Shielding against the Sun with a large sheet of aluminum foil in Earth orbit?

[bob012345]

It would have to be a lot less than half. The radiative forcing that is contributing to current warming is only a fraction of a percent of the total radiation we get from the Sun.

SpaceX is putting up so many Starlink satellites that they may contribute to global cooling.

 

[sophiecentaur]

Pretty impressive idea for a sci fi story actually.

I would imagine that an author who thought about the problem from an Engineering or Political point of view would give the idea better scrutiny than as a Fun Space Plotline. I've read so many SciFi stories that hang on a very fine scientific thread that they border onto fantasy.

If one bad element got power of that "ring"

They (and also the good guys) would need the power of a selective on/off switch to target the times and latitudes of the shielding. World food supply is a vital issue (e.g. Ukraine's grain) and the real life performance of a shield would be very relevant to that. It would, in fact, be a massive experiment.

One should always ask what dear of Arthur C Clarke would have made of such an idea. As the idea has been submitted to PF then I would have thought that some technical rigour had been asked for, whatever the story lines of the characters.

 

[DaveC426913]

The ring is constructed by the powers on the earth.
As long as all those powers are aligned in the best interests of the planet. No malicious intent.
If one bad element got power of that "ring" I suppose the consequences could be bad.

Indeed. The One Ring might rule them all and in the darkness bind them.

 

[hmmm27]

Do the solar panels get less hot when the electricity is used?

Sure, though arguably, it all ends up as heat, eventually.

There was a firm touting a product that was an evacuated tube that used a PV element (also) as a thermal collector ; sounded decent for cold climates. I'd link, but the last time I visited they had stopped advertising it.

One I haven't seen (yet) is a PV system which passes chlorophyll spectrum EMF.

 

[sophiecentaur]

One I haven't seen (yet) is a PV system which passes chlorophyll spectrum EMF.

A new glass for greenhouses, perhaps. The holy grail for food production.

 

[hmmm27]

A new glass for greenhouses, perhaps. The holy grail for food production.

Perhaps, but in opposition to the pop-sci vision of "solar glass" building windows, a discrete assemblage including prismatic/mirror elements might be longer-lasting, allow for PV upgrades when available, and disallow the need for opaque PV elements.

 

[Algr]

- on Earth, the mirrors could be rigidly mounted and track the sun

For dissipating heat, this wouldn't be necessary. The mirrors could be permanently mounted facing up.

 

[Tiger Blood]

There is a new paper about shielding the sun. It proposes that 99% of shield material comes from the moon.

Here is the abstract:

This paper presents an approach to Solar Radiation Management (SRM) using a tethered solar shield at the modified gravitational L1 Lagrange point. Unlike previous proposals, which were constrained by the McInnes bound on shield surface density, our proposed configuration with a counterweight toward the Sun circumvents this limitation and potentially reduces the total mass by orders of magnitude. Furthermore, only 1% of the total weight must come from Earth, with ballast from lunar dust or asteroids serving as the remainder. This approach could lead to a significant cost reduction and potentially be more effective than previous space-based SRM strategies.

https://www.pnas.org/doi/10.1073/pnas.2307434120

 

[DaveC426913]

There is a new paper about shielding the sun. It proposes that 99% of shield material comes from the moon.

https://www.pnas.org/doi/10.1073/pnas.2307434120

What? No pics?

 

[hmmm27]

Does UV do anything useful ?

 

[DaveC426913]

Essential to creation of vitamin D..
Bacterial sterilizer...

 

[Tiger Blood]

What? No pics?
View attachment 330065

 

[Nik_2213]

I'm reminded of the picturesque Mediterranean islands etc whose towns & villages are widely white-washed / pink-washed to mitigate Summer sunshine. White is okay if you stay in shade, pink is probably better on the eyes, but photo-chromic polarised snow-glare goggles would seem advised...

Melting 'black-top' roads may become more of a problem, finding a non-glare binder that reflects infra-red problematic.

FWIW, we need some UV for our health: Trick is to acquire it in correct mix, strength and moderation...

 

[Strato Incendus]

Just out of curiosity and for context, what would happen to such a giant solar shield in the event of a solar flare?

I’ve also heard of concepts that act more like a rim with a lid that can be gradually opened, depending on how much sun you want to let through. Such a construction (again placed at the first Lagrange point) would probably be built out of a more robust material than a thin shield of aluminium. Nevertheless, the question remains of what a solar flare would do to such a construction.