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?".