The pictures on Sundial are of different filters: LR1, LR2, LR3, LR4, LR5, LR6, LR7, and LR8. Maybe, due to different filters, we are seeing different clarity and colors on the top ball and also the borders of the surface.

Rodolfo

Maybe we should land a rover that has nothing but ball-topped poles of varying heights and see what ends up plastered to them as the sols pass. Call it "Maybe We'll Get Lucky".

It looks to me like that splat was created from a single collision, and that whatever hit it wasn't dense enough to damage the pole in any noticeable way.. Salty snowball?

Do students and others still use the sundials to tell the local time of day on Mars with? I haven't heard much about that since they first landed.

Visit the following URL to learn more about Sundial : Sundial details

1) It is used to calibrate and adjust colors of PANCAM (4 different colors on the corners)
2) It is used to see the martian's sky color (two halph circle mirror plates on the border)
3) To track the time on Mars watch by its star corona on the bottom of the pole. (only used by students).


The sundials, positioned on each rover's rear solar panel, will help the Athena team adjust the rovers' panoramic cameras. Scientists will use the colored blocks in the corners of each sundial to calibrate the color in images of the landscape so that Mars can be seen in its true colors. And pictures of the shadows cast by a sundial's center post, or gnomon, will allow adjustments for brightness.

"On Mars, you don't know what color anything is," said Nye. "The Martian sky is so pink that it makes everything pink, and so you want to know if the object you're looking at is really pink or if it's pink light bouncing off the sky."

The grayscale calibration rings surrounding the gnomon represent the orbits of Mars and Earth, with two dots representing the planets. A keen observer might note that the dots are in the positions that Mars and Earth would have been in at the time of the Surveyor landing.

Each sundial is inscribed with the words "Two Worlds, One Sun" and bears the name "Mars" in 17 languages, including Bengali, Inuktituk, Lingala and Malay-Indonesian, as well as ancient Sumerian and Mayan. Four gold panels along the sides of the sundials are inscribed with stick-figure drawings of people, as well as a message to future Mars explorers:

"People launched this spacecraft from Earth in our year 2003. It arrived on Mars in 2004. We built its instruments to study the Martian environment and to look for signs of life. We used this post and these patterns to adjust our cameras and as a sundial to reckon the passage of time. The drawings and words represent the people of Earth. We sent this craft in peace to learn about Mars' past and about our future. To those who visit here, we wish a safe journey and the joy of discovery."

Rodolfo

It looks like the dust storm is starting to fade. This image is posted here with permission.

I wonder why the 1971 storm was global and not any since?


Click to view attachment

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

I'm not as sceptical as the other Doug (in this case anyway). The broad dark bands don't look at all like wind tails or compression artifacts to me. The fact that they seem different between images doesn't mean anything, as these are two different images from different dates, so changes would be quite reasonable. The very narrow dark bands are the anatolia-style linear depressions. The Gusev streaks are curlier but that might be related to the topographic differences between sites.

Phil

I think that the differences between the Dust Devil and Wind Streak are of its traces. The DD *never* trace a stright line since it is subjected by the convencion of two different temperatures between the surface and the atmosphere which are very dynamic. Otherwise, the Wind Streak is of a constant or prominent wind and its force changes the color of surface in stright lines due to different kind of sand or dust on the surface. Then the typical atmospheric phenomenas: DD-> Gusev, SW -> Meridiani

Rodolfo

Admittedly, some streaks are jpg artifacts and wind tails but more of the dark tracks do curve and show characteristics of whirlwinds or dust devils. I suspect that the differences between here and at Gusev are caused by higher windspeeds on this flat plain and by the less-dusty armored surface.

The images do show the narrow anatolia lineations well. Phil's recent polar pans shown here do suggest that the "micro craters" seen Erebus-ward are indeed caused by sapping and not impact; I seen crater chains in this region.

--Bill