Expect a quiet few sols - http://www.lpl.arizona.edu/~lemmon/mars-tau-b.html
SOL TAU
5097 0.65
5098 0.64
5099 0.67
5100 0.64
5101 0.60
5102 0.60
5103 0.61
5104 1.55
5105 ****
5106 2.12

Breaking news: As Mars nears one of its closest perihelion passes, a large dust storm has developed. Per the press release, the storm now covers a surface area the size of North America. It may possibly grow into a global storm as has happened during previous close perihelion years (notably 1971, which coincided with Mariner 9's arrival).

Needless to say, this will produce highly challenging conditions for Oppy, and the mission team is making survival preparations. Science operations have been suspended at this time.

We wish the team the very best of luck, and GO OPPORTUNITY!!!!!

Oh god.

Some details of the storm activity at the MRO MARCI Weekly Weather Reports site. That's only updated weekly, on Wednesdays.

Good luck to Opportunity and to the very talented team that has brought her through obstacle after obstacle after all these wonderful and fascinating years. She will prevail with the Sun gleaming off her dust-free camera lenses and solar cells after this passes. GO OPPY!!

Given the length of the mission, it was only a matter of time until another dust storm showed up; hopefully it won't be global or very long lasting!

Once the dust storm per se abates, there may be a period while dust settles out of the atmosphere. I wonder if there might be some advantage at that point to positioning the rover on a slope so that it minimizes the catchment area that is presented to the falling dust. If this conflicts with maximizing the sun exposure of the solar panels, perhaps it could be done at night.

"I wonder if there might be some advantage at that point to positioning the rover on a slope"

The rover is already on about as steep a slope as it can easily manage. But pondering the geometry, to reduce the projected area of the panel to 50% you would need a slope of 60 degrees, completely impossible. The allowable slopes are only going to cut dust deposition by a small amount. We'll have to rely on wind gusts.

Phil

When you have skies this dusty - the single best strategy is to be flat. You're getting your power from the diffuse glow of the whole sky.....anything other than flat hurts you.

Also, with panels flat, a gust of wind from any direction will blow off dust.

Moreover - it's not dust 'fall' that hits the arrays - it's just blowing around and sometimes you get some. Tilting at a large angle may actually put your arrays facing upwind and cause more harm than good.

Will Opportunity get a chance to send back images from the surface during the dust storm?

Other than taking occasional tau measurements of the sun - no - there simply is not enough power to do so.

If you look at the MER raw image page and PanCam tracking database - you'll see the only imaging attempted since Sol 2107 has been tau measurements of one sort or another.

I wonder how much tilt you need to shake some dust off by jiggling around a bit. Anything worth trying there?

The sort of slope that represents a threat to vehicle safety can cause some kinds of coarse dust, bordering on sand, to rattle down the rover deck.

This is all academic - we don't know how long this storm will last, nor what state the vehicle will be in when it ends. We may find we come out of it with hundreds of watt hour to burn.

Remember - dust on the arrays is not the problem right now. It's dust in the atmosphere. A brand new rover with clean arrays would also be in trouble right now. We went into this with a pretty clean rover. A dust factor of 0.772 ( see https://mars.jpl.nasa.gov/mer/mission/statu...tml#opportunity ) is remarkably clean.

Dust collects on upwind slopes, not downwind.

Sure, my question was not about managing the situation right now, so academic in that sense. That's good information on the sandy stuff sliding on dangerous slopes, thanks. Just one thing I'd like to add: the solar panels however they are supported must have some some natural vibration frequencies. If it were possible to drive those natural oscillations the amplitude might be enhanced to the point where more dust slides.

Is it still true that the prevailing wind is upslope?

They wobble - yes - and that's caused sand to slide down them driving on dangerously steep slopes in the past.

That's a rather simplified view of what really occurs

Papers like this : https://onlinelibrary.wiley.com/doi/pdf/10.1002/esp.1272 : go into it in more detail.

Moreover - the rover itself presents a topographic feature to the oncoming wind, whatever angle it comes from.

Thanks. I thought I saw an image taken by one of the MER rovers during a dust storm.

Oppy as well as Spirit did take some images of the ground to monitor pebble movement and images of the horizon during the 07 global storm when power conditions allowed it.

Yep. Spirit provided a sequence of images that provided a short movie of dust ripples in motion, but I think this was taken towards the end of the storm as the intensity of the dust diminished.

This mosaic is from Opportunity
https://www.nasa.gov/images/content/182691m...er-20070719.jpg
during the 2007 storm.

They were able to execute simple Pancam observations briefly during that storm. However - even if the tau were the same now, Opportunity would be in worse shape for all sorts of reasons (11 year older batteries, on a slope, it's not high summer ).

However - the tau is a lot LOT worse right now. We've seen both record high tau's, and record low power. The vehicle is facing conditions we just have no experience with.

I am curious if the full frame wide range tau images that have been coming down shows any trace of the solar disk in the original data products, Doug? And if so, can a current estimated Tau be worked out from them, heard anything? Mark's site was last updated on 5106 when the last visible solar disk images were taken.

Hoping to see some new values added to that site soon. The combination of data from which tau may not be automatically extracted and a newsworthy event may require some permission to restart the updates.

The Tau is about double the worst experienced by Opportunity during the last storm. With the current orientation what is the correlation between tau and Whr generated? Since the attenuation of sunlight through the atmosphere is essentially exp(-tau) the observed light intensity with tau around 10.8 must be negligible.

I suppose since the news is here, it is on the plot here.

I did a very simple 2-stream model, and you can approximate total insolation (proportional to array W-hrs/sol) as varying with exp(-tau*gamma), where gamma is 0.35-0.40 or so. If you compare two sols, that's exp(-delta_tau*gamma). A lot of the extinction goes into sky light, but total light is still much reduced. At these taus, tilt is a small perturbation, I'd guess. (A chunk of sky is blocked, but that chunk is the source of a small fraction of light, and the tilt hasn't changed.)

I guess there isn't much data from the ground during dust storms to say very accurately how much reduced the total light is. Technically the tau itself tells you how much darker the sun has become, but as Deimos says some of that will be scattered to the ground via the sky.

Anyway of course we don't need to do full scattering calculations, since what really matters is array power, which is known (if not publicly).

I just can't believe how fast the tau increased. Over the years it oscillated just below 1, and now within 8 sols it increased by 18 times.

Has Opportunity ever been in a low-power fault state? I'm thinking not.

As far as I know, Spirit went into this state on sol 2210 and never came out, although this is supposed to be recoverable.

I guess Opportunity would be better placed to come out of a low power fault state. Spirit had to try and survive the depths of winter. With the dust storm maximum temperatures will be cool but minimum temperatures will be higher than normal for this time of year and the radioisotope heaters may be able to cope.

https://mars.nasa.gov/mer/newsroom/pressrel.../20040526a.html

Is it cold enough to require "Deep Sleep" mode to keep the "stuck-on" heater from wasting energy? (I guess we don't have to worry about the Mini-TES any more.)

Does the loss of flash memory affect the hazard of a low-battery state?

It's apparently not as bad over Curiosity's landing site, but the air is noticeably dusty.
Sol 2077 MastCam.

I'm not sure that the specific failure mode that got Spirit has ever really been identified. The presumption was that it was related to cold, but it would surprise me a little if there was anything about MER that could be rendered non-functional by a few deep thermal cycles. (Well, maybe the batteries, but the system would still work in the daytime.)

Hopefully there isn't some inherent flaw in the low power fault state, or better yet, that it never gets entered.

NASA will host a media teleconference at 10:30 a.m. PDT (1:30 p.m. EDT) Wednesday, June 13, to discuss a massive Martian dust storm affecting operations of the agency's Opportunity rover and what scientists can learn from the various missions studying this unprecedented event. More at link:

https://www.jpl.nasa.gov/news/news.php?feature=7158

Now that we have equipment on Mars, should global dust storms get names like Earth hurricanes or typhoons?
Guess the 2007 storm would be "Ashes" and this would be "Bowie"?

Can only imagine what it's like at Oppy.

Has there been any further communication from Opportunity since Sunday morning?

There will be a telecon tomorrow (Wednesday June 13, 2018) at 10:30am PDT

https://www.jpl.nasa.gov/news/news.php?feature=7158

Paolo

I don't know. I happened to notice a DSN track on DSN Now this morning but nothing was received while I was watching.

The JPL news story on the dust storm was updated this evening to say that the rover failed to check in today and is likely in low-power fault mode.

https://www.jpl.nasa.gov/news/news.php?feature=7155

Bummer. Per https://trs.jpl.nasa.gov/handle/2014/37750 (assuming there are no changes to the fault response), if it gets enough power to boot back up, comm is limited to one LGA DTE per day at 11 LST, unless the ops team can get commands in to alter this behavior and enable UHF comm. I'm sure this will all be described tomorrow.

Thanks for that link. I guess all that can be done now is sit back, cross all available fingers and hope that this amazing feat of engineering design can astound us one more time.

On Si=ol 4311 we "drove" uphill at 32 degrees and excited the vehicle with quite large values of vibration and very little dust was moved. We tried on Spirit as well back on a slope (also at 30deg) before leaving the north side of Home Plate and there was no measurable effect on dust factor. I think one has to consider we are talking DUST, not sand.

Paolo

Are the solar panels able to raise up? I say this when MER traveled thru the space, the solar panels was inside in compact mode before it landed.
During the process of closing (raising) and opening (lowering) solar panels might shake due to the motor vibration or also due to the slope, some
dust will slip down.

No, those were a one-time use, though good thinking outside the box!

Telecon starting now....

People should think of their TV screen. It has dust on it. It's vertical. The dust just sits there.

The news conference was upbeat. They expect the rover to survive based on observations so far. Good news is this is happening during the summer so battery temps aren't as much of a concern. (I was unaware there were warming plutonium sources inside the battery compartments). Very little power is required to run the onboard clock and even if it stops, the rover can awake again from new solar input and go into a search mode to contact Earth. Fascinating. Such amazing engineering and staff.

The wind blows the panels clean from time to time.