Spirit cleaner? Options

[alan]

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...I4P0165L0M1.JPG
http://207.7.139.5/mars/spirit/navcam/2007...00P1914L0M1.JPG

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

[akuo]

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.

[jmjawors]

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.

[centsworth_II]

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

[fredk]

Yes! We're above 600 Whr!!

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

[dvandorn]

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

[mhoward]

Yes! We're above 600 Whr!!

The news we've all been waiting for!

[dvandorn]

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

-the other Doug

[slinted]

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:

[CosmicRocker]

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.

[Jeff7]

Most excellent news.

[ElkGroveDan]

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

[djellison]

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

Attached thumbnail(s)

 

[akuo]

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!

[helvick]

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.

[centsworth_II]

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

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?

[elakdawalla]

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

[alan]

This is the best I could get out of Autostitch

[dvandorn]

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

[ElkGroveDan]

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?

[Tom Tamlyn]

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

[climber]

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

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.

[edstrick]

"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!

[helvick]

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.

[CosmicRocker]

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?

[RobertEB]

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.

[Tom Tamlyn]

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

[centsworth_II]

...closing the solar panels...

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.

[RobertEB]

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.

[Guest_Analyst_*]

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.

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

[fredk]

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.

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

[dilo]

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!

[djellison]

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

[alan]

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

[jaredGalen]

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

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

[dvandorn]

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

[BrianL]

Depending on the rate of deposition vs. the rate of cleaning during such a storm

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

[David]

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.

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?

[helvick]

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:

CODE

Tau       Whr/Sol      Beam
0.9        730         38.0%
1.5        609         19.2%
2          529         12.5%
4          314          1.8%
6          198          0.3%

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.

[fredk]

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.

[djellison]

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

[helvick]

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.ntr..._1994010257.pdf

[Tom Tamlyn]

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

[dvandorn]

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

[fredk]

Spirit's Solar Power Levels Continue to Rise
Another cleaning has occured. Power has risen to 738 watt-hours!!

[Jeff7]

Most excellent indeed.


The new Mars forum question:

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

[edstrick]

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.

[helvick]

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?

[Guest_Analyst_*]

Spirit's Solar Power Levels Continue to Rise
Another cleaning has occured. Power has risen to 738 watt-hours!!

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

Analyst

[helvick]

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).

[helvick]

Tau measurements estimating the amount of dust in the atmosphere rose from 0.69 to 0.75. (Perfectly clean solar arrays would have a dust factor of 1.0, so the larger the dust factor, the cleaner the arrays.) Electrical energy rose to 738 watt-hours.

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

[dvandorn]

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).

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

[centsworth_II]

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.

[djellison]

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

[centsworth_II]

They didnt want to do a rush job last time...

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?

[djellison]

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

[BrianL]

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

Brian

[djellison]

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.

[fredk]

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?

[centsworth_II]

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.

[centsworth_II]

But fortunately getting to a steeper slope may not mean having to drive uphill.

Right!

[helvick]

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.

[centsworth_II]

... the above numbers are really only good for the weeks around mid winter.

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

[brellis]

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

[djellison]

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

[Tom Tamlyn]

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

[brellis]

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

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

[alan]

Cleaned Again: Spirit Self Portrait

http://marswatch.astro.cornell.edu/pancam_...ent/adeck3.html

[Nix]

woaw.. she looks good!

Nico

[Shaka]

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

[kenny]

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

[Guest_Oersted_*]

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...

[CosmicRocker]

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.

[fredk]

From the latest Planetary Society report, this description of the sol 1224 cleaning event:

"This [dust-cleaning event] was interesting, different from cleaning events we've had in the past," Squyres said... . "In the past, we've had cleaning events that took place when we were on a summit or a ridgecrest and in the past they have sometimes occurred at night. The rover will shut down in the afternoon with dirty solar panels and wake up in the morning with clean solar panels and we have no idea exactly when it happened. In this particular instance, the rover was awake and busy and active when the event happened so we can pinpoint the timing of it. It happened at 1:20 pm in the afternoon local solar time. Of course, we are now down on a low spot, not up on a ridgecrest of anything. So our speculation –- this is pure speculation at this point – but our speculation is that we took a direct hit from a dust devil. We don't know that. But we are in place where dust devils happen and it's prime time for dust devil activity, the time of day when dust devils seem to be most active."

[Shaka]

Yes, only a devil would tidy up so haphazardly.

[TheChemist]

Looks like some guys will finally get actual data to verify their simulations

[alan]

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

[hortonheardawho]

sol 1204 - 1244 L2 comparison of Husband Hill:

[Floyd]

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

[djellison]

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

[alan]

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

[hortonheardawho]

Ah, indeed:



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?

[fredk]

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 this L7 frame. That foreground horizon is about the same distance in this frame, 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?

[Pertinax]

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

[PDP8E]

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

[climber]

From the latest Planetary Society report, this description of the sol 1224 cleaning event:

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 ?

[djellison]

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

[climber]

Yes - cleaning is usually thought to be due to high winds
Dust storms are thought to cause high winds
Doug

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?

[Stu]

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...

[Guest_Oersted_*]

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

[hortonheardawho]

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


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...

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.

[Stu]

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!

[Ant103]

New pics on the exploratorium for Spirit

Look at the panel :
http://qt.exploratorium.edu/mars/spirit/na...CMP1665L0M1.JPG
It seem to be cleaned, isn't it?

[alan]

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

Spirit's forward hazcams weren't so lucky

http://qt.exploratorium.edu/mars/spirit/fo...CMP1214R0M1.JPG

[monty python]

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

[slinted]

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:

[alan]

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.

[djellison]

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

Doug

[Stephen]

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

Spirit's forward hazcams weren't so lucky

http://qt.exploratorium.edu/mars/spirit/fo...CMP1214R0M1.JPG

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

[djellison]

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