How Much Driving Time? Options

[Cugel]

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...

[RNeuhaus]

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

[rschare]

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.

[helvick]

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.

[tedstryk]

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.

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