Does anybody know how much time Oppy actually can spend on driving on a single sol?

I remember that when she travelled from Eagle to Endurance crater it was no more than 1.5 hours per sol (or so), due to power limitations. I have no idea what the current power situation and battery status of Oppy allows these days...

About the same - perhaps a little less.

Remember - the rate of driving will also depend on what checks are inplace during the drive. Autonav is a lot slower than blind driving etc.

Doug

I guess that the driving speed will be much slower since the way from here to Erebus is not as flat and direct as the way from Eagle to Endurance. That way has lots of obstacles to pay attention to avoid being stucked in a tricky dune.

About the battery power, I am assuming that in the near future there will be more battery power since the Mars is approaching to Summer session. But, sometime, there will have dust storms that will affect the power supply to the rovers.

If not, some volunter is needed in helping to push the rover...

Rodolfo

Peak theoretical insolation would have been around Spirit Sol 521 even though the martian southern summer solstice is not until the 18th of August- this is because of the Mars orbital eccentricity which makes the seasons more lopsided than earth seasons. So

Both rovers were very healthy from a power perspective around the Spirit Sol 425 timeframe (panels were generating >800 Watt hrs per sol) but that dropped substantially by Sol 475 where Opportunity's power dropped below 600Watt hours again. I believe that trend continued through to around Spirit Sol 520 as the levels of dust in the atmosphere rose I haven't seen any numbers since then but at one stage during the Purgatory episode there was an update that indicated they were considering deep sleep mode again due to power concerns so power would have been 500Watt hours or below at that stage. I believe that situation has improved, visibility seems to be better over the past 20-30 Sols at any rate but I'd be surprised if available power was better than 600Watt hours for Opportunity right now.

I don't have detailed information on this (and would love some if anyone has it) but I think the rovers need 215Watt hours per sol minimum just to stay alive doing nothing. Imaging consumes 29watts/hour, communications 75Watts/hour, driving 38Watts/hour, 1-11Watt/hr for the other instruments and 55Watts for drilling. I've come across a number of 280Watt hours per sol as being the level below which the rovers will be forced to shut down. Most of this data is from Rupert Scammels MER Technical Data Page.

I suspect that this data isn't comprehensive - the above numbers add up to ~265 Watt hours daily minimum requirement for static operations with about an hour of imaging which sounds about right but the driving power requirement just isn't enough.

This NASA page says that the drive motors are 20Watt each which seems much more likely than the 38Watts total listed above. 150-160Watts seems like a more reasonable number for driving.

So if Opportunity is getting 600Watt hours per sol from the panels it can probably stretch to about 2 hours of driving per sol.

there was a very interesting analysis of the Rover's power situation/extrapolation
posted by helvick in another thread.
It takes into account seasonal effects and gradual attenuation by dust accumulation on the Solar panels.

http://www.unmannedspaceflight.com/index.p...ype=post&id=580

thread:
http://www.unmannedspaceflight.com/index.p...722&#entry10722

from this analysis it can be expected that we won't drop below the critical
300 Watts mark until Sol 700 for Opportunity and Sol 770 for Spirit.
(assuming no "assistance" from further "cleaning events" on the other and no
major dust storms on the other hand)

So, reaching Victoria by Christmas is a realistic goal, at least as far as battery Power is concerned.

Thanks all!

So, if I got this right, with nuclear power instead of solar, we could probably drive all day long (?). This means that MSL, even with the same speed as MER, could travel substantially further, up to 1 km. a day. Of course, if the terrain and software permit it...

Well, I still like those solar panel wings! An elegant idea, living of local resources, and it gives the rovers such a cute appearance. I bet that in a space probe beauty contest they would win by some margin. (Sojourner at 2?).

Well, what I have learned that the Mars Scientific team is not interested to drive fast and farther but only to stop as often as to taste everything related to science (minerology, morphology, etc.) that is found on the way. Some day, no drive at all and some day may drive far.

Rodolfo

It would be nice if people at large weren't so frightened of nuclear power, especially in regards to probes that are flying millions of miles away.. I guess Three Mile Island and Chernobyl and that whole 'Cold War' thing turned people off of the nukes. Someday, maybe.

I'd like to just see pictures of Mars at night from the surface. You could run headlights. You wouldn't need a rechargeable battery. You would hardly even need any radioactive material. You could seal the power plant to such a degree that it's ridiculous to imagine that anything could ever leak out and 'turn you into a mutant'. Besides, God invented radiation so He could make even Better Versions of Himself.

Someday!

Todays flight director report mentions that the power situation has improved.
He attributed the improvement to clearing skies and to some more cleaning
events!!

it would be the *perfect* design if it also included some cleaning mechnism to prevent dust accumulation on the panels.
This would mean virtually unlimited exploration during the course of many years and over great distances.
Especially if combined with massive redundancy and simlpicity/robustness against hardware failures or wear/tear: think of, say 10 MER-like self-cleaning-solar-panel powered rovers distributed all over the planet ...

This actually was an issue discussed before in a thread that i forgot what title it had. It has been under consideration by rover builders to try to incorporate some mechanism or system that takes care of a clean solar array for the long run. It seems so stupid that it wasn't built in (was my first idea). Especially because it seems like the most probable cause of rover-death in the end. However, it is not as easy as you (and I before) think.

First of all: NO one expected both of the vehicles to be fully operational after this long. They were designed to last 90 sols and 600 meters of driving distance. Taking this period of time in mind (and the experience of dust accumulation on MPF), there wasn't any concern about the dust. "Probably something else will finish them", must have been the consideration.
Secondly: there's been some research on solar arrays that repulse (is that english?) fines from the arrays by means of electromagnetic forces (and make use of the mineral magnetite abundance in the fines). This hasn't been studied thoroughly enough to be incorporated in the MER design however and also costs a lot of energy. There's also other ways to do it, like incorporate a "rolling foil" that renews itself like an expensive hotel "toilet seat hygienic system", however, this would be far too complicated to fit in because of the folded up configuration combined with the treamendous amount of obstacles on the rover deck (antennas, mast, TES target, magnets, pyro's, wires, sundial). One could think of a pressurized vessel with inert gas (like nitrogen or a noble gas) that could blow the arrays clean every now and then: this idea is nice but has the same problem as most of the others: it is simply too heavy to fit in AND to complex to integrate with the design......

Let our minds keep on cracking this issue until someone calls "Eureka" and finds something that really keeps them clean forever.... That would certainly maximize the amount of available driving time each sol....until something else breaks.

Basically the mass, volume and money spent on a system to try and remove dust would be better spent on a) not taking up Whr's cleaning the arrays, and haivng larger arrays in the first place

Doug

To be honest, i don't know if a can agree. Larger arrays get dusty as well and eventually will be worthless too. Unless: cleaning events are common. Then there's not a point to discuss at all. But since we don't know if that's something we can rely on, i think it's good to at least keep thinking about a solution. The idea of a robust system that has enough energy to keep itself clean sounds better to me than a system that (in the end) will die because of dust. Offcourse all robots will die because they can't be maintained. But the idea that a rover will die of another cause than dust on it's arrays sounds good to me. In other words: Spirit and Oppy prooved to be very robust mechanically and elektronically and if we could think of a solution that is not too heavy and with a simple design, we might end up with rovers with a life expectancy exceeding that of RTG powered ones (4, 5, 6 years ?), and thereby also saving HEAVY RTG's from the payload (and making antinuclear activists happy as well).....

Personally: A combination of RTG's to boost the energy budget during a primary mission of a rover in combination with a self cleaning solar array of modest size to provide the mission a long extension (maybe even as a stationairy platform for wheather, imageing, etc.) afterwards is what i am dreaming of.....

This thread is not about driving time though.....often i don't know where to post my ideas and thereby drifting of topic easily sorry. Maybe we start a new topic elsewhere on "how to make rovers more durable ?"

A combo of RTG's and Solar Arrays doesnt make any sense.

RTG's last a long long time. Consider the Viking landers. 4 years, and more.

I think cleanable solar arrays are just pointless. You want a very long duration mission - you give it an RTG. You want a short mission - then arrays are good, and if they get kept clean, well hell - BONUS

Doug

Every time you wish for a solar panel cleaning system, consider 1.) weight, 2.) complexity, and ask: "Which scientific instrument on these rovers would I trade in return for the mass and volume for a dust-removal system?".

then what about a simple "windscreen wiper" ?, lightweight (maybe 0.1 percent of rover mass), negligible complexity and quite effective

"Simple".... Only if the configuration of the panels is simple and without obstructions..... and what if it just smears electrostatically attracted dust around?

Mars Surveyor 01 had the "MECA" <I think> experiment, including test plaques of material treated with various dust repellant ideas, and a grab bag of other engineering micro-experiments to get some of the info to help design things that we know will work.

After the MER rovers, we KNOW that a system of air-jets could easily puff dust off panels. Only question would be design. But we didn't know that before.

A "windscreen wiper" (or "windshield wiper," as we Americans call it) woud end up, over time, scratching the coatings of the solar cells so badly that they would lose effectiveness. (Try tossing fine rock dust on your windscreen and clearing it with the wipers -- you end up with thousands of tiny scratches in the glass. And that's glass, which is more resistant to such scratching than the materials from which solar cells are made.)

You would also have to design your solar cell surfaces so that they have no cracks or crevices, and nothing that protrudes up above them -- they would have to be very flat, smooth surfaces. Ever seen a solar cell array? They're not all that smooth -- and making them smooth would probably add weight, too.

I think the best dust-clearing device you could come up with would be a small compressor that takes in Martian air, compresses it into a bottle, and (when you need a cleaning) is commanded to blow the air out through vents positioned to duct it across the arrays. Or perhaps just a bottle of compressed CO2 instead of the compressor. A compressor would let you clean your arrays as many times as you want over the lifetime of the vehicle, while a pre-loaded CO2 bottle would only be good for "X" number of cleanings.

But Doug is right -- such a system would likely weigh as much as one of the major sensor packages you want to put on your probe. So you either have to 1) accept the sacrifice of one of your sensors, or 2) increase the mass you can land on the surface by *just* enough to include your cleaning system. Since the second option makes the whole mission more expensive, you'll probably end up getting stuck with the first.

And while you're deliberating on solar cell array cleaning systems, you have to face up to the fact that any solar-powered Martian lander could have its power cut down to below-survival levels by a planet-wide dust storm, whether or not you can clean the arrays. If a really energetic global dust storm occurs and the atmospheric opacity increases beyond a given level for too many sols, a solar-powered probe may simply die. And you've sacrificed your sensor for nothing.

So I'm inclined to agree with Doug -- for longer-duration missions, RTGs are the way to go. For shorter-duration missions, solar power without array cleaning is acceptable, since you're going to get your primary science return very early on. Besides, it seems like Mars is willing to provide enough wind to clean off solar arrays at frequent enough intervals to make extended missions for even these short-duration probes more likely.

There are ways of "tweaking" solar-powered probes, though, to try and get the longest life out them. For example, I believe the MERs use tiny radioisotopic heaters within their main "boxes" to keep the electronics and batteries comfortably warm. Those provide heat without using electricty, thus reducing power consumption needs. The MERs only have electric heaters in places where you can't easily use a passive heating system, like on the IDD. I'm sure there are other ways tweak solar-powered landers to enhance their lifetimes that are both easier to implement and weigh a lot less than solar array cleaning systems.

-the other Doug

Right, i agree on almost everything said. Except: the payload being unable to increase. Ofcourse MER could have been made 5 kg's more heavy.

It's a matter of money. I see it like this:

Better a 1200 sol mission for 900 mln (an extra 100 million for 5 kg is enough isn't it ?), then a 800 sol for 800 mln. It's not only about $'s, it's about $ per sol.

It's not necessarily linear -- the easiest way to increase payload is to use a bigger booster. The MERs pretty well maxed out the capabilities of the Delta IIs used to launch them, and as of 2003, there really were no larger boosters available.

Delta IIs are proven technology, relatively inexpensive (compared to most of the rest of the options), and let you send something about the size of the MERs to the Martian surface.

Heavier-lift booster configurations (like some variations of the Delta IV and the Atlas V) are just starting to come on line, and will probably be used to launch MSL. But they're new, the companies that produced them spent a *lot* of money to develop them, and they're going to be quite a bit more expensive than the Delta IIs, especially at first. Whether that's $100 million or less, it's still significant.

Also, increasing the size of your lander package by a few kg isn't just a matter of adding a little more fuel to your rocket. Every pound you land on Mars costs in increased mass of *all* of the previous stages -- in MSL's case, the Skycrane would have to carry a little more fuel, the wheel suspension will have to be rated to survive touchdown with 5 kg of increased mass, the TMI stage will have to be a little more powerful, and since it will have to carry more fuel, the stage(s) of the booster will have to be more powerful and therefore heavier -- as you backtrack to the rocket sitting on the pad, every pound of extra payload you want to land on Mars can add hundreds and even thousands of pounds of additional fuel required to get it there. (To land less than 20,000 pounds on the Moon, Apollo had to launch a rocket that weighed nearly seven *million* pounds at lift-off. And it takes less overall energy to get a pound of mass to the lunar surface than it does to get it to the Martian surface.)

And on top of all of that, when you increase your lander mass and move to a new, bigger booster, you have to design all of the interfaces from scratch, you have to redesign your cruise stage, you have to validate and possibly redesign your parachute, you have to validate your heat shield configuration -- all of those things can make moving from a Delta II up to a Delta IV or an Atlas V more expensive than the simple increased cost of the booster.

So, maybe an extra $100 million would cover it. Maybe it wouldn't. We'll eventually transition to heavier-lift boosters, but y'all have to understand that this will inevitably lead to increased development and mission costs.

-the other Doug

AMEN-squared with DVandorn's comments. The rovers are maxed out on size and mass. The airbag and hard-lander system of MER and Pathfinder is ultimately a horrible set of nested "russian dolls". Rover inside lander, lander wrapped in airbags, Everything in heat shield together with rockets and chutes and all the rest, carried there by the otherwise totally useless cruise stage...etc etc.

Specific point: The Landers are sized to fit inside the heat shield which had the absolute maximum diameter possible for the aeridynamic fairing on the Delta that was budegeted for the launch. HARD limit, there, among other places.

We were talking about trying to find a simple, possible and fine solution for keeping the solar arrays clean. Mars is a dusty place, rovers are EXPENSIVE things, it ought to keep itself working up there. It's a matter of priorities. Nothing more, nothing less.

Incorporation of a small (and when i say small, i mean small) compressing unit to maybe even double the lifetime of a rover, had to be onboard to my opinion. It has to do with creative (and on time) thinking about what HAS to be done. No one can convince me that MER couldn't be made lighter. It can. As long as you want it, and as long as you define a cleaning device as priority.

And i simply do not believe that the launcher limitted the incorporation of such a device. It too much into margins.

A dutch saying: Where there's a will, there's a way.

PS: I know how much calculating was done to make the MER payload possible for the launcher used. To my opinion (but i am not THAT well informed to know it for sure) however, the issue of dust and the way it kills spacecraft, should have been a more integrated aspect from the beginning of the design.

Yes. The priority was the 90 day primary mission.

Are you suggesting shot-blasting the solar arrays with compressed martian air laden with dust?

Isnt the point mute anyway?

The rovers are still working - it's more likely a mechanical failure will kill them off - not a lack of power.

Doug

And if i recall it well now, these 90 days were based on the assumption that dust would kill them off ! And that's exacly what whould be prevented in some way (i did not say that i know how, by the way).

But what am i complaining about ! Deep into 500 sols, we'll be soaked in data for years. I just can't stand the idea that these incredible machines, on a sun backed surface eventually will run out of energy....

Will they ? Maybe the cleaning events will continue.....

About the dust loaded atmosphere: i think even at a global duststorm, there still will be enough watts left to stay awake.

Yes i do. Just like a dust laden dust devil can clean of dust from a dust laden array.

What's mute mean ?

You're right. Sol 548 & 528. This threat is getting a little over the top, me being guilty as well. But al these beautifull sols, images and science makes me like a little child: wanting more and more (for the same money ).

How about a way of simply tilting the rover? Like maybe rear it up on 4 wheels so it's angled into the wind? Spirit probably got cleaned because it was angled while sitting on the hills. Look at Opportunity though. It's on flat terrain, and last I knew (long time ago) was that its output started dropping once it left the tilted ground of Endurance crater. Maybe just rearing it up, angling it slightly against the wind, would allow it to get a cleaning.
If the computer animation of the rover's landing and egress process is accurate, the rovers already have some capability to do this - it had to stand on the back 4 wheels while the front two unfolded from their stowed positions.


I believe the term sought was "moot point."

There has been a lifting mechanism on the lander to do this. You can't do this anymore.

IMHO: Use RTG's for long lasting missions. If you have to use solar arrays, the "easiest" cleaning is probably by some pressured gas (not air) from time to time. Make the deck flat and put some nozzles at strategic positions. Sure it adds complexity, but better than waiting for dust devils. But worse than RTG's.

Analyst

I believe they could only do this because it was still attached to the lander by pyro's. I don't think they can do it now (they probably would tip over on their noses). But i'm not sure about the centroid point of the rovers and the load distribution on the wheels.

By the way, there's been quite some research on it by the way by Geofrey Landis et al., indicating to me that it is an issue that's worth considering (at least) for future missions.

http://powerweb.grc.nasa.gov/pvsee/publica...rs/removal.html

One of the articles in the list at the end (references) of GL deals about the angle of a surface and the influence on dust accumulation. A thread before we discussed this and we found out that tilting an array doesn't do so much: it will accumulate dust anyway: just like sides of rocks (Gusev) and the pole on the sundial are dusty on the sides as well. I think (but don't know for sure) however, that driving, and thereby vibrating, on a slope removes quite some dust.....

maybe a mechanism that can tilt the array and shake it.

I say we send a cleaning lady with a gentle feather duster in an accompaning ship to prevent the possibility of mechanical breakdown and an attendant to massage her shoulders if she were to get fatigued.......





Get a grip an reality here guys, they could have been a crater liners 500 sols ago like MPL became...
.. or they could have blown a diode after 90 sols like Pathfinder
...or
...or
..or all the other things that could have gone wrong. The more complex you make it the lower your chances of trouble free operation.
My bet is that the power supply will outlive the hardware

And look at the power trend - essentially sustainable at between 400 and 700 whrs. That's basically enough.

It wont be a lack of power that kills these things - it'll be a mechanical failure.

Doug

A simple dust removal mechanism maybe isn't such a giant leap from the MER already on Mars. Most of the elements of such a system can be adapted from parts of the science payload. The RAT spins at 3000 RPM - why not integrate some kind of impellor unit that blows air out the back while it’s spinning (like my power drill, jigsaw, orbital sander etc..!). Then adapt the reach of the IDD to reach the deck, engage the RAT, compressed air blows out the back, and move the arm for total coverage.

/back to lurking

To enable the IDD to reach the whole of the solar arrays would mean making it three times bigger and three times heavier. It wouldnt fit.

Doug

True.

All the options thought trough (and reading GL's articles) it might not have been such a good idea for MER after all. It seems to work out fine indeed with the nowadays array output in mind (which is purely due to being lucky).

It might be an option for future missions without RTG's however. What about Phoenix ? Still 2 years till lanch window....and we're talking about a pretty tight energy budget up in the shivvvvvering north.

If there is no sun at all (in northern winter), you can have the cleanest arrays on the planet. Won't help.

The energy budget up north is not that bad. They just have to point the solar arrays at the sun. The main difference is how much atmosphere they have to look through. Now consider that no amount of cleaning will help when the northern winter arrives and solar panel cleaning becomes a non-issue.

RTG's are the way to go...

I've wondered about the lenses on the Haz-, Nav- and Pancams; I guess that they accumulate dust, also. That would add a degree of "softness" to the images, which could be compensated for with image processing. The Hazcams (rear, especially) do show some "blotchiness", but I've not noticed image degradation on the other cameras. Are there lens covers or cleaners on the cameras?

--Bill

On the Microscopic imager is a lens cover (probably because the RAT is so close to it) and i don't think the rest of the camera's have special covers.

I've met him. In person.

Interesting discussions about different options on how to improve the power of array solars in order to avoid in using the heavy and "relatively" dangerous RTG.

What happens if there is a planetary dust storm that might last a long time?
- The Sun power will be more restringued during these days. The RTG is favored
for this situation.

On the other hand, about my comments about on this topic:

1) Windshield. Forget it. It need water to clean away perfectly the sun power panels.
2) Raising to vertical position and shake the wings sun power. Extra weight due the adding electrical motors to raise and also to shake wings.
3) Martian air compressor. The best solution for its simplicity and about the weight, it might be lower than the option 2.
4) Go for a zone of dust devils and wait of being hit. Never know when! and not all place has dust devils. (Gusev has most often dust devil than Meridiani Planum). Not good solution.
5) Look for some big stone and climb on it so that its position is, as an example, 40 degree of inclination and turn an vibration engine to shake off the dust. Not as effective as the solution 2 but it add less weight to the rover.

Anyway, I think that the best solutions to extend the power supply are not only of one idea but any more ideas:

1) On the surface of the sun power must have some kind of magnifying optical in order to absorbe more light and hence provide more sun power. I am not sure of that this idea is valid. The magnifying optical concentrates the tenue light ino an radius of strong linumination. But I doubt the result would be the same for both ways.

2) As the Martian has wind, the top of mast must have some kind of helix. The martian is somewhat windy (around 10 m/s on the surface). It might add some weight to Rover but in some places, it would be very helpful to provide "aeolein???" power (air power). I doubt if that solution might be effective since the martian air is so light to push the helix to rotate...some very light material and very low friction, it might be rotating and thus hope to provide some few worths of wats/hour.

Rodolfo

Isn't this all kind of a moot point?

I thought that the batteries only have a maximum number of charges they can handle (and we're coming up on that limit soon). So, even if you could get a cleaning of the array's, and a larger electrical charge, the batteries are eventually going to die anyway.

The "To Clean or Not To Clean" discussion again. :-)

Just remember that the primary mission objective was 90 days with only the very optimistic thinking even one rover would survive twice that long. The best estimates they had at design time showed they should have been getting into serious power budget problems at around Sol 200-250. And they did - Spirit hit rock bottom at that stage (288 Watt hours on Sol 204), Opportunity fared better because it was sheltered in Endurance and angled nicely for optimum solar power but still dropped below 450 watt hours in mid winter. Every kilo spent on a cleaning system would have impacted somewhere else, maybe fewer cameras, less mobility, no mossbauer or what ever. I really think the design trade offs that were made were excellent and the fact that the rovers are still operating after 500+ sols is an amazing achievement.

SS's latest comments about the Mossbauer's Cobalt-57 gamma ray source [half life of 271 days] shows that many of the non mechanical components are destined to continually degrade and a lifetime of 500+ Sols was really on the outer limits of anything they thought would be achievable. It's been pointed out before that the Li-ion batteries probably have a useful life of no more than 1000 charge cycles and that might be the thing that finally does them in.

Vertical\Sun tracking arrays have been considered, This study goes into a lot of detail on the factors being considered for a Polar Rover .

Phoenix is a short term mission being done on the cheap with already proven technology- I don't think any amount of gymnastics with solar arrays is going to allow it to last much beyond it's 90 sol primary mission and would add both cost and risk with no benifit - 70 days or so after the end of the primary mission it's going to be in near darkness 24.66 hours per sol and solidly frozen.

I didn't intend to jump into this discussion about solar cell cleaning, but if you wiggle a lure in front of a fish long enough, somethimes it will strike out of frustration.

At any rate, aren't the solar cell panels equipped with hinges and motors that lowered them into a horizontal position in the first place? And if so (and I don't mean on this mission), wouldn't it be possible to use this same mechanism to raise the solar panels back to a vertical position -- perhaps several times -- to at least shake off much of the dust?

I realize this is a stupid idea, so someone please set me straight.

Glenn

Hey you, it's a stupid idea !
No, seriously, the participants in this discussion (which know a hell of a lot about the machines) stated, that the amount of energy from the arrays is not going to be the bottleneck. I might as well go for that opinion, since, indeed, after almost 550 sols of ops., there's STILL no reason to be concerned about the dust on the solar panels. Next year there will be, probably, but what the heck, we will have had such a treamendous amount of data......we should be satisfied.

If, however, both rovers would have ended after 100 sols (just after primairy mission) due to dust cover on the arrays, I AM SURE the next solar powered rovers would be equipped WITH a cleaning system.

But the great experience they have now with the energy budget of these two sweeties does not require elaborate effort for that.

Better to invest in optimization of EDL, RTG's, instrumentation and mobility performance for the next generation rovers.......

Marcel.

As I undestand it - THIS misison couldnt as the arrays locked into place when they were rotated into position. Runing those motors backwarsd wouldnt work.

the next solar powered craft is Phoenix - and it has some fairly funky arrays that dont really fold 'up', but more concertina in a circle. But the misison is going to be killed off by the lack of light before dust ever becomes an issue

Then we're on MSL and it's RTG-o-rama



Doug

The dust is finer than talcum powder, way way too fine to easily just be dumped off tilted and shaken panels as if it was fine sand.

There's no reason available surface on a rover couldn't be covered with thin, lightweight solar cells as "supplementary" power. Note that Viking's RTG's produced only 70 watts each, at the start of the mission <somebody check my figures...> 140 watts x 24 hours isn't an enormous amount of energy, and supplementary solar could help, if it doesn't eat up too much weight.

I don't agree. Look at opportunities wheels at the moment. The have been milled around in extremely fine dust (especially lately) and at some moments they were filled with dust. And now: they look like being from the dishwasher: completely clean. On Mars, it's not like on earth, where atmospheric water vapour easily clods together dust. Dust on Mars almost falls off just as easy as it settled down. It's a great benefit of roving on Mars: it's dry (also, you don't need to coat your chassis with tectyl against rust ).

3360 Whrs - is a lot more than MER

Doug

True. While there is a slim chance it might wake up after the winter, this highly, highly unlikely.

Unless they put an RTG on the craft to keep it warm during hybernation
Probably too heavy as well......