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## Solar shield idea to address climate change.

solar shield-s2.jpg

This solar shield would be positioned near L1.
To reduce the solar wind pressure by 10%, I think the solar wind pressure would be around 5 tonnes(Earth weight equivalent)..?

There would be a counter weight to this that would be closer to the sun than L1.

The sail would be made of some future possible material which was thin, and reflective, and would reflect the solar radiation away from their path towards the Earth.

The whole thing would be revolving, to keep the sails, in a circle, stretched out.

There would be springs between the orange and green sails, so when the solar wind increased, the pressure on the sails would increase, and so the springs would pull the sails inwards, and so show less surface area towards the sun, and so reduce the pressure on the whole thing causing, maybe the counterweight to drop further towards the sun and away from L1, which would lead to the counterweight experiencing more force towards the sun, to counter the added pressure from the solar wind.

I had originally made the diagram with sales of alternating colours because I thought that one sale could act as a break to the force that causes rotation, and the green sails act to cause rotation, being at a fixed angle, and the orange sail varying its angle towards the sun, based upon the more springs(not shown in diagram).

When the thing is spinning the forces that case rotation should match the forces that brake the rotation, causing the thing to rotate at a fixed rate.

Anyway I think the whole thing is more complex that I realised...

Maybe this set-up might work if designed in the right way.

To keep the solar shield in the proximity of L1 is a balancing act between solar wind, and gravity.

To counter the wind the shield should in this idea, collapse a bit, due to the wind itself, and the self regulating centrifugal forces of rotation, and the springs between the ends on the sails..

I don't know; could something like this work?

Obviously the counterweight hub would maybe have to step in at some point to correct the system, but with my idea, it would mostly be a self-regulating set-up, based upon the performance of the materials, and the design.

It's complex because of all the changing forces around L1, the changing forces of the solar wind, and the complexity needed of the materials..

Anyway....it's an idea, ain't it??

It kind of looks like a shuttlecock, doesn't it....maybe it would behave like one as well....balanced on the winds of the sun...

edit: ok I admit it; there's a spelling mistake in the title, it's not a typhoid.....
Last edited by WaxRubiks; 2019-Feb-01 at 07:50 PM.

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It's not a new idea, I am afraid: https://en.wikipedia.org/wiki/Space_...e_engineering)

The L1 idea dates from 1989 at least.

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4. James T. Early. Space-based solar shield to offset greenhouse effect. Journal of the British Interplanetary Society (Dec 1989) 42: 567-9.

The construction of a thin glass shield is proposed to offset the greenhouse effects caused by CO2 buildup in the earth's atmosphere. It is suggested that the shield could be built from lunar materials and should be located near the first Lagrange point of the earth-sun system. Consideration is given to the photon thrust of the shield, the shield size, effective blockage, and possibilities for shield design
Grant Hutchison

5. Wouldn't the decrease in sunlight also decrease photosynthesis, and thus decrease the amount of CO2 that is being removed from the atmosphere by plants?

And for as much as such a thing might cost, couldn't one just buy a lot of renewable energy technology, like photovoltaics and wind turbines?

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Originally Posted by Swift
Wouldn't the decrease in sunlight also decrease photosynthesis, and thus decrease the amount of CO2 that is being removed from the atmosphere by plants?

And for as much as such a thing might cost, couldn't one just buy a lot of renewable energy technology, like photovoltaics and wind turbines?
But plant uptake of CO2 is limited, and the Carbon in the cycle remains fixed over the long-term apart from laying down peat etc..

I know the solar shield isn't a new idea, but this shuttlecock, self regulating system might be new..?

edit: I did think some carbon sequestering technology might be developed at some point making the whole idea of a solar shield redundant, for climate change, although it could be used for the terraforming of Venus for example.

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I think I've got it...

This shuttlecock solar shield(SSS...3S.?) should be closer to the Earth than L1.

When the solar wind is lowest, the 3s will fall towards L1..(?), and when it is highest it will be pushed back....a bit...?

Would that work, if the cone stayed the same shape?

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Maybe the plan should just ditch L1 altogether.

Could a 3S(SSS) stay in a position to shadow Earth, away from the stronnger influence of L1?

maybe it would be a good design for a Solar-stationary satellite, for purposes other than reducing climate change...

Maybe it could make a good delivery system to travel around the solar system..!

Change the angle of the cone to fall or rise towards, and away from the Sun.....maybe not fast, but fast enough to transport stuff around the solar system...

edit: the Shuttlecock Solar Solar-System Ship...5S.....there's getting to be a lot of 'S's.....add Satellite, maybe..?
Last edited by WaxRubiks; 2019-Feb-01 at 08:45 PM.

9. I like it.

Twist the 'vanes' slightly and the solar wind, or the light pressure, would act as a spinning force. This would keep the 'shuttlecock' spinning, and therefore extended.

I'm not sure if solar wind would be much of a problem, except when the Sun has a mass ejection event. The solar wind is normally very weak, but a mass ejection from the Sun would flood the shield with charged particles.`

You could maybe have the counterweight on an extendable tether, so that you could drop it further towards the Sun when the wind gets too strong.

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Originally Posted by eburacum45
I like it.

Twist the 'vanes' slightly and the solar wind, or the light pressure, would act as a spinning force. This would keep the 'shuttlecock' spinning, and therefore extended.

I'm not sure if solar wind would be much of a problem, except when the Sun has a mass ejection event. The solar wind is normally very weak, but a mass ejection from the Sun would flood the shield with charged particles.`

You could maybe have the counterweight on an extendable tether, so that you could drop it further towards the Sun when the wind gets too strong.

But in a vacuum there isn't anything to act like air friction, so it could just carry on increasing it's spin speed, without some kind of brake, you just need to be able to tilt the sails both ways, to regulate rotation rates..

Which maybe how it could be used as a transport vehicle to take stuff around the solar system.

11. If it helps with the greenhouse/climate change effects of CO2 that still leaves other unresolved problems such as acidification of the oceans. I read some time ago about an idea to dump lime into the worlds oceans to solve that problem. The prospect of getting the atmospheric CO2 level back below 400ppm seems dim now even if we halted burning fossil fuels today. Keep your plans handy ;-)

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6S sounds a bit like .....'success'...

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Originally Posted by WaxRubiks
6S sounds a bit like .....'success'...
perhaps we can get to 10S, and then we'll have 'tennis'....anyone for tennis..?

14. You're talking about a structure on a planetary scale, which you're nevertheless manipulating as if it were made of rigid parts (twisting the vanes, opening and closing the inclination angle). How do you achieve this rigid behaviour?

Grant Hutchison

15. Report out this week suggests the reforestation of inca lands when european invasion killed so many off, lowered CO2 and maybe caused the little ice age. Ice core data supports the idea although volcanoes maybe did the job too. But CO2 levels were lower then anyway.

16. Originally Posted by Shaula
It's not a new idea, I am afraid: https://en.wikipedia.org/wiki/Space_...e_engineering)

The L1 idea dates from 1989 at least.
New Earths by James Oberg (copyright 1981) had the idea of parasols to block sunlight for Venus terraforming, but there was almost no detail in the book, and an illustrations suggested multiple parasols in orbit. The book also mentions using dust, perhaps in a ring or other configurations. That said, James Early might have done the first serious analysis for Earth in 1989, but my memory is that the basic idea of an L1 sun shield was kicking around (as speculation at least) substantially before 1989.

17. Originally Posted by grant hutchison
You're talking about a structure on a planetary scale, which you're nevertheless manipulating as if it were made of rigid parts (twisting the vanes, opening and closing the inclination angle). How do you achieve this rigid behaviour?

Grant Hutchison
I would think more in line of a spoked tensile structure (not rigid), very slowly rotating, with thousands (or perhaps millions) of attached solar sails that could be angled to provide thrust for adjusting rotation and orbit of the structure.

Though it might be more feasible to have many completely separate sun shades, each with their own adjustable sails, instead.

18. I should add, for Earth, you'd only want to block a small fraction of the sunlight, so if it were a single structure, it would be mostly open.

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Originally Posted by grant hutchison
You're talking about a structure on a planetary scale, which you're nevertheless manipulating as if it were made of rigid parts (twisting the vanes, opening and closing the inclination angle). How do you achieve this rigid behaviour?

Grant Hutchison
the rigidity would be tensile based due to the centripetal forces within the revolving shield.

I imagine some future material what acts like a spring, over large distances.

To address climate change, I just read that you need to bock out 8% of the sun's radiation(call it 10%).

And so if you had a thousand of these cone shields then their radius need only be around 50km....not sure if the technology exists for even that size at the moment.
There would need to be rigid, and spring-like cables that could span that order of size, plus the actual shield surface material, which would be large thin sheets that were reflective, and strong.

With the cone system, their response to solar wind should be mainly self regulating, and maybe easily steerable by an onboard computer....

I'm wondering how they could be steered...maybe a second cone behind, set inside the main cone, and that didn't revolve, and could be made to point in different directions, in order to turn the whole thing into different orientations....a sort of rudder cone.

This Is how it might look:

solar shield cone ship.-s.jpg

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maybe my shuttlecock idea is unnecessarily complicated, and a simple parachute type design would work better.
Still not sure about whether it should revolve.

In this one there are 4 holes, which would have controllable flaps that could be pulled open and closed, to spill solar wind in one direction or another, to control the position on the shield vessel.

If the thing revolved, it would make controlling the direction difficult.

Solar sale shield.jpg

21. Originally Posted by WaxRubiks
the rigidity would be tensile based due to the centripetal forces within the revolving shield.
Well, no, because you're subjecting this thing to multiple forces - dealing with variable pressure from solar wind, tilting vanes, pointing different parts in different directions. You've got a gyroscopic effect to deal with, because the whole thing needs to rotate to stay facing the Earth as the Earth moves around the sun. So somehow all these forces need to be transmitted to the necessary distant parts, all these parts need to be held in an orientation that transmits force to the rest of the structure, and the resultant forces need to be transmitted uniformly, all without inducing oscillations. You can't just twist these things around like rigid plates, especially if you're stiffening them by rotation.
Your parachute is a much more realistic structure for what is, essentially, a solar sail.

Grant Hutchison

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yea, my original plan looks a bit Heath Robinson now...

It might be good idea, if the solar sail did still have the ability to rotate, as that should force the sail to expand giving the whole thing lift, away from the sun, if need be.
Perhaps it could have some side fins to achieve that.

The solar wind pressure I read is around 1-6 nN/m2....it's not that much...the sail sheet would have to be pretty low density material.

23. You'd do several orders of magnitude better from photon pressure - the solar wind is trivial by comparison.
But that's why you put your sail at L1 - very small station-keeping forces.

Grant Hutchison

24. I'd be less concrened about the engineering of the contraption than whether it will work in principle.

i.e. whether lowering insolation would limit photosynthesis and shorten growing seasons and such.

Would it be useful to limit it only certain wavelengths of solar radiation?
What wavelengths might leave crop-growing unaffected, yet reduce the particular wavelengths that contribute most to heat retention?

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Originally Posted by Swift
Wouldn't the decrease in sunlight also decrease photosynthesis, and thus decrease the amount of CO2 that is being removed from the atmosphere by plants?

And for as much as such a thing might cost, couldn't one just buy a lot of renewable energy technology, like photovoltaics and wind turbines?
Those have downsides on their own. SPSS/sunshades don't need bulldozers in the desert to build ground based solar. The back sides of such sunshades could be reflective--so if we have dimming, we can reflect more light to Earth... If the shadows focus more over water than land--the insolation budget changes but plants still get the light they need, or so I would think.

26. Originally Posted by publiusr
Those have downsides on their own. SPSS/sunshades don't need bulldozers in the desert to build ground based solar. The back sides of such sunshades could be reflective--so if we have dimming, we can reflect more light to Earth... If the shadows focus more over water than land--the insolation budget changes but plants still get the light they need, or so I would think.
More photosynthesis happens in the oceans than on land, so I don't think your last point is correct.

And of course, everything has a downside. The question is cost/benefit analysis and current availability of technology. Photovoltaics and wind turbines are established technology.

27. Originally Posted by Swift
Wouldn't the decrease in sunlight also decrease photosynthesis, and thus decrease the amount of CO2 that is being removed from the atmosphere by plants?

And for as much as such a thing might cost, couldn't one just buy a lot of renewable energy technology, like photovoltaics and wind turbines?
It probably is not a straightforward relationship. Many (most?) plants will produce more chlorophyll in lower light conditions. For example, SOP for nurseries is to cycle green plants through a period of shade as final preparation for sale because it causes them to become more green. Obviously there are limits but it is possible that up to some threshold reducing sunlight wouldn't cause a significant change in the rate plants remove CO2 from the atmosphere. Of course, even if that is the case there is still the question of whether or not the amount of decrease possible before impacting CO2 removal by plants would be of any significant benefit?

28. I expect you will have seen references to improved photosynthesis and the hope of making more effective plants. It seems to goal is food production but removing CO2 is also possible. A small change in a large area or land or sea would make a big difference to the balance, but for sure there would be, or will be unforseen consequences.

29. One thing that has gone completely unmentioned in this thread is the geopolitics. I won't advocate any particular position, so as to keep within CQ rules, but in the real world, this is going to be an issue. It is inconceivable to me that there will not be nations that will be concerned about any sort of global geoengineering projects, whether it is orbital solar shields, or scattering SO3 in the upper atmosphere, or adding iron to the oceans to kick up microorganism growth (so as to absorb more CO2), particularly if individual countries or groups of countries undertake these projects without getting "their" approval. And maybe they should be concerned. If I have the ability to block the sun over parts of the Earth, is that a potential weapon?

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Some poorer countries wanted to sue over satellite fly-overs, but to no effect
https://www.quora.com/Is-it-legal-fo...-take-pictures

If only the Sahara were along the equator....

31. Originally Posted by WaxRubiks
6S sounds a bit like .....'success'...
Or, the 6 looks like a b. A fine line, I guess.
Originally Posted by WaxRubiks
the rigidity would be tensile based due to the centripetal forces within the revolving shield.

I imagine some future material what acts like a spring, over large distances.

To address climate change, I just read that you need to bock out 8% of the sun's radiation(call it 10%).

And so if you had a thousand of these cone shields then their radius need only be around 50km....not sure if the technology exists for even that size at the moment.
50km in radius is pretty big! Not sure what current technology would handle that.

Let's see, L1 is 1/100 AU away, at that distance a 50km radius disk covers (50x100/700,000)2 of the sun's image in the sky, so yeah you'd need about a thousand of them to cover 10%. Make'em 70km.

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