Yes.... but what goes up must come down. All that dust in the upper atmosphere has to settle out at some point..... and those beautiful solar panels make a nice target....... just hope there is a balance between dust deposition and wind cleaning events....

Worried....... stay warm little rovers.... hold on.............. if I could I would gently blow your petals clean...

Craig

OK - doing a total inline quote is one thing - doing it with your own post is madness!
Pointless quote removed! - Doug


And shine a light on your petals!!!!!!!

Craig

Yes, whatever goes up must come down, but thanks to the winds it also travels sideways. I guess it's kind of a crap shoot. As the forces blowing dust around this planet run out of energy, let us hope that most of the entrained dust falls somewhere else. Everyone, cross your fingers.

another sols info on Marks page.

Thanks for posting this, but could you provide the URL link for these?

THX.

Carrick

http://www.lpl.arizona.edu/~lemmon/mer_dd.html
(The values are in the text at the top of the page.)

Let´s hope for this descending trend in the tau values.
Meanwhile, Opportunity´s imaging operations are limited to tau measurements only since sol 1226. Same is expected/planned for tosol (1229) and tomorrow.

The early trend is in the hoped-for direction, but Dr. Lemmon's page still has no new tau values as I go to sleep tonight.


We don't have any imagery from sol 1229.

It does not appear that sol 1230 will be very active.


Sol 1231 is not a high energy consumption day, either.


I am still optimistic that it is getting better for our rovers.

2.9. So am I

Ignore the last Opportunity point - that's my guess, not an actual value.

I THINK...(well, guess) that we're closer to the 400 whr level rather than the 255 whr level now.

Doug

Out of curiosity, to reach Tau levels as we saw here (e.g. 4.0) would it typically take a storm to throw it up?

As such, would there be globally increased wind levels? Or can the storm be localised and kick the dust up into the higher atmosphere, leaving regions further from the storm with normal winds (virtually none) but high Tau? I don't know how low atmospheric pressure affects all that.

While high Tau is bad for solar junkies like Oppy and Spirit, will these events have helped glean a better understanding of mass air movement on Mars? What will they be trying to learn from the past few weeks?

Sorry for all the questions, guess I'm just thinking out loud....

During Monday's Phoenix Mission press conference, Doug McCuistion, NASA's Mars Exploration Program manager, gave a brief but upbeat report on Opportunity's ability to survive the storm. I thought I also heard him say that Opportunity could function at a power level of about 100 watts. (It appeared later on that at least one reporter interpreted the 100 watts comment as referring to Phoenix, but I recall it as relating to the rovers).

That's a lot lower than the approximately 270-80 watt figure that's been discussed here as the rover's survival threshold. I assume that a good deal of the difference is represented by the fact that less power (no power?) is needed for keeping the electronics warm during the summer season.

Aside from heating, does anyone know what functions require power (and how much) for minimum survival? Does the rover draw no power at all during Deep Sleep?

TTT

Edit to fix typo.

He did say that. But it's more like "stay alive" than "function".
I think the only thing Opportunity would be doing at that power
level would be recharging. I don't know about heating. Has
deep sleep been used during the day? I envision it as a
deep sleep/recharge situation.

To cut down power consumption, they would also need to reduce communication windows.

Emily has posted a comprehensive discussion on her blog, with a full transcript of McCuistion's comments.

Most intriguing was this, which I had forgotten: "We have the ability to charge the batteries below 100 Watts. We can do imaging even below 100 Watts. So we can select the instruments we want; we don't communicate with the orbiters as frequently."

Emily has also promised to try to obtain more information.

TTT

Emily, could you also ask (or anyone else) how the storm affects the surface day/night temperatures ?

jv

I've been looking for images of the magnets on the rover. I found a few; but I wish I could find a whole lot more.

These are the most recent images downloaded in order.

June 27th, 2007

http://qt.exploratorium.edu/mars/opportuni...R9P2976M2M1.JPG

July 1st, 2007

http://qt.exploratorium.edu/mars/opportuni...R9P2976M2M1.JPG

July 3rd, 2007

http://qt.exploratorium.edu/mars/opportuni...R9P2936M2M1.JPG

July 9th, 2007

http://qt.exploratorium.edu/mars/opportuni...R9P2936M2M1.JPG

As you can see, the wind is blowing some of the magnetic particles off of the magnets. I think that is an indicator of just how strong some of these winds must be.

The first two are both from Sol 1217 and the last two are the same picture, from sol 1223.
So there is no evidence for more than one gust.

Yup - raw images 101. The date something appears at the Exploratorium has little relation to when it was actually taken. The file name shows you when it was taken

1M236222506EFF85R9P2976M2M1

That's the time tag in red.



Doug

jaywee,

Helvick, the forum expert on Martian solar power, briefly discussed the effect of dust on surface temperature earlier in this thread (post #20, responding to post # 15).

Of course it would also be great to hear what the Mars weather scientists are learning and expect to learn about this storm from the instruments in orbit.

TTT

I wasn't suggesting evidence for any more that one major gust. Actually we don't know whether it was just one gust...just one time interval when the change occurred. My point was that it was strong enough to clean the magnets significantly.

BTW the red tag continues to confuse me. They just look like a lot of number to me.

http://midnightmarsbrowser.blogspot.com/

Get it.

Be confused no more.



Doug

I just noticed this Aviation Week Article dated July 8th (Rover Ready for Dangerous Descent After Dust Storm) It seems to have a little new information about the dust storm and operations planned for inside the crater.

Hi guys, I went to the Mars meeting at Caltech today and planned to get some answers but had to leave because I wasn't feeling well. I did catch Ray Arvidson before I left and asked him about the 100-Watt number and he said that was an error. A woman with him said she thought the number was more like 280 or 290.

--Emily

Hi all

A few times without posting because I've broken my wifi pcmcia card (thanks to gravity who have made fallen my laptop ). The problem is now solve.

I learned that a dust storm hit our rovers.... And Olivier made us a little visit

So, a picture I've made showing the inversion phenomena through the sky during a dust storm :


And here, a color panorama of Victoria crater during the storm :


In expecting that the storm will not during a lot of time

It's a pleasure to read you at new

This site on the MER homepage explains the whole image code.

That 255 whr figure for Sol 1225 is bugging me (Sorry Astr0 - feel free to object right back )

I calculate that at a Tau of 4.1 on Sol 1225 for Opportunity she should have generated around 310Whr.

All of the other numbers that I've seen recently indicate that the insolation model I'm using underestimates the real values by 10% or so ( e.g. on sol 1221 @ Tau=3.3 the MER team have published a value of 402 Whr when I estimated about 360 Whr ). That would make me expect a real value of about 340 Whr if the Tau value of 4.1 is correct. Furthermore I really suspect that there was at least one small (5% or so) cleaning event sometime between Sol 1211 and 1220 which would put the number closer to 355Whr.

The most likely reason for this is that the diffuse Insolation model I'm using becomes increasingly unreliable as Tau rises past ~3 but it is also possible that the 255 Whr number isn't accurate. I'm also very surprised at Opportunity being able to function at all at that level, my understanding all along has been that 270-280Whr is extremely marginal for her given her stuck heater.

Very much looking forward to published numbers from the team.

The code is explained here.

Edit: sorry didn't see Tman's post as was reading the previous page.

Well, we had that report that began this thread that the direct sun was attenuated by "nearly 99%" (tau = 4.6), with power at 280 Whr. The report was dated the 5th (sol 1225), though the sol is not mentioned in the article. Does that fit your model better?

The more recent data show a peak at 4.1, so 4.6 seems to have been an error. I suppose at times like this with everyone wanting tau values, numbers get out that aren't very accurate. Let's hope the clearing trend continues!

Is it possible that the Tau reading is just a single point on a line, ie the Tau could be 4.6 now, but could be lower or higher before and after that reading. Tau comes from looking at the sun, right? So power produced could be slightly off from what you expect because the dust isn't consistent either across the sky, or from morning to evening.

high dust opacity drops daytime temperatures, but raises nighttime temperatures.

Local dust storms, if strong, show strongly convecting or at least dynamically churning clouds, often with some mixed-in condensation clouds, as seen from orbit. They can probably be quite opaque, but then the dust spreads out and disperses, like the storm that happened shortly before Beagle and MER's arrived.

Globe-encercling storms have been observed from orbit in development phase 3 times (2 viking orbiter storms and the 2001 storm), and once in the decay phase (the greatest of all, the 1971 global storm: Mariner 9.) Storm heating probably has a massive "ripple" effect on the adjacent atmosphere, as well as strongly boosting global atmospheric thermally-driven tidal oscillations, and can probably cause unusually strong winds even in non-storm-dust affected areas before the dust arrives. Areas near an active storm may plausibly have such strong induced winds that there is strong local dust scouring and lifting, causing a propagation of the main storm, starting solar heating of the newly raised dust in a sort of chain-reaction effect.

We just don't really understand the meteorology of storms and their growth. Vikings got some good photography at intervals, as well as infrared thermal mapper data. The 2001 storm was before Odyssey's arrival, I think but had good coverage by MGS's wide angle cameras and the thermal infrared spectrometer. With the wide angle cam on recon orbiter and the climate sounder, we're getting our first meteorology instrument look at a big storm :-) I hope to hell the've switched the instrument back into scanning mode for the storm.

I would be strongly suspicious of any answer other than 'absolutely'.

The dust in the atmosphere certainly varies on short time scales -- they do on earth. Also, as you noted the extinction of sunlight would be greater for lower sun angles than higher for any given tau, as the effective optical depth increases with a lower sun (sun having to shine though a greater volume of air & dust). I have wondered myself how for a constant tau the sky appearance (including of course scattered light) would vary.

FWIW: http://marswatch.astro.cornell.edu/Bell_etal_SkyColor_06.pdf

-- Pertinax

Thanks for the input folks.
The MER team's Tau values into account the solar zenith angle and the resulting increase in air mass as do my calculations for beam insolation. You can see this in the published Tau charts - the air mass numbers and DN's vary as they should with the changes in the local true solar time of the Pancam shots the readings are based on and the resulting Tau values are pretty consistent throughout each sol (on the occassions that multiple readings are taken)

However even though they are consistent there is definitely a daily cycle - Tau (generally) increases slightly over the course of a normal sol and then clears up slightly again overnight. Whether this cycle is more or less pronounced during a storm I can't say but for the vast majority of the year the variation is <0.1 over the course of each sol. To explain the variation I'm puzzled by we would need a variation of about 2.0 for about half the sol.

It is probable that part of the explanation is that very short time scale events (passing higher density dust flurries for example) are causing significant variations in Tau during the day.

For fun, a question that I can probably dig for an answer for if there is not a quick one available here.....

Question: Is there engineering data available from the rovers (in the PDS I would presume) which reports the output from the solar arrays? If so, what is the temporal resolution (and averaging period if any) of the data?

It would be fascinating data if available in decent resolution.


-- Pertinax

I was wondering if we have, here on Earth, the equivalent of Marsian's dust storms?
For exemple, dusts coming from deserts that goes very high in our atmosphere where the pressure could be comparable to what it is on Mars?

I've been saying that for years.

I don't think we'll see it any time soon unfortunately. It's engineering data that doesn't directly feed into any science data (as far as I know) and since some of the engineering data skirts into ITAR terrain releasing any of it requires that lawyers clear it first. That's just asking too much for data that is only of marginal interest at this stage in the mission. It would be great if someone used the data as part of a paper (say on short time scale variations in atmospheric opacity) and got it published that way,

The temporal resolution was good enough for the team to be able to specify that Spirit's last major cleaning event happened at 13:20 local time (IIRC) so I think it's at least possible to get it down to 10 minute intervals.

Desert dust certainly can spread quite far. For example a fair amount of the soil on Bermuda is very fine saharan dust accumulated over hundreds of thousands of years. However terran "weather" in almost all forms very largely happens in the troposphere. For example despite the vast amount of salt spray created continuously over the oceans essentially nothing gets into the stratosphere (otherwise the sky at twilight would be yellow from the Na and the ozone layer would be destroyed by the Cl).

About the only exceptions is material from volcanic eruptions and large impacts which gets injected into the stratosphere with consequent climate effects extending over years (dust in the troposhere is washed out by rain fairly quickly).

Saharan dust landing on cars in the UK isn't uncommon - I remeber two distinct occurances of that in the past decade or so.
Meanwhile - updated to 1230/1250 actual figures

Massive kudos to Mark for putting these on line so quickly.

The Sirocco:

Some nice pics here of the dust blowing from the Sahara up towards Europe.

http://en.wikipedia.org/wiki/Sirocco

Infact -thinking about it - I remember finding comedy in the fact that a Sirocco was dumping sand on my mums VW Sirocco.

Doug

Did any DD cleaned it up?

A similar phenomenon we have here is "muddy rain"; it isn't really muddy, of course, but it is rich enough in dust that was lofted into the atmosphere in arid West Texas and deposited here to leave a significant film on one's car.

'helvick' said that figure is "bugging me".

Hi Helvick,
That number came straight from someone on the MER team.
I'm sure that there's room for error though.
Astro0

The latest navcam shows several changes in the tracks - the wind's been a-howlin' at Meridiani. And the shadows are much stronger now! (These views are less than half an hour apart local time.)

Sol 1224.
Sol 1231.

Thanks for the confirmation Astr0. I'm going to have to hope that this means that Tau was varying fairly dramatically that day. Otherwise I might have to accept I've been wrong. Oh The Shame!

According to this report on space.com the dust storm is still spreading.

http://www.space.com/scienceastronomy/070711_mars_dust.html
and
http://themis.asu.edu/dustmaps/

The enormous dust storm raging across Mars' southern half has begun to creep into the northern hemisphere as well, new satellite images reveal.

"This storm isn't as big or severe as the one in 2001," Bandfield said. "THEMIS and other orbiters can still see the surface, despite the continuing dust activity."

It's uncertain how long the current storm will last, but it probably won't disappear as quickly as it began. "Mars will remain dusty for at least a couple more months," Bandfield predicts.

Sounds like the rovers will remain power-starved for a Long time.

Good eyes fredk. I'm going to make an animation to show this more evident

The Themis link is very good : hop! direct favourite

Edit : gif is finish.

Click to view attachment

The is little material disturbing, particulary just behind the low-gain antenna.

Especially long if they read the scale bars in reverse.
What's wrong with this picture? space.com figure

It occurs to me after comments in the Spirit thread that even though the local times are very similar in the two navcams I posted above, the tau has dropped from around 4 to around 3 so the lighting is less diffuse now. That should account for some of the changes visible in the tracks, but not all.

From Lemmon's dust devil page, Oppy is stable at tau = 2.9 as of sol 1231, but Spirit has climbed in the past few sols to tau = 2.8 on sol 1252, which is the highest Spirit has ever been.

I get the sense this could linger for some time. The fat lady has not yet sung.