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#301 2018-06-30 16:28:43

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,440

Re: Going Solar...the best solution for Mars.

Well the Curiosity's top speed is 0.14 Km per hour. So, I was being cautious.  If you've got some precious cargo you're towing, I think you'd probably want to go pretty slowly.  Once the boulders and rocks are cleared, then yes much faster speeds should be possible.

kbd512 wrote:

Louis,

I can't think of any reason why rovers can't travel at a slow walker's pace on flat and level ground.  If 5kph is as fast as a rover can manage, then you're better off bunny hopping along in .38g.  I think 20kph is a more reasonable travel speed for a human operated rover.  If the ground really is that littered with debris, such that it would impede a rover traveling at parking lot speeds, then you're not landing BFS there.

Anything that requires the level of effort associated with the construction of the solar power array is not a sacrificial tool.  The BFS integrated propellant plant may not see service as a rocket afterwards, but it performs a vital function for crew return and serves as a source of spare engine parts for the passenger carrying BFS.

Last edited by louis (2018-06-30 16:33:06)


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#302 2018-06-30 17:34:37

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 5,876
Website

Re: Going Solar...the best solution for Mars.

One disruptive technology we've talked about since year 2000: quantum entanglement communicator. Using electrons contained in a quantum well on a microchip. It's been tested with photons in a fiber-optic cable, it works. Theoretically photons should have infinite range, electrons will have a finite range, but no one know how to calculate that. Advantage of electrons is no cable. This is similar technology as quantum computing, but not exactly the same. It would provide instantaneous communication over whatever distance it works. Real time communication to a rover means a human operator on Earth can drive it. That allows a lot faster drive. It also allows telepresence. So why hasn't it been done? And don't tell me it can't work because tests with fiber-optic cable already worked, and quantum computing is progressing.

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#303 2018-07-01 05:31:16

kbd512
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Registered: 2015-01-02
Posts: 3,164

Re: Going Solar...the best solution for Mars.

Robert,

I'm sure anything can be done with enough time, money, and research effort, but counter-factual quantum communication using the Quantum Zeno effect was only experimentally achieved last year.  There's at least another decade of effort before a reliable communications system is ready for testing.

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#304 2018-12-08 21:32:25

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,741

Re: Going Solar...the best solution for Mars.

was looking for the nuclear versus solar topic

https://www.reddit.com/r/spacex/comment … ear_power/

image018.jpg

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#305 2018-12-09 07:30:44

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,440

Re: Going Solar...the best solution for Mars.

The InSight lander is currently generating about 0.5 KwHs per sq. metre per sol in a non-optimal insolation zone.

On that basis a PV array of 100 metres by 100 metres, 10,000 square metres, would generate 5,000 KweH or 5 MweHs.  I would estimate that with that you could generate steady power throughout the day (using batteries, or methane/oxygen generation) of say 0.25 Mwe or 250 KweHs for a human mission to Mars.  However with a PV powered mission you would design it so that power was used mostly at PV peak, rather than lose lots of power to battery generation. So, you'll probably see power being used at 1Mw during the peak period - that would be when you heat water, run the dishwasher, produce propellant, recharge rover batteries etc.  You'd  probably see power used in the range of maybe 125 Kwes to 1,000 Kwes."

To produce 1000 tons of propellant you need an averaged constant of around 122 Kwes throughout the sol for 700 sols (although of course that's the average -  the power intake could vary to some degree). So a 10,000 square metre PV field could meet that requirement, but you would need possibly to increase it slightly to allow for the impact of any prolonged dust storms.  The real constraint is not so much the power output but rather how big you make your propellant manufacturing kit - I am presuming the more you make it fit peak power output, the more mass of equipment you require. So although you might have 1.25 Mwes to spare, you might not want 10 times the size of kit suitable for steady power output at 125 Kwes.  So you need battery or other storage to ensure constant output and a PV system you do have to factor in dust storm outage which could reduce insolation for 80% at the extreme, certainly by 40% over months in worst case scenarios.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#306 2018-12-09 07:42:24

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,804

Re: Going Solar...the best solution for Mars.

Louis,

Some years ago now, a local robotics competition for high school students included a challenge to sweep dust off solar panels.  I have noticed the absence of robots on Mars to perform that function.  That's not a criticism of course, because the missions currently on Mars have been scrubbed of non-essential functionality.  However, the next generation might well include robots dedicated to maintenance of solar panel arrays.  A potentially useful cleaning method would be jets of atmosphere across the panels, to try to reduce abrasion of the surface of the panels.

Edit: If a private enterprise were looking for a project, to test a solar panel cleaning robot, here is a suggestion:
https://mars.nasa.gov/mer/mission/statu … tyAll.html

(th)

louis wrote:

The InSight lander is currently generating about 0.5 KwHs per sq. metre per sol in a non-optimal insolation zone.


To produce 1000 tons of propellant you need an averaged constant of around 122 Kwes throughout the sol for 700 sols (although of course that's the average -  the power intake could vary to some degree). So a 10,000 square metre PV field could meet that requirement, but you would need possibly to increase it slightly to allow for the impact of any prolonged dust storms.

Last edited by tahanson43206 (2018-12-09 07:53:17)

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#307 2018-12-09 15:32:32

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,440

Re: Going Solar...the best solution for Mars.

I think that has been an assumption of previous discussions - that there will be a system to remove dust from the panels. Of course rovers haven't had the benefit of service robots. I think they have relied on some gradient manouevres to remove the dust. If we have ultralightweight PV film suspended on angled wires, tugging at the wire would probably be enough to shake off a lot of dust.


tahanson43206 wrote:

Louis,

Some years ago now, a local robotics competition for high school students included a challenge to sweep dust off solar panels.  I have noticed the absence of robots on Mars to perform that function.  That's not a criticism of course, because the missions currently on Mars have been scrubbed of non-essential functionality.  However, the next generation might well include robots dedicated to maintenance of solar panel arrays.  A potentially useful cleaning method would be jets of atmosphere across the panels, to try to reduce abrasion of the surface of the panels.

Edit: If a private enterprise were looking for a project, to test a solar panel cleaning robot, here is a suggestion:
https://mars.nasa.gov/mer/mission/statu … tyAll.html

(th)

louis wrote:

The InSight lander is currently generating about 0.5 KwHs per sq. metre per sol in a non-optimal insolation zone.


To produce 1000 tons of propellant you need an averaged constant of around 122 Kwes throughout the sol for 700 sols (although of course that's the average -  the power intake could vary to some degree). So a 10,000 square metre PV field could meet that requirement, but you would need possibly to increase it slightly to allow for the impact of any prolonged dust storms.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#308 2018-12-09 17:07:28

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,741

Re: Going Solar...the best solution for Mars.

So mission to resurect opportunity and Spirit, such a repair mission could not only be a proof of concept but to stop the calls of hoax from those that do not believe.

For Mars Loui solar Watt Hours are not guaranteed and we should not count of it being the case...

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#309 2018-12-09 20:00:18

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,440

Re: Going Solar...the best solution for Mars.

I believe it's true all the solar powered rovers have extended their lifetimes way beyond the original designated target - sometimes by 10x or more. 

SpaceNut wrote:

So mission to resurect opportunity and Spirit, such a repair mission could not only be a proof of concept but to stop the calls of hoax from those that do not believe.

For Mars Loui solar Watt Hours are not guaranteed and we should not count of it being the case...


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#310 2018-12-09 21:15:25

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,741

Re: Going Solar...the best solution for Mars.

Survival of solar powerd robots will and are not the same as for human life.

Here is the solar power comparison for what we have sent...

589px-PIA22835-MarsProbes-SingleSolGeneratedEnergy-20181130-corrected.png

Pheonix had the same panels but due being so far north and winter it could not survive....

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#311 2018-12-29 14:48:39

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,741

Re: Going Solar...the best solution for Mars.

Up until recent we have had large solid panels, the atk fan and a flexible plastic substrate cell format but the work of nasa is pushing for a roll our array as well. I believe that the cell plate is not flexible but the fabric that its attached to is.

https://www.nasa.gov/offices/oct/home/feature_sas.html

https://www.nasa.gov/mission_pages/stat … /2139.html

The space test was done at the ISS using the canadian arm...

https://www.pv-magazine.com/2017/06/23/ … -in-space/

https://www.space.com/37250-roll-out-so … ation.html

The system uses a rail to extend the length of the array and a means to push it outward plus the roller that the array is wrapped on.

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#312 2018-12-29 15:21:02

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,741

Re: Going Solar...the best solution for Mars.

June of 2017 and silence about the test it would seem...

https://en.wikipedia.org/wiki/Roll_Out_Solar_Array

https://ntrs.nasa.gov/archive/nasa/casi … 005379.pdf

https://www2.jpl.nasa.gov/adv_tech/phot … ES1976.pdf

https://ntrs.nasa.gov/search.jsp?R=20130008777

The Flexible Array Concentrator Technology (FACT) is a lightweight, high-performance reflective concentrator blanket assembly that can be used on flexible solar array blankets

https://sbir.gsfc.nasa.gov/printpdf/31223
Materials and Structures Optimization / Process ... - NASA

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#313 2018-12-29 16:55:14

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,440

Re: Going Solar...the best solution for Mars.

Great news...looks like perfect timing for the Space X Mars Mission. smile

Would be interesting to see some figures for Earth orbit generation - Whs per sq metres per hour and per kg at peak in Earth orbit, so we can extrapolate to Mars.


SpaceNut wrote:

June of 2017 and silence about the test it would seem...

https://en.wikipedia.org/wiki/Roll_Out_Solar_Array

https://ntrs.nasa.gov/archive/nasa/casi … 005379.pdf

https://www2.jpl.nasa.gov/adv_tech/phot … ES1976.pdf

https://ntrs.nasa.gov/search.jsp?R=20130008777

The Flexible Array Concentrator Technology (FACT) is a lightweight, high-performance reflective concentrator blanket assembly that can be used on flexible solar array blankets

https://sbir.gsfc.nasa.gov/printpdf/31223
Materials and Structures Optimization / Process ... - NASA


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#314 2018-12-29 21:06:02

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,741

Re: Going Solar...the best solution for Mars.

Found why we did not hear much about this experiment...
Farewell, ROSA! Space Station Lets Go of Roll-Out Solar Array After Retraction Fail (Video)

After a week of tests on the end of the International Space Station's robotic arm, the Roll-Out Solar Array (ROSA) was safely jettisoned. While the rollable solar panel unfurled successfully at the beginning of the experiment, the ground operations team was unable to retract it to stow.

https://spaceflightnow.com/2017/06/30/p … trip-home/

ROSA was extracted with the station’s Canadian-built robotic arm and extended to a length of more than 15 feet (4.5 meters).

The solar array unfurled June 18, extending like a party favor with tensioning booms on both sides of the 5.5-foot-wide (1.6-meter-wide) wing.

Developed by Deployable Space Systems of Goleta, California, in partnership with the Air Force and NASA, the Roll-Out Solar Array tested solar cells capable of generating up to 300 watts of electricity. But future versions of the solar panel could extend to much greater lengths, producing as much as 500 kilowatts of power, according to Banik.

ROSA solves this problem by reducing mass by 20 percent and reducing stowed volume by 400 percent over these traditional approaches.”

1.6 x 4.5 = 7.2 m^2 for an output of 300w is horrible.... its 1300 w for each meter of input just 3% of what it could be doing....that has got to be a heat caused issue for how low the power output is....

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#315 2018-12-30 08:09:13

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,440

Re: Going Solar...the best solution for Mars.

I think that Spaceflightnow article must have got garbled somewhere along the line. No way can that figure be right.  It's probably the individual panel sections are generating 300ws peak. Or maybe it was 3000ws? 30% would be about right.

I've searched here there and everywhere but can't find any figures on power generation but I think it is safe to assume it's going to be around 30% of insolation. 

I think on Mars we could save on structure by either deployed directly on the ground (weighing down with rocks) or by rolling out PV film on lightweight wire structures stretched between poles.






SpaceNut wrote:

Found why we did not hear much about this experiment...
Farewell, ROSA! Space Station Lets Go of Roll-Out Solar Array After Retraction Fail (Video)

After a week of tests on the end of the International Space Station's robotic arm, the Roll-Out Solar Array (ROSA) was safely jettisoned. While the rollable solar panel unfurled successfully at the beginning of the experiment, the ground operations team was unable to retract it to stow.

https://spaceflightnow.com/2017/06/30/p … trip-home/

ROSA was extracted with the station’s Canadian-built robotic arm and extended to a length of more than 15 feet (4.5 meters).

The solar array unfurled June 18, extending like a party favor with tensioning booms on both sides of the 5.5-foot-wide (1.6-meter-wide) wing.

Developed by Deployable Space Systems of Goleta, California, in partnership with the Air Force and NASA, the Roll-Out Solar Array tested solar cells capable of generating up to 300 watts of electricity. But future versions of the solar panel could extend to much greater lengths, producing as much as 500 kilowatts of power, according to Banik.

ROSA solves this problem by reducing mass by 20 percent and reducing stowed volume by 400 percent over these traditional approaches.”

1.6 x 4.5 = 7.2 m^2 for an output of 300w is horrible.... its 1300 w for each meter of input just 3% of what it could be doing....that has got to be a heat caused issue for how low the power output is....


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#316 2018-12-30 11:06:37

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,741

Re: Going Solar...the best solution for Mars.

We have talked about the laying on the ground drops the amount that the array will produce as it needs to be perpendicular to the suns rays. Also now it will be dusted all the time and further reducing the level of out put between cleanings.

https://www.civicsolar.com/support/inst … rgy-output

The effect of an array's tilt angle on solar PV energy output may be up to 20% compared to that of flat installations. A comparison of data in two US cities has been completed to exhibit the importance of a solar PV arrray's tilt angle.

https://www.solarchoice.net.au/blog/fla … -vs-tilted

Small variations away from these ideals will not result in a significant difference in the power output of your solar energy system, which is why the natural tilt angle of your roof is usually fine (and keeping that tilt frames can add significantly to the cost of your system, putting a damper on the value of the solar power it produces).

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#317 2018-12-30 11:54:42

louis
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From: UK
Registered: 2008-03-24
Posts: 5,440

Re: Going Solar...the best solution for Mars.

I don't think you mean "perpendicular" Spacenut...looks like 30 degree tilt is optimal.  You could get that from a hillside. But of course that would then require your landing location to have convenient south facing hillsides within perhaps 1 km and laying out would be a bit of a struggle.  If you went with laying out, I think you would choose flat ground. Yes there is a loss, but in terms of mass carried to Mars then there is a plus side, given you minimise structure.

But I think my preferred method would be laying ultralightweight PV on wires strung between poles (rather like you get in a vinyard). That way you can get your 30 degree tilt.  The structure can be very lightweight as the weather on Mars presents no real problems - apart from the extreme temperature but that is a given for space-rated PV I would presume. Also, with PV film on wires, you can probably clear most dust simply by "twanging" the wires (vibration has proved very effective in getting rid of unwanted dust on robot missions, I understand). A robot rover could simply go up and down the line all sol long operating some twanging mechanism.

SpaceNut wrote:

We have talked about the laying on the ground drops the amount that the array will produce as it needs to be perpendicular to the suns rays. Also now it will be dusted all the time and further reducing the level of out put between cleanings.

https://www.civicsolar.com/support/inst … rgy-output

The effect of an array's tilt angle on solar PV energy output may be up to 20% compared to that of flat installations. A comparison of data in two US cities has been completed to exhibit the importance of a solar PV arrray's tilt angle.

https://www.solarchoice.net.au/blog/fla … -vs-tilted

Small variations away from these ideals will not result in a significant difference in the power output of your solar energy system, which is why the natural tilt angle of your roof is usually fine (and keeping that tilt frames can add significantly to the cost of your system, putting a damper on the value of the solar power it produces).


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#318 2018-12-30 20:23:24

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,741

Re: Going Solar...the best solution for Mars.

Ya perpendicular to the suns incoming rays....
th?id=OIP._6pAyVUeqkERh5zZhgb3UgHaF7&w=141&h=105&c=8&rs=1&qlt=90&pid=3.1&rm=2

u is the position of the sun relative to the face of the panel t

the angle is chosen from the definition of plum which intersects the right angle at the panel sun alignment point

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#319 2018-12-31 04:24:44

louis
Member
From: UK
Registered: 2008-03-24
Posts: 5,440

Re: Going Solar...the best solution for Mars.

Apologies SpaceNut! My misreading.

SpaceNut wrote:

Ya perpendicular to the suns incoming rays....
http://tse1.mm.bing.net/th?id=OIP._6pAy … d=3.1&rm=2

u is the position of the sun relative to the face of the panel t

the angle is chosen from the definition of plum which intersects the right angle at the panel sun alignment point


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#320 2018-12-31 09:29:35

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,741

Re: Going Solar...the best solution for Mars.

I can get things wrong.....and no worries as this is a good topic to know what we have researched and learned together as a group.
I do hope the ROSA cells did perform better than the article indicate efficiency as they would save mass for mars. Also like you indicated a few poles set in the ground with guide wire to support it would be as good as we can get for aligning them at the location required angle. Also by being flexible the angle can be altered as the season changes to keep the output as high as it can be even in winter....
With the aid of reflective materials to redirect the sun we can even think about boosting the output or the array as well.

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#321 2019-07-14 15:59:18

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,741

Re: Going Solar...the best solution for Mars.

Bumping for technology developement of which if its going to be solar only then this should be an important document if it have been linked here.

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#322 2019-12-15 16:53:20

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,741

Re: Going Solar...the best solution for Mars.

A while ago I went and brought 2 solar powered sensed lighting units. One has the standard solar cells in clear with LED light, with the other having a solar cell that is difused plastic with cob leds. The difused plastic versus the glass is inferior to amount of light from a charge but for the experiment testing we are looking at predictable light from chaging when both are in the same environment.

I have been placing them outside in the sunlight with the alignment to the sun and on days that is overcast raining horizontal or level. The time for a full day for each have been monitored over weeks for each trial with the results being somewhat disappointing for the light duration from a day of charge.

While the rainy difused light is longer the intensity of the light to charge results in less than an evening duration and is most of the time about 2 hours of light from either at the most. This is the effect of a mars dust filled sky where the light intensity is difused. But on days that are clear the time when level does improve by at least an hour more of duration of light. But its the aligning of the cells toward the sun giving the most time of duration again with an additional 2 or more hours over the level condition.

The clear unit results with the difused unit not doing so well
difused level days charge = 2hrs total run time of light output for charge
light not cloudy level = 3hrs
light aligned  = 6hrs or more

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#323 2019-12-21 17:33:19

tahanson43206
Member
Registered: 2018-04-27
Posts: 1,804

Re: Going Solar...the best solution for Mars.

For Louis re topic ...

Here is (or appears to be) good news about advances in fabrication of multi-spectrum solar cells.

https://www.yahoo.com/finance/news/did- … 00117.html

(th)

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#324 2019-12-21 19:44:08

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 17,741

Re: Going Solar...the best solution for Mars.

The materials are different in each layer which collect some of the energy from each range of color frequencies of the light passing through it. These are multi junction which we are using on mars rovers and landers. I have seen articles indicating that 8 layers would collect more energy but the added mass is what makes them not worth doing..

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#325 2019-12-26 11:39:19

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 17,741

Re: Going Solar...the best solution for Mars.

Articles on solar and storage here

https://www.motherearthnews.com/renewable-energy

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