Wow, an amazing image to have captured yourself!

Thanks! I wish the dust storm had not been in the way, and I know that many others feel the same. Perhaps it will fade soon.

Hmm. Although the seasonal upward trend is similar, the pressure during this dust storm, as measured by REMS, is about 20 pascals lower than at a similar period during the last three Martian years.

Pressure (pascals) for LS 198-208:
2018 779-807

2016 798-823
2014 802-829
2012 805-830

Sources:
https://mars.nasa.gov/msl/mission/instrumen...onsensors/rems/
https://github.com/the-pudding/data/blob/ma...ars-weather.csv

I wouldn't read too much into this. The Gale crater temperature/pressure during the course of a sol is governed by the crater topography so that during the day as temperature increases atmosphere flows out of the crater reducing the air pressure while at night colder air settles into the crater from the rim. The drop in upper atmosphere temperatures and increase in lower atmosphere temperatures due to the dust storm has probably had an effect on this cycle.

The lower pressure this Mars year seems to have preceded the dust storm by several months.
For example at LS 135:

2018 727

2016 747
2014 750
2012 N/A

The 2018 LS 135 was on 02-27. Perhaps an overall lower pressure is predictive of the year in which a major dust storm is likely to occur?

According to http://cab.inta-csic.es/rems/wp-content/up...RATION_PLAN.pdf the pressure sensor is only required to be accurate to 10 Pa at beginning of life and 20 Pa at end of life (end of the primary mission, I presume.) It may be doing better than that, but I'd be reluctant to draw any conclusions from absolute pressure measurements over long time scales without taking possible instrument drift into account.

Good point! Based on your comment I took a look at when the larger pressure differential occurred.

Earth_date ls month pressure

2017-08-18 048 Month 2 881
2015-10-01 048 Month 2 901

2016-09-12 220 Month 8 859
2014-10-24 220 Month 8 862

The deficit in pressure from the previous year seems to have gradually widened over a period of about a half Martian year, and to have stayed roughly constant since then. This could be consistent with instrument drift. It will be interesting to see where it goes from here. It's a pity there is no ongoing way of calibrating the instrument.

Can radio occultation measurements from orbiters be used to measure pressure? That was how atmospheric density was measured in many other cases in the past, e.g., Voyager 1 and Titan.

The interpretation of the pressure differences above might be different if the altitude change were considered: ~225 m in the Ls 48 comparison, but only ~89 m in the Ls 220 comparison. One would expect a more than 2% drop in the first case (little residual), but <1% in the second (residual increases slightly with time between those two specific points). Given the possibility for drift, interpreting any residual variation seems sporty.

Just saw what looked like a brief downllink from Opportunity on DSN Now:

DOWN SIGNAL

SOURCE
OPPORTUNITY

TYPE
CARRIER

DATA RATE
1.10 Mb/sec

FREQUENCY

8.45 GHz

[EDIT: Now it is showing MAVEN as the source with similar data rate and frequency. Maybe it was some kind of switch-over glitch.]

You will regularly see very brief appearances of Opportunity 'locking up' briefly.

It's usually side bands from MRO, and less frequently MAVEN drifting thru the frequency we're looking at - and the receiver incorrectly locking up on it. We have to manually drop lock and then carry on looking - so briefly, it appears Opportunity is transmitting when it isn't.

https://mars.nasa.gov/mer/home/

New status report and press release about the dust storm posted at the MER home page.
Misfortune for Opportunity but an opportunity for MAVEN.

Glimmer of hope from the latest MRO MARCI Weather Report that things might start improving:

When spirit failed to restart when the spring came I was convinced by the official explanation that the electronics had been damaged by low temperatures. However it was also possible that spirit did not restart correctly because of an error in the software or hardware designed to carry out this recovery. I realize that insight has different hardware but I wonder if there has been a full end to end test of recovery from a flat battery and no sunlight using the insight reference hardware. The insight radio science experiment simply requires radio communications over more than two years to be successful. I wonder if insight would recover correctly in a similar scenario to that currently being endured by opportunity?

No idea. Probably Giang Q. Lam, Scott Billets, Timothy Norick, and Richard Warwick. "Solar Array Design For The Mars InSight Lander Mission", 14th International Energy Conversion Engineering Conference, AIAA Propulsion and Energy Forum, (AIAA 2016-4520), https://arc.aiaa.org/doi/abs/10.2514/6.2016-4520 has some information, but it's behind a paywall.

I'm not sure if a worst-case global dust storm was a credible contingency for InSight planning; I suspect not.

See "Energy management operations for the Insight solar-powered mission at Mars" https://ieeexplore.ieee.org/document/7943965/

Article is paywalled but the figures suggest that all of this analysis was done before the current dust storm, and the maximum tau value shown in the figures was about 5 IIRC.

It looks like the design team is, reasonably, planning to survive under then worst-case conditions:

"The lander and its unique suite of instruments - a 3-axis
precision seismometer and a self-drilling heat probe both
deployed with a robotic arm onto the Martian soil - have been
designed to operate and/or survive while maintaining a
margined battery-charging energy balance every sol, even
under the combined effect of worst-observed atmospheric dust
opacity (“tau”), worst-case tilt of the solar arrays and a
conservative dust accumulation rate on the solar panels that
assumes no wind cleanings dur
ing the entire mission. '

A major design challenge for dust storms could be the Mars sample return lander and fetch rover. The current working date for landing, 2026, puts the landing in the dust storm period. Both the lander and fetch rover would be solar powered. Presentations on design considerations for both highlight the need to survive the dust storm.

The lander will have a need to keep the fuel in the Mars ascent vehicle above a minimum temperature, likely creating a design challenge in the case of a major dust storm.

The presentations on the fetch rover discuss the need to survive a prolonged dust storm without including any radioisotope heating units in the rover.

As I indicated, though, that appears to have been only the worst-observed prior to the recent dust storm.

Insight will land on November 26, 2018. That is virtually simultaneous with the next southern summer solstice – November 28.

A previous monster dust storm, in 1971, began about three weeks before that southern summer solstice.

This one began about six months before southern summer solstice.

So one thing we can hope for, at minimum, is that Insight will get through nearly an entire martian year before the next dust storm would likely begin.

Is the radio science experiment seriously compromised if it completes a bit less than one martian year?

It seems like the baseline failure rate of missions to the surface of Mars is much higher than the risk Insight faces due to a dust storm, but it's a good issue to bring up. Unlike purely engineering-based risks, this one (given solar panels for power) is beyond our control. It seems like landing right at southern summer solstice is a fortuitous design (or chance circumstance), though.

Note: If Insight had launched at its originally planned date of March 2016, it would have landed in September 2016 and had approximately 18 months of operations before this dust storm. The 2018 launch date reduced the risk. (Which, in hindsight, is more than risk for the voided 2016 dates.)

Opportunity parked from sol 2795 to 2963 to conduct a 5 month mars radio science experiment. I remember at the time that it was said that extending this period would not have provided any more accurate radio science data unless opportunity parked for two full earth years. From this I presumed that insight would need to operate for at least two years to better opportunity's radio science data.

An information packed update on the dust storm in general and Opportunity in particular.
http://www.planetary.org/explore/space-top...ity-sleeps.html

"In the Dust Storm, the mighty Dust Storm, the rover sleeps tonight"

Thanks Serpens for that link. It seems hopeful that the rover may be waking up before too long.
In the early days of the MER mission, the ground ops team used to play "wake-up" songs for the rovers.
http://www.mit.edu/~jfc/MER%20Soundtrack.html
That tradition seems to have faded away after the prime mission, but given the long sleep now, it might be appropriate to revive it just once when the rover does wake, for public outreach purposes.
Possible choices (recycled from the list in the link) might be:

Oh What a Beautiful Mornin'
Soak Up the Sun
I Can See Clearly Now
Wake Up Little Susie [Oppy]
...

Good to see some tau estimates in that report, based on MARCI data:
Of course there's nothing like ground truth, but this does sound promising.

And some values from MSL:

So, at what point does it become concerning that we have not yet re-established contact with Oppy?

There has to be some point at which orbital and telescopic data would indicate tau in Meridiani is at a low enough level that, if Oppy is going to be recoverable, we would begin to expect to hear from it. My guess is that a fair number of people working on Oppy have a good idea of what this timeframe is -- or, failing a timeframe, at least at what level of clearing we ought to start reasonably expecting contact -- but as of yet, I've seen nothing, not even speculation, as to when this might occur.

Again, not so much against a date as against a tau level -- at what level of clearing do y'all think JPL begins to seriously expect to regain contact, if such will be possible?

-the other Doug

I think the article suggests tau needs to be near 2 before expectations of success rise significantly. It could be sooner (or even later), depending on cleaning events and other specifics, but that is the gap between hope and expectation. While lack of communication is always frustrating, I do not think that it becomes a specific source of concern until well into next month; maybe even later. Then, Callas described a long process of bringing the rover back to a normal mode of operations.

After the 2007 peak, communications occurred consistently after tau dropped to around 3.8, and mobility after 2.5. But the rover's mode and state of charge were in entirely different places then.

Yeah, from the report we had:

Obviously huge uncertainty in any such projections...

Despite trying as hard as I could to figure out exactly what the recovery process might look like from public information, I haven't been able to figure this out from the papers or what various project people are quoted as saying.

EDIT: I did run across this -- http://www.planetary.org/explore/space-top...mer-update.html -- which has more detail about the need for "sweep and beep" than I had previously run across.

That infers you know the solar array dust factor - which we do not.

Well, it's somewhere between 0 and 1. One could figure out based on season and a range of dust loading what the tau needed to get into "solar groovy" (1.1A of production) would be -- then it's a matter of hitting the narrow window when the rover would be responsive to commanding in that mode.

What I don't understand about solar groovy is what the battery SoC has to do with it -- is the 1.1A after whatever the battery charging is using? What happens if the battery just refuses to charge?

IIRC once the clock is lost (which is a likely event) the BCB needs at least a 2A current from the array and 27V on the batteries before attempting to beep.

Paolo

The sporadic nature of the Martian dust storms reminds me of the sporadic occurrences of wildfires (which are currently raging here in California). Apologies if this seems like a far-out idea, but I'm wondering if combustion ever occurs on Mars and whether it might be related in some way to the dust storms.

The regolith is now known to contain organics and perchlorate, which may build up over time. This might conceivably form a combustable mixture in some places. Given the frigid Martian temperatures, combustion would be rare but perhaps a meteor strike could trigger ignition? Combustion could raise dust (and smoke) into the atmosphere which might be enough to trigger a positive-feedback process. Such events would tend to be self-limiting, though, given the depletion of the consumable resource.

Of course, this suggestion could easily be falsified by Maven observations, which presumably could detect the products of combustion.

My chemistry is not so hot (pun intended), but combustion doesn't it require an oxidizer?

Paolo

https://en.wikipedia.org/wiki/Perchlorate

The perchlorate serves as the oxidizer.

Open question as to whether deposits of organics of sufficient mass in close proximity to large concentrations of perchlorates exist anywhere on Mars for this to occur to say nothing of the probability of an ignition event, but I gotta rate such a confluence of favorable circumstances as unlikely to the point of 'ain't gonna happen' (yes, that's a technical term ).

Moving on...

Thanks, guys. The technical discussions thus far available had not been much help for me to understand what the thresholds are for a MER re-animation after a major dust storm event. I've got a much better idea now. This is exactly the discussion I was hoping to see, again much thanks.

And yes, we don't know the dust loading, but as Mike pointed out, it's got to be between 0 and 1, thus providing a range on a graph that must, when added to the tau range and the minimum charge required for the rover to start up again, define the conditions required to get to a re-activation of Oppy.

In my mind's eye, there is a graph, sort of a Venn diagram, of those three sets -- tau, dust loading and resultant power -- and the area where they overlap is the area in which we can expect a successful re-activation. And it would surprise me no end if such a graph does not exist for all you JPL types to see. I was just trying to get some insight on what the ranges are in each of the major categories, and how each sort of generally plots against time, is all.

But, yeah, planetary exploration via Venn diagramming...


p.s. -- Even with all the times lately (and yet upcoming) I have had to undergo surgeries, and get another few million brain cells whacked by the anesthesia, I am still swift enough to understand that there is not a magic date on a calendar beyond which the situation goes from "we're confident and optimistic" of recovery to "let's declare Oppy finally dead and have a wake for her". Like I say, I was just trying to get the shape of that Venn diagram I mentioned straight in my head. Again, thanks!

Power models are run based on presumed battery voltage ( all we know is it is < power fault voltage ) dust loading (which we don't know with any accuracy ), presumed Tau ( which we don't know either - we can sort of infer from MSL, and MARCI when MER gets occasional updates from that team ) - but they're little more than educated guesses.

You could run the numbers and argue the vehicle should have woken up last week, or not until October. It's almost as bad as running the Drake Equation. You put in the numbers to get the answer your want.

Moreover - tau varies, a lot, during a storm decay. We might see enough power on the arrays on one day to start charging the battery back up but not hear anything...but then have three days of worse conditions. There are also fault recoveries where we might be listening at the wrong time, etc etc etc.

In short - tomorrow is better than today, generally speaking. The story only really gets worse when next winter arrives - many, many months from now.

Thanks much, Doug!

https://mars.nasa.gov/msl/mission/instrumen...onsensors/rems/

Some new readings from REMS. The pressure now seems to be running about 30 pascals lower than the average for previous Mars years.
Perhaps due to a further increase in altitude by Curiosity?

Something to do with the dust storm, perhaps? How much higher has the rover climbed since landing? I recall seeing a 'side chart' detailing this somewhere on the board a while back...

I believe the landing elevation was in the order of -4501 meters. The current elevation (reached on sol 2132) is shown as -4170 meters on the JPL traverse map. However the rover drove downslope from its higher elevation on the ridge to reach this drill target. So are you looking for the max elevation or current elevation.

The month 11 weather report attributes the drop in pressure compared to last year to Curiosity's increased elevation and also notes the effect on pressure of the reduced temperature range due to the dust storm.

Is anything known about the after-effects of a major dust storm on the global distribution of dust? For example, would it tend to move dust from lower elevations to higher elevations or vice versa?

It's been observed since before people knew what they were looking at that summer moves dust from darker, warmer landscapes, clearing them of dust, lowering their albedo, and thus raising the local daytime temperature some more. On an aggregate level, this moves dust from the summer tropics to the other hemisphere. Overall, there is presumably a long-term equilibrium over millennia.

If you look at Mars' albedo on a very coarse level, there is a dark belt around 30° south. This happens to be the sub solar latitude at a time near perihelion and martian southern summer solstice, thus the hottest latitude on Mars.

All of this is what led Percival Lowell, et al, to conclude that dark vegetation was spreading in local summer. What they were actually seeing was dark martian regolith being cleared of dust.

Don't be misled by reports floating around now that Opportunity has been communicating. JPL has confirmed that this is not correct, and it is thought to be a misinterpretation of the DSN activity graphics.

Phil

Yeah - someone saw Opportunity in lock on eyes.nasa.gov/dsn and told the world the spacecraft was clearly alive, talking to us a 6 megabits per second.

This is the bulk of what I said to correct him........



Someone still wasn't sure....so....

Click to view attachment
In this screen capture from the NASA Mars report
https://www.youtube.com/watch?v=IJtjJSHsm9c
it appears that the global dust has diminished considerably.
In the weekly weather report
https://www.msss.com/msss_images/latest_weather.html
the area at the location of the rovers may be transmitting more light, although not yet clear.

2nd last paragraph of this update says Tau is still around 2.1 to 2.5, still too high for charging to start.

I wonder what HiRISE could see at Perseverance Valley by this point... is it still too opaque to make out the rover from orbit?

Interesting thought. I wonder how much dust deposition there's been; might be a bit difficult to pick her out from the surroundings at first.

I can see from my own photos that the dust storm appears to be essentially done in the vicinity of Syrtis Major. After months of Mars looking weird, it's now totally or almost totally normal. How clear Opportunity's solar panels are (about 90° west of there) is anybody's guess.