1244 view that Hort posted looked less to me like deposited dust and more like dust being raised and actively blown along on the wind at the time of the picture. I'll say -- miss one day for lack of broadband and you miss out on worlds of adventure!

Cheers,


-- Pertinax

Posted by: PDP8E Jul 6 2007, 07:36 PM

Hi All,

Is there a website of returned engineering MER data (similar to returned image data) ??

It would be nice to see the per sol: Wh, temps, amps, -etc

tnx

Posted by: climber Jul 8 2007, 09:42 AM

Sorry All, I was away and missed the whole thing, DD & big storm. May be you've talked about it but as I'll need 2 days before been updated on the whole UMSF , I'd better ask this question now : can the event that have cleaned Spirit as described by SS be a premice of the Big Storm instead of a "normal" dust cleaning event ?

Posted by: djellison Jul 8 2007, 09:51 AM

Yes - cleaning is usually thought to be due to high winds

Dust storms are thought to cause high winds

Thus - major cleaning and dust storms tend to be closely related.

Maybe it's something to do with the change in illumination - BUT - Opportunity looks utterly A1 clean right now.

Doug

Posted by: climber Jul 8 2007, 10:02 AM

I don't know how it works, a meteorologist can help on this, but I was thinking of a kind of depression created by the storm that would have led it by a few hours. Does it make sense?

Posted by: Stu Jul 8 2007, 12:45 PM

Giving another talk later this week and would appreciate advice on this pic I've made for it...

With all the extra atmospheric dust is the sky too blue? Not blue enough? Not going for 1000% scientific accuracy this time, just wanting to try and put across the beauty of Mars...

Posted by: Oersted Jul 8 2007, 05:40 PM

Just checked out my window here on Mars, and yes, it looks about right.

Posted by: hortonheardawho Jul 8 2007, 06:08 PM

Stu, I would make the sky bluer around the sun. It is, after all, a Martian sunset.

I noticed that the sundial shadows are most distinct in the L6 image when the base image was taken - which means the direct light was bluer than the indirect light.

Posted by: Stu Jul 8 2007, 06:49 PM

Thanks hort, bluer it shall be I was just unsure about the optical effect of all the "storm dust" in the atmosphere, you know?

Wish I could see that for real... how cool would it be to see that Sun sinking behind those hills and then see Earth shining in the twilight...

Hey, just noticed this is my 1000th post!

Posted by: Ant103 Jul 10 2007, 10:27 PM

New pics on the exploratorium for Spirit

Look at the panel :
http://qt.exploratorium.edu/mars/spirit/navcam/2007-07-10/2N237339278EFFAUCMP1665L0M1.JPG
It seem to be cleaned, isn't it?

Posted by: alan Jul 10 2007, 10:46 PM

Yep, another cleaning event for Spirit's solar panels.

Spirit's forward hazcams weren't so lucky

http://qt.exploratorium.edu/mars/spirit/forward_hazcam/2007-07-10/2F237337944EFFAUCMP1214R0M1.JPG

Posted by: monty python Jul 11 2007, 02:49 AM

Yikes! Thats a spectacular and unique amount of dust accumulation. I wonder what percentage of total erosion and deposition occurs during these periods of near global dust storms?

Brian

Posted by: slinted Jul 11 2007, 03:35 AM

Looks like the winds picked up sometime between 1247 and 1248, which might have also been the event that dusted up both front hazcams.

Here's the capture magnet, in L4:

Posted by: alan Jul 11 2007, 03:46 AM

good eyes slinted

A comparison between 1238 and 1250

By examining the circled areas you can tell that the latest cleaning event the wind blew the dust in the opposite direction as before.

Posted by: djellison Jul 11 2007, 07:44 AM

The Silica Valley tracks have been virtually wiped out in the last couple of weeks. Amazing stuff.

Doug

Posted by: Stephen Jul 11 2007, 09:16 AM

That raises the question of whether there would be any useful advantage in having dust covers (or some equivalent) for cameras in future (long-lived) Mars landers like MSL. Or would such things be more trouble than they were worth? (Eg one more thing to break down on an aging lander.)

======
Stephen

Posted by: djellison Jul 11 2007, 09:23 AM

1200 sols without significant dust deposition on lenses - and workarounds for when there are anyway (new flatfields onboard etc). For a 600ish sol Primary mission for MSL - such a thing isn't going to be necessary or required. Yes - I know it will likely last MUCH longer, but the primary mission is what you design for.

Doug

Posted by: Ant103 Jul 11 2007, 11:31 AM

I don't know where put this : here or on the Storm topic?

But, I've updated my following of sky opacity from Spirit site. Here is the picture :
http://astrosurf.com/merimages/Images_de_spirit-2007.html#atmopacite

The rising dust quantity is particulary clear on the Sol 1248 (see Grissom Hill).

Posted by: climber Jul 11 2007, 02:34 PM

Clear is actualy not the right word !

Posted by: climber Jul 11 2007, 02:36 PM

May be OT but do you know the margin engineers actualy take? Is it 2x? 10x?

Posted by: djellison Jul 11 2007, 03:02 PM

I'm sure I heard 3x (i.e. 270 sols for MER )

Doug

Posted by: fredk Jul 11 2007, 03:14 PM

Thanks for that, Ant. Do you know how consistent the local times of day are for the individual frames? Ie, are they all taken at near 12:00, for example?

These images are autostretched, of course. Once the calibrated data are in, I'd love to see a version of your montage using absolute illumination levels, so you could directly see how much darker it got during the storm.

Posted by: Ant103 Jul 11 2007, 03:26 PM

Hum... I don't know if the rover takes the pictures at the same time. I hope so because I've remarked that they take the exactly same portion of the sky with Grissom Hil at the left. To reveal colors, I apply exacctly the same processing to have a regular following, but I'm aware that ambiant light have an influence on the exposure. And this is one of the parameter that I can control to have a quite perfect series of pictures and compare them.
But, I hope that this board show -partially- the evolution of dust level in the martian air.

Posted by: mhoward Jul 11 2007, 03:44 PM

There's more than that going on: the raw JPGs are automatically brightness-stretched before they get to us, so the brightness levels in the individual images are more or less unpredictable. If you are using the raw JPGs, you can't reliably conclude anything about the brightness levels. Still, it's an interesting series of images.

Posted by: fredk Jul 11 2007, 04:01 PM

I should add that although the autostretching means you can't trust the overall brightness and colour of the images, you can trust the change in relative brightness across individual images. So that "inversion" effect, where in the early sols the sky is brighter near the horizon, but more recently and especially during the storm the sky is darker near the horizon, is real. Also we can probably trust the increased haziness of the distant peak at later sols.

Posted by: Ant103 Jul 11 2007, 04:10 PM

Okay

Two other board who show Oppy's and Spirit's panels. To the left, many time before the storm. To the right, just after the maximum level of it :

We can se quickly that solar panels are more clean than the others sols ago.

Posted by: mhoward Jul 11 2007, 04:12 PM

True, you can make some very broad qualitative observations; but probably not much, and not very reliably. And even then, you must be careful to take other variables into account, like time of day, to say nothing of filter choice (for Pancam).

Posted by: helvick Jul 11 2007, 05:37 PM

I heard that somewhere too but it always depends on what you mean by "margin".
The solar panel requirements for the rovers specified that they had to deal with a predicted dust loss rate of 0.18% per Sol which left them at around 700Whr after 90 sols, 600 after 180 sols and 500 after 270 sols. If that rate had been seen consistently throughout the mission with no cleaning Spirit could have lasted until somewhere between sol 750 and 800. You might read that as a 7 or 8x margin.

However the initial power requirement was to be able to deliver a minimum of around 350-400 Whr/sol at 90 Sols so the initial design really only gave about a 2x margin after 90 sols and given that a single storm like the one we are seeing right now would reduced that to zero, you could argue that there was no margin at all.

Posted by: climber Jul 11 2007, 06:21 PM

So it'll be 1800 Sols for MSL. Well, they may be have to think about a way to protect lenses for that long afterall.
BTW, for a launching date in summer 2009, MSL would be around by summer 2015 with only 3 times is scheduled life... you'll have a new shed by them

Posted by: ElkGroveDan Jul 11 2007, 06:27 PM

Then we will have to start calling him Doug "http://www.youtube.com/watch?v=HLjS3gzHetA" Ellison.

Posted by: djellison Jul 11 2007, 06:34 PM

THREE sheds. Technically I had a little brick one at the end of the garage, the woodern office one...and then I'll probably get a small JCB in and go for some sort of large basement in the garden

Doug

Posted by: fredk Jul 12 2007, 04:29 PM

Dramatic changes on the ground, too. Compare these pairs of navcams from sols 1239 and 1250:

http://marsrovers.jpl.nasa.gov/gallery/all/2/n/1239/2N236362508EFFAUATP0755R0M1.JPG
http://marsrovers.jpl.nasa.gov/gallery/all/2/n/1250/2N237338065EFFAUCMP0765R0M1.JPG

http://marsrovers.jpl.nasa.gov/gallery/all/2/n/1239/2N236362590EFFAUATP0755R0M1.JPG
http://marsrovers.jpl.nasa.gov/gallery/all/2/n/1250/2N237338152EFFAUCMP0765R0M1.JPG

http://marsrovers.jpl.nasa.gov/gallery/all/2/n/1239/2N236362753EFFAUATP0755R0M1.JPG
http://marsrovers.jpl.nasa.gov/gallery/all/2/n/1250/2N237338202EFFAUCMP0765R0M1.JPG

The local times of these pairs are only about 15 minutes apart, so the solar incidence angle is essentially the same, although there is a bit of movement of the rover between sols.

The rover tracks are much less prominent now - it seems to be mostly due to albedo effects. Exposed light areas have been covered in darker dust. And generally, the whole ground has taken on a "mottled" look, which I recall from after the previous big cleaning event near Larry's Lookout. That mottling seems to do a great job of hiding the older tracks - some of them are almost invisible now.

I can think of a couple explanations for the mottling - perhaps the thickness of the lighter dust varies like the mottling pattern, so when the wind removes light dust the pattern is exposed. Or it may be that the wind generates eddies or turbulence that actually remove dust in the mottled pattern.

Posted by: Ant103 Jul 12 2007, 05:43 PM

Hum... Interesting. At many places around the rocks, the ground has darken, and in the same time, at local elevation of the ground (top of ripples), the ground has lighten. And, I don't know if is it my eyes who play me a trick, but, I see very faint dark trails.

Posted by: Pertinax Jul 12 2007, 06:07 PM

The recently windswept areas look (to me at least) to be areas where the lighter sulfate (and silica?) rich soil is now much less covered by / peaking through the darker fines (which themselves accumulated in crevasses and in the lee of objects).

-- Pertinax

Posted by: alan Jul 12 2007, 06:51 PM

I wonder how much of the apparent change in albedo is due to changes in lighting. Although the local time is similar the lighting has been changed due to the increase in tau, which according to http://www.unmannedspaceflight.com/index.php?act=Attach&type=post&id=11119 has more than doubled at Spirit's location during the two weeks.

More diffuse lighting, caused by the light being scattered by dust in the atmosphere, could increase the importance of albedo vs. the slope of the ground or dust drifts relative to the sun.

Posted by: fredk Jul 12 2007, 07:18 PM

Good point, Alan. Still, there are plenty of very smooth areas, where the slope is more or less constant, which have become mottled. But definitely the more diffuse lighting would make relief features like the tracks less noticible.

Posted by: slinted Jul 12 2007, 11:17 PM

I'm glad we keep having good reason to come back to this thread. Spirit cleaner? Cleaner yet as of sol 1252!

Here's the sweep magnet sol 1251->1252, in L7, showing the strength of the winds (this one probable rivaled the big cleaning back on sol 421) picking up dust from one side very well, and dumping/spreading it down onto the other side...like an arrow, pointing in the direction of the winds.

http://www.lyle.org/~markoff/collections/2P237419883ESFAUCMP2121L7M1_237513520full.gif

The area around Spirit shows some effects from the wind as well (even the dust mottling on the front haz's changed):

http://www.lyle.org/~markoff/collections/2F237423637EDNAUCMP1121L0M1_237511260.gif

Posted by: Pando Jul 13 2007, 05:05 AM

How many Mars environment simulators do you need, really?

Posted by: MarsIsImportant Jul 14 2007, 01:46 AM

I am absolutely amazed! This is the kind of weather that I thought would kill the rovers. Instead, they are going to live a lot longer! I really believe that the major limiting factors for these machines are the wheels. Nobody thought that these machines would last any where near this long, so they didn't design the wheels to last for years.

Posted by: vikingmars Jul 18 2007, 10:11 PM

Dear Ant,
Superb processings !
Here is the same kind of cleaning event for the VL1 deck after the sol 1742 dust storm.
Here are 3 images taken on sols 1321 - 1742 -1987 : a "before - after" sequence.
Enjoy !

Posted by: vikingmars Jul 18 2007, 10:16 PM

Dear Fredk
How interesting are your comparisons !
Here is the same kind of dust removal event spread over a 6-year period for VL1 (1976-1982) : see all the dark soil patches on the drifts and the new ripples around some rocks after the sol 1742 dust storm event...
Enjoy !

Posted by: fredk Jul 19 2007, 04:59 AM

Glad you liked my comparisons, Viking. Here's one more.

Sol 1255 and 1257. It seems the strong winds are continuing. You can see that much of the dust on the hazcams has been cleared away. But if you look closely at this animation, you can see movement on the ground:

If you look at the area I circled in black in the image below, you can see light splotches that move collectively towards the lower right, which corresponds to roughly towards the south.


What's really remarkable is if you look in the area I circled in white, you can actually see tiny ripples moving again towards the lower right. I'm quite sure this isn't just due to different lighting, since these images were taken within 30 seconds local time of each other, and tau was only slightly higher on 1257.

To my recollection this is the first observation of moving ripples. Even while the rovers face potentially their greatest threat, they can surprize us with amazing results.

Posted by: ElkGroveDan Jul 19 2007, 05:46 AM

Good eye Fred. Additionally you can actually see several light colored pebbles being exhumed in that large lower dark colored ripple.

Posted by: hendric Jul 19 2007, 05:11 PM

also, in the Viking picture you can see a rock face starting to emerge from the dune below the large rocks on the left.

Posted by: vikingmars Jul 19 2007, 10:33 PM

Sorry, but this is just an illusion. Not a rock emerging, but rather a slump in the drift material immediately in front of and to the right of center of the big boulder (named "Big Joe"). As you saw it indeed, this slump was not present when Viking 1 landed and is a good proof that modification of the surface is currently active. It may have been caused by a "Marsquake", lander vibrations while working on the surface, loose soil...

Posted by: CosmicRocker Jul 20 2007, 04:37 AM

Congratulations to you guys watching for these changes. Slinted, fredk, and vikingmars, thanks for the revealing images and animations. They have added a new dimension to my Mars experience.

Posted by: CosmicRocker Jul 24 2007, 04:47 AM

I didn't want to start a new topic for this, but what's up with the pancams that appeared at the exploratorium today? My update via MMB tonight has exceeded 50 MB, and it appears I am only half through it. I am getting a large number of very old images. Is Spirit cleaning low priority images from its flash memory? I could swear that I read somewhere that the 7/23 comm session returned a small amount of data from the rovers.

It finally ended after generating a large number of anaglyphs and false color images. It appears that over 80 MBs of jpegs were downloaded.

"Update complete Mon Jul 23 23:36:02 CDT 2007
558 images downloaded 4 errors."

Posted by: alan Jul 24 2007, 05:37 AM

Thats odd, when I checked using MMB I got no new images found. The images from 7/23 must be old images reposted.

Posted by: OWW Jul 24 2007, 12:32 PM

For some reason MMB's "Check for new images" doesn't detect the 2007-07-23 folder. Forcing the update with "Advanced update" worked though.

But a lot of these "new version" images are worse than the original ones! Lots of data dropouts where the old ones were complete! Totally wrecked a lot perfect generated images.

Posted by: alan Jul 24 2007, 04:17 PM

Doing the advanced update from JPL using the sols of the messed up images may fix those.

Posted by: OWW Jul 26 2007, 11:10 AM

Check out the changes in the latest Spirit Hazcam image. The wind must be blowing Very hard:

http://qt.exploratorium.edu/mars/spirit/forward_hazcam/2007-07-20/2F238218896EFFAUCMP1159L0M1.JPG
http://qt.exploratorium.edu/mars/spirit/forward_hazcam/2007-07-25/2F238662645EFFAUCMP1159L0M1.JPG

Posted by: abalone Jul 26 2007, 12:28 PM

Looks like the dune crest near the left front wheel had moved about 1-2 cm in 5 sols

Posted by: elakdawalla Jul 26 2007, 04:26 PM

Whoa! Well spotted!

--Emily

Posted by: CosmicRocker Jul 27 2007, 04:57 AM

That's a continuation of the changes initially spotted by fredk last week. The 3 frames over 10 sols animation is nice. There are some other frames that could be forced into the animation, but these three frames provide two roughly equal time steps of 5 sols each...1255-1260-1265 I'm watching it on my PC right now, but these animations drive me to the brink. I can't force the gif below the file size limitation without terribly degrading its quality. I'm sure someone else will manage to post one.

Posted by: Astro0 Jul 27 2007, 07:42 AM

Had to scale down a bit and clip top and bottom, but the 13 frame file comes in at just under 3mb.
http://www.cdscc.nasa.gov/Temp/dune_move.gif
EDIT: Sorry, for some reason the server is running very slow at the moment. Apologies if you are trying to download.

A small two frame reference.
Lots of movement.

Astro0

Posted by: Gray Jul 27 2007, 03:21 PM

Thanks Astro0.
It did take a while to download, but it's a very revealing animation. As you said - lot's of movement.

Posted by: CosmicRocker Jul 28 2007, 05:51 AM

This simple animated gif is what I was trying to post. I just wanted to keep the time steps roughly equal and the image size maximized. I had to crop it down to the area where most of the movement is taking place. ...1255...1260...1265...

Posted by: brellis Jul 28 2007, 06:13 AM

that's the best visualization of the local effect of the storm I've seen. thanks for squishing it thru the portal

Posted by: alan Jul 28 2007, 07:49 AM

Horizon comparison 1254-67

Posted by: Oersted Jul 28 2007, 10:54 PM

Cosmicrocker, that is just excellent.

So much for those theories about the sand only shifting over millenia on the surface of Mars. I never understood those ideas anyway...

Posted by: Tom Tamlyn Jul 29 2007, 03:27 AM

http://www.unmannedspaceflight.com/index.php?s=&showtopic=4309&view=findpost&p=95928

Alan,

Thanks for that "Lonely Mountain" diptych. It's one of the most evocative storm images yet.

TTT

Posted by: Phil Stooke Jul 29 2007, 03:49 AM

Oersted:
"So much for those theories about the sand only shifting over millenia on the surface of Mars. I never understood those ideas anyway... "

They weren't theories, they were observations. No dune, no drift, nothing but the thinnest surface layer of dust, has ever been observed to move before in this way. This is a unique and very important observation. Thanks, Cosmicrocker.

Phil

Posted by: CosmicRocker Jul 29 2007, 05:44 AM

Well, fredk was the guy who was on the lookout at the time, and who first noticed the changes. His earlier comment and animation motivated me to watch for another way to display it.

It is too bad Opportunity was so energy deprived that she couldn't capture similar images. With a little luck, she should be able to give us some before and after views that we can compare.

Posted by: Tman Jul 29 2007, 06:56 AM

Hey that's great! Another nice piece of Mars weather behavior.

In what direction has the wind blown here?

Posted by: edstrick Jul 29 2007, 08:17 AM

The Viking 1 lander was operating in it's "eternal" extended mission mode and taking very slowly accumulated panoramas (one segment at a time, transmitting in the blind to earth) and "monitoring" images, repeated in a much shorter cycle, of a few specific targets including a few sampler-arm deposited "conical piles" of dirt, dumped in at least one case on top of the end of a largish nearby rock.

Just before the lander died of battery failure and command error, a major, presumably globe-encircling dust storm developed and at least one of the dust piles was nearly blown away by presumably storm associated winds.

Whether the extremely limited data from the lander before it died showed any changes in surface features that were not disturbed by the lander, I don't know, but I don't think any were reported. Worth looking at the limited data again, I'd say.

Posted by: antipode Jul 29 2007, 09:09 AM

From the gif, from what azumith is the wind coming?

P

Posted by: Tman Jul 29 2007, 04:14 PM

Ah Fred mentioned it already. It looks like we've had here wind from north roughly.

Posted by: fredk Jul 29 2007, 08:44 PM

CosmicRocker - thanks for crediting me on the moving ripples!

It's also good to see yours and other animations of this. Though there's nothing really new in my new animations here, I'll post them anyway. I've kept the resolution at 100% and included all frames that showed any changes, so I've had to break the frame into two UMSF-sized (< 1MB) pieces. Both movies show sols 1250, 51, 52, 53, 55, 57, 59, and 65, and the lighting does vary between frames somewhat. I did a bit of a gamma tweak to bring out detail in the shadows.

This first movie shows the most obvious moving ripples. I don't think anyone has mentioned that they actually were formed by the rover wheels - you can see this most clearly in the first frame. So it's less surprizing that they should be modified by the wind. Still, it's very cool to see the wheel tracks dissolve in a span of two weeks. Notice the tiny cross-ripples that appear in the remnant of the main track at centre frame by the end of the animation. I also like the way the drifting dust "flows" around the rocks in the foreground.

Still, there's definitely movement in the ripples in the upper left where I think are no tracks.

Posted by: fredk Jul 29 2007, 08:54 PM

Here's part 2. This area clearly has no rover tracks at all, and there's obvious movement in little ripples all across this view. It's also cool to see the little pebbles being uncovered and recovered in the lower left part of the view.

Posted by: Shaka Jul 30 2007, 01:46 AM

Outstanding, Freddo!

Posted by: brellis Jul 30 2007, 02:46 AM

Like sand through the looking glass, so go the Sols our of Lives

Besides these documented shifts, I wonder if any precariously-hanging rocks/boulders might get shaken loose by the Storm. It may be prudent to take a close look at before-after pancams from both rovers.

Posted by: Oersted Jul 30 2007, 02:02 PM

Well, we´ve seen dust devils moving what is obviously sizeable amounts of dust around, and leaving long tracks across the surface.

Cool to see little drifts shifting along, but something that we would obviously see at some point, given our knowledge of the weather on Mars.

Posted by: MichaelT Jul 30 2007, 02:48 PM

Thanks fredk!
The moving dust is really an amazing sight! It would be great to revisit some of Spirit's old tracks to find out how much they might have changed.

Michael

Posted by: jamescanvin Jul 30 2007, 03:16 PM

That's not hard, Spirit is right next to loads of old tracks, some nearly 500 sols old!

Posted by: slinted Aug 3 2007, 11:31 AM

Spirit was able to return some rear haz images from sol 1272, the first taken since 1250. The wheel scuffs directly behind the rover have been completely erased/filled-in.

http://www.lyle.org/~markoff/collections/spirit_rearhazR_1250_1272.gif

Posted by: Tesheiner Aug 3 2007, 12:05 PM

Incredible!

There are some http://nasa.exploratorium.edu/mars/spirit/navcam/2007-08-03/. Do we have similar ones from older sols to make a similar animation?

Posted by: Floyd Aug 3 2007, 12:31 PM

This is of the http://qt.exploratorium.edu/mars/spirit/navcam/2007-06-16/2N235294627EFFAU00P1913L0M1.JPG, but the rover moved between shots. Moved back and to the right. Tracks mostly erased.

Posted by: Ant103 Aug 3 2007, 12:39 PM

Absolutely amzing
I can't believe my eyes!

Posted by: TheChemist Aug 3 2007, 12:44 PM

This is extraordinary !
At this rate of deposition, Eagle crater on the other side of the planet might be difficult to recognize now. Good thing Victoria is huge

Posted by: Ant103 Aug 3 2007, 02:47 PM

Floyd, I tried this animation (I have had to rotate one of the picture to have little corresponding points) :
http://www.studiolentigo.net/upload/anim-127-1272-soilvariations.gif
Caution : 1024x1024 px, 2.1 Mo gif animation!

Posted by: ugordan Aug 3 2007, 02:56 PM

Are you sure the tracks are being buried by dust? Seems to me the effect is primarily due to wind moving dust around. Amazing in any case.

Posted by: fredk Aug 3 2007, 03:17 PM

Ah, yes, deposition or clean sweep?

Seriously, I agree with Gordan here - we can actually see the process through the front hazcam animations posted above, with wind pushing little ripples along and erasing tracks.

We've heard in press releases that all the dust in the air would only be the thickness of a human hair or so if it all settled out, so that shouldn't be enough to have much effect on the topography.

Posted by: Tman Aug 3 2007, 04:13 PM

Amazing such change of rather deep tracks from Spirit.
The track from the stuck wheel has even got some nice ripples of sand.

That deserves some work to do with it. In such a way never tried before to get a "mosaic" with PTgui, but it seems to "work" too :-)

http://www.greuti.ch/spirit/spirit_1227_1272.gif

I would say most changes of pebbles between the two pictures in the GIF are due to the stitch.

Posted by: elakdawalla Aug 3 2007, 04:53 PM

It's "Gordan," fredk, with an "a." Those of us who were brought up on Sesame Street always want to type "Gordon," but he's not the same guy!

--Emily

Posted by: ugordan Aug 3 2007, 05:03 PM

Well, both names probably have a similar root so not that big of a deal... We also have the name Goran back here (more common actually), to make matters worse!

Posted by: fredk Aug 3 2007, 05:07 PM

Oops - mistake corrected! And I wasn't even brought up on Sesame street...

Tman, that's a beautiful animation. I had been saying to myself "if only I could geometrically distort these frames to match"...

Posted by: elakdawalla Aug 3 2007, 05:17 PM

I just looked at that animation, and it's amazing how much those tracks have been obliterated. Wow.

--Emily

Posted by: Ant103 Aug 3 2007, 05:52 PM

Tman : I have softens your animation (and reduce the size) :
http://www.studiolentigo.net/upload/spirit_1227_1272-softens.gif

Posted by: Tman Aug 3 2007, 06:13 PM

That's a nice idea, Damien. It will blow up the size of the file but I'm going to make such a GIF in full resolution too.

Here: http://www.greuti.ch/spirit/spirit_1227_1272_trans.gif It's ~ 4.2 MB

Posted by: ElkGroveDan Aug 3 2007, 06:48 PM

There's also one up on the MER press release page (Aug 1) that moves really nicely



Medium:
http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20070802a/20070801_Spirit_br2.gif

Large
http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20070802a/20070801_Spirit.gif

Posted by: nprev Aug 3 2007, 06:55 PM

Jeez. No wonder Meridiani's so uniform...pretty significant erosion given the fact that these events happen at least every five E-years or so. Implications here for the durability of the evaporitic substrate, and most of the rest of the planet must be pretty hard by comparison.

Posted by: john_s Aug 3 2007, 08:57 PM

Apparently this press release results, at least in part, from me mentioning the UMSF posts on this topic to Jeff Johnson from the MER team, over a beer last week. You guys were there first- congratulations!

John.

Posted by: jamescanvin Aug 4 2007, 02:36 PM

A day later than planned (I'm still trying to get all my processing software up and running again).

There is a bit of overlap between the A1272 navcams and those taken on A1250 from the same spot (AUCM). Of course camera moves a bit due to the differing elevations that it was pointed at so the match isn't perfect. Here's the gif.

http://www.physics.usyd.edu.au/~jcanvin/mer/1250_1272_compare.gif

Click for a full res version (1.9Mb)

Some quite dramatic changes.

James

Posted by: Steve Aug 4 2007, 03:40 PM

What I like about these animations is that they show the deposition is somewhat local. The dust seems to be depositing mainly in the hollows while on raised surfaces (see the little white rocks on the left frame) the dust is actually being blown off. The rovers are raised surfaces....

Steve

Posted by: Stu Aug 9 2007, 06:35 PM

Hmm, I thought Spirit would look dustier than this...

Posted by: gpurcell Aug 10 2007, 01:17 PM

Yes, this is my take as well. It looks more like dust being shifted around rather than new dust being added to the environment. Let's hope that continues....

Posted by: CosmicRocker Aug 10 2007, 03:54 PM

I would guess that the continuing, high tau values mean that most of the dust is still suspended in the atmosphere. I think that the material we see moving around the rovers is actually sand.

Posted by: PaulM Sep 4 2007, 11:59 AM

It has been suggested that without a cleaning event Spirit will not survive the next winter and that at Home Plate there is very little chance of a cleaning event.

My suggestion is that when Spirit has finished with the South side of Home plate then it should head for the "Promised Land" as soon as possible. I understand that the hill between Home Plate and the Promised land is fairly gentle and so is still climbable with 5 wheels.

Spirit experienced its first cleaning event at Larry's Lookout on the North facing slope of Husband Hill and so I am confident it would experience a similar cleaning event on the way to the promised land.

Posted by: djellison Sep 4 2007, 12:03 PM

We've had cleaning events right where we are now, just before the dust storm. There's not much point in trying to out-guess Mars when it comes to cleaning events. Having confidence in one particular slope or orientation to provide cleaning just is not wise. Nor is the presumption that between now and winter, we can make it half a km south over uncertain terrain. It would be far more sensible to continue exploring home plate for now, and use any one of the local north facing slopes that are part of, or are around Home Plate - perhaps even the Pitchers mound

Doug

Posted by: Jeff7 Sep 5 2007, 02:38 AM

Wow, it's still so dark there.


Indeed. I was wary about Opportunity wandering into Victoria's dark streaks. Good thing I was wrong about that. Those things were like a Martian car wash.
The fact that Home Plate isn't completely covered in dust must also say something about the winds in this particular area. El Dorado would probably have been a death sentence - no argument about deposition or "clean streak" there. But Home Plate looks pretty clean. Hopefully in that regard, Spirit will follow in its footsteps.

Posted by: PaulM Sep 5 2007, 12:12 PM

If I remember rightly Steve Squyres said about 6 months ago that Spirit would be finished with Home Plate within 6 months and would then be moving on. I think that I did read that the Pitchers Mound (or at least Goddard) was on Spirit's planned route.

What I would like to see however is Spirit moving onto a decent hill South of the Pitcher's Mound (on the way to the Promised Land) before the next Winter. My reason for this is the contrast between what Spirit achieved on the large hill known as the Western Spur in its first Winter and how little it achieved on the tiny Lowe Ridge last Winter.

I realise that circumstances forced a rapid drive to the safety of Lowe Ridge last Winter. However, I hope that with more planning time available Spirit will be on a nice North facing hill before next Winter and will have several 100s of metres of gentle slopes ahead of it to explore during the 6 months of the Martian Winter.

The Southern end of Home Plate remains for Spirit to explore. However I hope that Spirit will be finished with Home Plate within the next 3 months or so.

Posted by: djellison Sep 5 2007, 01:29 PM

We had months and months of planning when it came to the drive to McCool hill last winter - but we didn't make it because of what Mars threw at us. And yes - the plan may have been to move on 6 months later...6 months ago - BUT - that was before a near 3 month hiatus because of the global dust storm.

Spirit can not traverse steep slopes anymore. There isn't anywhere with a lot of gentle slope all in the same direction - apart from McCool hill, and we know what happened last time we tried to get there.

The reason it had a productive winter in its first year was because it never had less than 300 Whrs - enough for all the housekeeping plus driving and science. Second time around, it dropped to less than 250 and only had 5 wheel drive - enough for housekeeping and...that's about it. Even if they HAD made it to McCool hill, they wouldn't have been able to climb it in any way - it's unlikely they would have had enough power to even trundle around the gentle slopes at the bottom of the hill.

There are some small hillocks to the south - including the odd interesting one....but if you set out for them NOW - with the potential for Tyrone like sand traps on route - you would run a very large risk of getting stuck out on flat terrain somewhere south of Home Plate and dying because of a lack of slope. 10-20m/sol is all you can expect - and even when 'sprinting' one can typically expect one sol in two or three to be a driving sol.

From a scientific persepctive - yes - the terrain to the South looks interesting, but I would have though the prudent option from the bigger-picture persepctive is to stay comparatively local this winter, and, if we have a healthy vehicle next spring, set out south at that point. Realistically - we've barely started exploring home plate itself. There's many months of science to be done here before electing to move off.

Doug

Posted by: climber Sep 5 2007, 07:56 PM

Agree on your plan Doug. I'm a bit lost of where we are regarding seasons on Mars. If I'm right we're only a few days away from the 2nd Marsian year on Mars for Spirit but I cannot still figure out when we'll have to start to ibernate. Another, what, 200 sols ?

Posted by: djellison Sep 5 2007, 08:03 PM

Currently it's Mid Southern Hemisphere Summer - the sun is 85.5 degrees above the horizon at noon for Spirit.

100 sols from now - that figure will be 74 degrees and it will be Early Autumn
200 sols from now - 56 degrees, Mid Autumn
300 sols from now - 50 degrees, Early Winter
400 sols from now - 60 degrees, Mid Winter
500 sols from now - 81 degrees - Early Spring.

Basically it's the 150 to 450 sol's in the future period that will be the worst of it

That's all using the mars24 applet - our resident Purveyor of Whr's might be able to do a better job

Doug

Off topic posts from after 30 October moved to new thread:
http://www.unmannedspaceflight.com/index.php?showtopic=4837

Alan