[X] My Assistant

[OWW]

Oh no...This is getting bad:

The new and potentially bleak outlook is a stark shift from the prognosis earlier this week.

The dusty squall has reduced direct sunlight to Mars' surface by nearly 99 percent, an unprecedented threat for the solar-powered robotic explorers. If the storm keeps up and thickens with even more dust, officials fear the rovers' batteries may empty and silence the robotic explorers forever.

Opportunity's energy-gathering ability has been slashed to a dangerous 280 watt-hours-enough power to light only three 90-watt light bulbs.

"The worst-case scenario is that enough dust in the sky decreases solar energy to the point that we have to shut down too many things to save power," Lemmon said. "The rovers keep their battery alive by keeping their electronics alive."

"The reality of the situation is that we're limited as to what we can do from the ground by cutting power use," Callas said. "If it continues to worsen and stay that way, it's a survivability issue for Opportunity. If Mars wants to kill the rovers, it can."

http://www.space.com/news/070705_dusty_rovers.html

[djellison]

What happened after the, admitedly much more modest regional storm, that Opportunity had in the 600-ish range - the one that made it sleep in late one morning?

Doug

[helvick]

What happened after the, admitedly much more modest regional storm, that Opportunity had in the 600-ish range - the one that made it sleep in late one morning?
Doug

The purple line is a 30 Sol moving average and the red line is a 50 sol moving average trend line on that. I had to do that in order to dampen out the noise sufficiently to see any trends at all but it means that the data in those lines is shifted to the right by 30 and 80 sols so keep that in mind.
It is pretty clear (to me maybe others differ) that stormier high Tau weather (such as seen around sol 370, 420 and 510) are followed rapidly by an increase in dust deposition rate from ~0.2% per sol to ~0.3% per sol. I would assume that the much more severe dust levels we are now seeing would result in higher deposition rates fairly soon but we'll only know for sure once it happens.


Also Pavel's comment on night time temperatures is correct - at Tau=2 night time minimum temperatures would be about 15-20 degrees warmer IIRC and I'd expect that Tau-4 would improve that again. The effect is the similar to that seen here on earth where cloud cover raises night time temperatures.

That said the stuck heater on Oppy means she draws a bit more juice than Spirit. Again IIRC the heater in question draws 15watts and is activated if the atmospheric temperature falls below -52C and stays on until it warms up past -42c - they use Deep Sleep to keep it off during the night however I think they still have to live with it being stuck on for at least two hours per Sol under the best conditions so Oppy needs about 30 Whr per Sol more than Spirit.