Dust Storm Options

[helvick]

Bill:

We're talking End Of Mission!

Bob Shaw

We're only talking end of mission if things get really bad and stay that way. Oppy's been generating somewhere in the 600Watt/hours per day range lately. An extended period where Tau is around 2 would reduce that by 20-30% which would make things more difficult but wouldn't kill her. A really major event (Tau~ 5) would bring that down to around 240 Watt/hours which is below the level that I think she needs to survive for an extended period. Even at that level though I think there would be enough juice to wake up and blip out a "Hello I'm still more or less alive" direct to earth message.

To give you an idea what a major planetwide storm would do - the second 1997 storm had Tau > 4 for approximately 36 Sols (based on a model from Viking data) and Tau >2 for about 80 sols. It's important to remember that the general consensus is that we're too late in the season for a storm like that.

The

[Nirgal]

We're only talking end of mission if things get really bad and stay that way. Oppy's been generating somewhere in the 600Watt/hours per day range lately. An extended period where Tau is around 2 would reduce that by 20-30% which would make things more difficult but wouldn't kill her. A really major event (Tau~ 5) would bring that down to around 240 Watt/hours which is below the level that I think she needs to survive for an extended period. Even at that level though I think there would be enough juice to wake up and blip out a "Hello I'm still more or less alive" direct to earth message.

To give you an idea what a major planetwide storm would do - the second 1997 storm had Tau > 4 for approximately 36 Sols (based on a model from Viking data) and Tau >2 for about 80 sols. It's important to remember that the general consensus is that we're too late in the season for a storm like that.

The

ok, I'm confident that the Rover could survive during the duration of most dust storms but the question is: how does the storm affect the accumulation on the solar panels *after* the storm ?

I'm afraid that the wind itself ceases long before the majority of the dust (very light particles !) eventually falls out of the atmosphere:

this could be bad because all the dust that had been kicked high up into the atmosphere would now slowly trickle out of the air like snow-flakes on a windless winter day, accumulating on the solar panels without the wind necessary to blow it away ...

Question for the experts (hevlick ?): how did the dust accumulation develop after past dust storms that Oppy observed ?

on the other hand if some of the increased wind activity associated with the dust storm continues shortly after much of the dust has fallen back to the ground, then
it could even improve the solar panel situation by "wind cleaning events"

[helvick]

Question for the experts (hevlick ?): how did the dust accumulation develop after past dust storms that Oppy observed  ?

Firtly I'm not an expert - just an amateur trying to understand something that intrigues me and would really love for a real expert to chime in if there are any reading.

What should happen (obviously) is that dust that is elevated by storms and dust devils will then settle out of the atmosphere over some period of time. Assuming that the Tau levels give some indication of that rate (which is not wholly correct I know) then looking at Spirit's Tau levels at the start of the mission it appears that this settling out process at the end of the last Martian Summer took about 140-150 sols. There was a pretty big storm centered on Hellas for most of December 2003 which cleared up just as Spirit landed. Tau at the Spirit Site started off at ~0.9, fell to ~0.55 by Sol 90 and then reached a stable level of around 0.3 on Sol 145 where it stayed until ~ Sol 350. One of the published MER papers confirms that the rate of power lost due to dust deposition during the primary mission followed the expected model which I take to mean that it dropped off at approximately 0.18% per Sol. So a big storm like the 2003 one at the end of summer would mean that the long term impact of dust loss moving through autumn and into winter would be around 30% which isn't too bad. It would also be fair to say that if Tau is around 1 when the Rover's first martian anniversary happens in a few weeks then we should expect the same ~30% dust loss over the following 150 Sols. It's worth pointing out that Opportunity is currently generating power in "the high 600's" which is 15-20% below what it would generate if there was no dust loss. IF things stabilise and follow the pattern from the start of the mission then the power output at mid winter will be about 340 Watt hours unless they happen to find themselves stopped on an unfavourable inclide.

[dot.dk]

Ok, the dust storm has hit Meridiani



Good luck Oppy

[djellison]

Youcha. I think a lot of that is because of the low sun causing an awkward stretch of the JPG - but the rover has got a LOT of camera-dust recently.

This one is stretched back a bit because of the missing data and it feels very very strange..

http://marsrovers.nasa.gov/gallery/all/1/f...23P1211L0M1.JPG


Doug

[OWW]

There IS more dust over meridiani:

Taken from http://www.arksky.org/alpo/index.php
October 30th:

Attached thumbnail(s)

 

[djellison]

Obviously MOC WA will be catching this lot, but it's fortuitously also Hubble time, Jim Bell et.al. had one and have another session, so they should have caught it in all it's glory as well - a nice flow of data if they get it right from Hubble, to MOC WA, to MERB

Doug

[Bill Harris]

It may not be curtains. This is a plucky little robot.

(putting on my best William Conrad voice) Will our intrepid explorers, Rocky and Bullwinkle succumb to the dust monster? Tune in next time...

I agree with Doug, the FHazcam image may be misleading. Argh! Only _that_ image online for Sol 627, and no others. But look at the second FHazcam image posted by Doug, the reflection of the bright sky off the polished aluminum piece is _very_telling of sky conditions.

We'll know more when the other Sol 627 images are up.

--Bill

[Guest_Sunspot_*]

When I go to the JPL RAW site all I see are broken links for the latest sol 627 images.

[Ames]

When I go to the JPL RAW site all I see are broken links for the latest sol 627 images. 

Grrr! Broken links, exploritorium not updating, what's happenning to Oppy????


Nick

[Guest_Sunspot_*]

Weird, they dont show up for me in any browser I try.

[dot.dk]

You have to insert "%23%23" in the filename where it says "##"

[jamescanvin]

ok, I'm confident that the Rover could survive during the duration of most dust storms but the  question is: how does the storm affect the accumulation on the solar panels *after* the storm ?

I'm afraid that the wind itself ceases long before the majority of  the dust (very light particles !) eventually falls out of the atmosphere:

this could be bad because all the dust  that had been kicked high up into the atmosphere would now slowly trickle out of the air like snow-flakes on a windless winter day, accumulating on the solar panels without the wind necessary to blow it away ...
...

When I talked to Steve Squyres a few months back he said that dust accumulation on the panels after a storm was not a consern. Lets worry about the storm itself for now.

James

[Bill Harris]

Heck, let's sit back and watch the storm.

Pass the popcorn, please...

--Bill

[CosmicRocker]

On earth, dust storms can definitely reduce available sunlight, but they are a real pain when it rains at the same time. Then it's time for a car wash. I'm a bit worried about accumulated dust, but also hopeful some dust will blow off the panels. It probably doesn't make a lot of sense comparing this dust storm to those on earth, though.

Both the original and the 'unstretched' hazcams posted looked pretty dusty to me. But I'm with Bill on this. Pass the popcorn and the Pancams, please.