Indeed the dust storm is over and a fresh new cleaning event was in order

Rover update at JPL/NASA

http://marsrovers.jpl.nasa.gov/mission/sta...tml#opportunity

It's left over from the "cleaning event."

720 watt hours is nice and healthy, the cleaning event seems to have boosted Oppy's energy generating capacity by about 10%. Before this dust storm she was generating somewhere around 670 watt hours and the total insolation has dropped slightly so I had been expecting that she would return to around 650 watt hours when the dust cleared.

helvick,

what would be your best estimate of Oppy's remaining life time, if it were limited by solar power alone ... a) without further cleaning events or assuming one or two additioanl 10% cleaning events during the remaining life time ?
From your latest chart it would seem that we could expect solar power to last well into February, right ?

Nirgal
... who still can't stop dreaming the Victoria dream

I now think that it will be well past February, in fact I don't think that declining Solar power will be an issue at all until very close to mid winter (around the start of July 2006). She now has a very good chance of being able to generate enough power to survive for at least another martian year and a half. Other things are probably becoming more critical though but power is definitely looking very good indeed.

A few weeks back I estimated that the power levels at mid winter on her second year would be around 260 Watt hours but that was based on the then current level of dust loading. This cleaning event has added about 70 watt hours of capacity at the moment and if the pattern of dust deposition between now and Sol 870 (the Sol with the lowest insolation ~ July 5 2006) follows the pattern from Sols 1 to 196 then my estimate needs to be increased by 35-40 watt hours.

So I think we're now looking at a minimum of 295-300 Watt hours for a few days in mid winter. That is survivable, particularly if the planners\drivers can find some handy 10-15 degree north facing slopes to pitch out on for a week or two in the depths of winter.

I had the impression that Opportunity was close to the Equator, and that we are using the term "winter" to denote the time period when Mars is near aphelion. I don't think that being pitched 10-15 degrees could help much of anything, except perhaps to allow gravity to help the dust to roll off the solar panels.

Heck they can find a slope like that on any large sand dune.

That raises another question though. Does anyone know if the wheels can be partially retracted again? (For example to create an artifical tilt to the rovers) or did they permanently lock into place upon initial deployment?

I could be wrong, but straight from memory I think some pyros were fired to deploy the wheels, so probably they can't be retracted back.

Locked on deployment..


In terms of power, was there an issue of battery cycles and can we tell if they are degrading?

When I'm talking about "winter" I'm referring to the Southern Hemisphere winter. Sorry I should have been specific, I was being sloppy.

I've tended to refer to Winter instead of being specific because there is a "seasonal" cycle even for Opportunity. You are correct about winter in this context being when Mars is near aphelion but the seasons that result from obliquity still have an effect on insolation even at the equator. The top of atmosphere insolation level varies according to the mars:sun distance (going from ~500-~700 watts/m^2 from aphelion to perihelion) but the surface insolation at any point also varies as the planet's obliquity causes the suns Zenith angle to change throughout the year. For any point (even one on the equator) this leads to a change in insolation with two maxima during the year (at the equinoxes), this effect is smaller for Opportunity than the first effect but the sun's zenith angle in Mid SH winter is 25 degrees (to the North, at noon).

Solar panel efficiency is improved under such conditions by ensuring that the panel is tilted towards the position of the noon sun. This is particularly important during the Martian Southern Hemisphere winter season because Tau drops to around 0.3-0.4 over much of the planet at that time and when Tau is low solar panels become very sensitive to the incidence angle of the incoming sunlight. When Tau is high, as happens during the SH summer, the solar panels generate a significant percentage of their power from diffuse light and do not suffer significantly if they are not precisely aligned to the noon sun.

The difference might not seem that much (40-50 Watt hours in mid SH winter) but the difference between pointing in a favourable direction and an unfavourable one can easily be 80 watt hours. Spirit's power levels dropped briefly from 370 watt hours on sol 203 to 288 watt hours on sol 204 because a drive terminated early and left her pointing in the wrong direction. Likewise Opportunity benefited extensively during the last winter season because she spent most of her time pitched between 15 and 20 degrees on the North facing inner slopes of Endurance.

%&*#$ pigeons are everywhere!

I believe you are referring to these Martian pigeons?

On dust devils-- or the failure to see them-- at Meridiani: I was looking at MOC imagery for examples of the anatolia features and found these two images near the Oppy landing site. A histogram equalize was done to enhance low-contrast features and behold, (apparent) dust devil tracks.

FWIW; open to interpretation. But applying the Duck Criteria....

--Bill

I remember them being designed to be able to do about a 1000 cycles. That (to my opinion and guess) is going to be THE problem in the end. As far as i can tell, the degradation of the batteries can be assessed easy when charge and recharge currents, -times and -characteristics are compared over time.

Is this data available to the public ? Can we ask for this numbers in some way ? It's pretty important considering how much more adventure we can expect on the long run.

There might be a possibility of solely operating on solar energy directly from the arrays when batteries get worse, there will be no (or not much) energy left at night however to prevent the Warm Electronic Box to drift outside temp. design limits. Eventually, they'll probably freeze to death.

But that might take another Martian year !

Open to interpretation is right... frankly, I don't see dust devil tracks there. I see wind tails and I see compression artifacts. Note that there are two very obvious dark lines in the image on the right that don't appear on the image on the left -- a sure sign that these are being enhanced out of the noise.

There's nothing of the curly-q type of tracks you see, for example, at the Gusev site. Whatever shown in these images that's true wind effects, IMHO, is from straight-line winds.

-the other Doug