shade the poles to slow or stop global warming with SPS

It occurs to me that if we build a large fleet of robotic light-sail
craft and have them fly close to L1 for the earth-sun orbital system.
You can place them such that each craft shades the area around the
earths summer polar region (north pole in dec-feb, south in june-aug).

At the same time they can collect solar energy and beam it back to
earth. This does double duty in that you reduce the heat load melting
the ice cap on Greenland or Antarctica and provides electricity.

If required the microwave beam providing electricity can be relayed
from a space station in earth orbit.

Comments?

"Alfred Montestruc" wrote in message
oups.com...

Comments?

In fact, the beneficial effect of slightly shading the Earth would be
dwarfed by the beneficial effect of all the fossil-fuel plants retired in
favor of the SPS energy.

Stated alternately, SPS would help reduce global warming whether it blocked
sunlight that would normally strike the Earth or not.

--


Regards,
Mike Combs
----------------------------------------------------------------------
Member of the National Non-sequitur Society. We may not make
much sense, but we do like pizza.

Mike Combs wrote:
"Alfred Montestruc" wrote in message
oups.com...

Comments?

In fact, the beneficial effect of slightly shading the Earth would be
dwarfed by the beneficial effect of all the fossil-fuel plants retired in
favor of the SPS energy.

I think it would better than double it. Most SPS would not shade the
earth at all. In this way you prevent solar gain heat from getting to
the place where it can do the most damage in melting ice caps, and at
the same time keep the poles colder which will tend to pump circulation
of both the sea and atmosphere more, at the same time as sending a
smaller amount of power as electricity to the earth (the heat losses
will mostly be in space).

The improvment is in that the heat gain from CO2 is global and in some
places not unwelcome, while the shading to help cooling is focused on
where you need it most.



Stated alternately, SPS would help reduce global warming whether it blocked
sunlight that would normally strike the Earth or not.

True, but focused shading of spots that you really need to keep cool to
stop sea levels from rising would be a good thing.

The nature of the sunlight hitting the Earth is such that I doubt you
could shade sufficiently, much of the light would 'wrap" around the
shade, and you still get indirect/diffused/reflected light coming in
there. It's way easier to bounce light into dark areas with an orbiting
mirror than to make an effective shade.

In article .com,
D. Orbitt wrote:
The nature of the sunlight hitting the Earth is such that I doubt you
could shade sufficiently, much of the light would 'wrap" around the
shade...

No, there's only a bit of diffraction, although you must consider the
finite angular size of the Sun.

Cutting down sunlight to avert global warming has been looked at in some
detail. It's a big project but it is not fundamentally unworkable.

...and you still get indirect/diffused/reflected light coming in...

None of that happens in space. (More precisely, very little.)
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

D. Orbitt wrote:
The nature of the sunlight hitting the Earth is such that I doubt you
could shade sufficiently, much of the light would 'wrap" around the
shade, and you still get indirect/diffused/reflected light coming in
there. It's way easier to bounce light into dark areas with an orbiting
mirror than to make an effective shade.

Simply because you can see the sun around the lightsail, does not mean
it has not reduced the light flux. Look at a lunar eclipse where the
earth shades out the moon.

http://commons.wikimedia.org/wiki/Ca...:Lunar_eclipse

The reddening of the moon long before the full eclipse is seen is due
to much of the sun being shaded even if you can see X% of the sun
still.

My point is that reducing the total solar heat flux on say Greenland by
perhaps 2% during the months of June July and August could make a
significant difference.

The problem is, are the use Earth's resources by man as fuel caused
most of the global warming? Or is global warming just a natural process
caused by the Earth itself?



As for the S.P.S. that are placed in the Sun-Earth L1 point (quite
stable, but not stable enough for long occupation).

They might not be suitable for a space based solar power collectors for
Earth's use, due to Earth's rotation, imagine all of the work needed to
be done just to get the power transmitter arrays and power receiver
arrays to connect with each others.

And also it might be hard to control these shades at shading at the
right place or even shade at all.

Then there's matter if these things are able to stop or drastically
slow the melting polar ices at all.



As for melting ices at the polars.

Well... It's due because the Earth is adjusting itself.

The problem is that... are melting ices at the polars bad?

I mean that... most of the shallow seas around the world were used to
be land. With them existing as seas, people can travel easily using
water.

And also the melting of the ices at the north pole will improve sea
traffic at the northern polar seas.

D. Orbitt wrote:
The nature of the sunlight hitting the Earth is such that I doubt you
could shade sufficiently, much of the light would 'wrap" around the
shade, and you still get indirect/diffused/reflected light coming in
there. It's way easier to bounce light into dark areas with an orbiting
mirror than to make an effective shade.

You're not looking to create complete drakness, just decrease the amount
of insolation, it would be counter productive to totally blot out the sun,
but if you cover 10% of it's apparent angualr area, you reduce the amount
of energy pouring into the earth.




John
--
Remove the dead poet to e-mail, tho CC'd posts are unwelcome.
Mean People Suck - It takes two deviations to get cool.
Ask me about joining the NRA.

wrote in message
ups.com...

As for the S.P.S. that are placed in the Sun-Earth L1 point (quite
stable, but not stable enough for long occupation).

And another problem is that we can't talk about any object at that location
shading any particular part of the globe. At that distance from the Earth,
objects will cast (partial) shadows bigger than the Earth.


--


Regards,
Mike Combs
----------------------------------------------------------------------
Member of the National Non-sequitur Society. We may not make
much sense, but we do like pizza.

Mike Combs wrote:
wrote in message
ups.com...

As for the S.P.S. that are placed in the Sun-Earth L1 point (quite
stable, but not stable enough for long occupation).

And another problem is that we can't talk about any object at that location
shading any particular part of the globe. At that distance from the Earth,
objects will cast (partial) shadows bigger than the Earth.

And this is a problem... Why?

When I'm in a forest, lots of light hits the ground, yet things are
cooler becuase there's certain amount of shade. You need not create
totality on the ground to achieve a reduction in input energy and sunlight
that would have missed the earth anyway is unimportant to the equation.



John
--
Remove the dead poet to e-mail, tho CC'd posts are unwelcome.
Mean People Suck - It takes two deviations to get cool.
Ask me about joining the NRA.