5 ms·

This seems very inefficient due to the high energy cost and the long timescales in the proposal. The long timescales means it would be hard to adapt this method

by sxp 5y ago

This seems very inefficient due to the high energy cost and the long timescales in the proposal. The long timescales means it would be hard to adapt this method to counteract rapid weather & climate fluctuations. A better option to control climate due to the sun would be to build a https://en.wikipedia.org/wiki/Space_sunshade https://en.wikipedia.org/wiki/Space_sunshade between Earth and the Sun. While the common design is a monolithic piece of metal to block the sun, a more practical design would involve a swarm of reflective robots flying in the appropriate set of orbits. They would be powered by solar panels and maneuver using solar sails to constantly adjust their orbits. That would allow your to block as much sunlight as you want and adjust the levels on a daily basis. You could also divert sunlight rather than blocking it which means you could increase the amount of sun the Earth gets if you want more light. Or you could use the swarm to focus sunlight on a certain part of the Earth while blocking light to other parts. This would allow for localized climate modification or even weather modification if you had a powerful enough supercomputer to predict the chaotic effects. Since you could adjust the light distribution on the order of days rather than centuries, there would be a lot more room for fine-grained control compared to orbital modification.

montalbano 5y ago
> supercomputer to predict the chaotic effects. This might be the hardest part of your proposal to achieve. Chaotic systems are fundamentally difficult to simulate, not just because of their differential equations but our lack of perfect knowledge of their initial conditions. Blanket solar reduction seems more feasible?
pankajdoharey 5y ago
I believe, much before those timescales humans would have become a Type 2 or Type 3 civilisation.
- Retric 5y ago
  A sunshade is almost feasible using current technology, though it would have some negative impacts. Solar Cruiser is a 1,672 m2 solar sail being sent to L1 for 65 million. Which is of course nowhere close to cost effective for lowering global temperatures, but the basic components are there.
- sxp 5y ago
  In Accelerando [1], humanity becomes a Type II civilization and builds a Matrioshka swarm. But it shines sunlight on Earth by opening up a hole in the swarm so that the sun is visible to Earth. That would allow harnessing almost all of the Sun's energy but would let Earth remain as a stable nature preserve for nostalgia purposes. [1] http://www.antipope.org/charlie/blog-static/fiction/accelerando/accelerando-intro.html http://www.antipope.org/charlie/blog-static/fiction/accelera...
nonameiguess 5y ago
The Montgomery Burns plan. The Simpsons will have again predicted the future better than any science fiction writer could dream.
- alanbernstein 5y ago
  ...except that 1) it hasn't happened in the real world, 2) it was proposed in December 1989 (if not earlier), about the same time as the first episode of The Simpsons aired. https://ui.adsabs.harvard.edu/abs/1989JBIS...42..567E/abstract https://ui.adsabs.harvard.edu/abs/1989JBIS...42..567E/abstra...
  - marcellus23 5y ago
    “will have”
Voloskaya 5y ago
> This seems very inefficient due to the high energy cost and the long timescales in the proposal. This is efficient for what the paper is about: A solution to the sun's gradual evolution towards a red giant. So long timescale is not a problem, since we have 1B year before the sun becomes too hot for where we are today, and 5B years before being engulfed by it. Space sunshades works well to reduce incoming radiations by a few % (e.g. for current climate change problem), it won't work so well when the earth will be within the sun's corona.
- LorenPechtel 5y ago
  No--we have nowhere near a billion years. It's roughly a billion until all life is wiped from the planet, but it will be uninhabitable for humans *long* before that point. We have only 50 million years before Earth's ability to adapt to solar warming pegs and the temperature starts crawling up--and note that even that will not be good for an awful lot of plant life because of low CO2 levels. Earth needs to start it's retreat before then.
  - nextaccountic 5y ago
    > We have only 50 million years before Earth's ability to adapt to solar warming pegs and the temperature starts crawling up This sounds like an oddly small estimate. Life has been around 3.5 billions of years and has passed through multiple extinction events. It would be a puzzling coincidence that human civilization appears and then we have only some tens of million years to avert catastrophe.
    - kadoban 5y ago
      Doesn't necessarily sound like a bad estimate just based on approximate frequency of other extinction events. What they're describing doesn't necessarily sound like the end of life on Earth, only the end of life as we know it. I'm not following what the mechanism is supposed to be though.
      - LorenPechtel 5y ago
simonh 5y ago
Putting them in Earth orbit would allow for local variation, but would be much less efficient overall. Firstly because they would only be between the Earth and the sun for a very small fraction of their orbital period, and also because they would be so close to the earth they would only shade a relatively small multiple of the area of the satellites. This is why most proposals put the sun shade(s) in sun synchronous orbit between the earth and the sun. They would be a lot closer to the sun, and so intercept a lot more sunlight per area of satellite, and they would be blocking it all the time, or for as long as you wanted.
- kurthr 5y ago
  I think that's what the parent is referring to (from the wikipedia page they are in L1). Of course that does require the active orbital stabilization also described (though not as around L1). Being closer to the sun is a big advantage, but also impulse heavy to get there. Perhaps an initial lift up to an unshadowed low earth orbit could boot strap a solar ion/sail to get them to L1?
dtgriscom 5y ago
> you could use the swarm to focus sunlight on a certain part of the Earth Whenever I see a proposal like this (e.g. orbiting solar power stations beaming microwaves down to terrestrial receivers) I think "super-weapon." I can't see why country A would ever allow disliked country B to implement such a scheme.

by sxp 5y ago

montalbano 5y ago

> supercomputer to predict the chaotic effects. This might be the hardest part of your proposal to achieve. Chaotic systems are fundamentally difficult to simulate, not just because of their differential equations but our lack of perfect knowledge of their initial conditions. Blanket solar reduction seems more feasible?

pankajdoharey 5y ago

I believe, much before those timescales humans would have become a Type 2 or Type 3 civilisation.

Retric 5y ago
A sunshade is almost feasible using current technology, though it would have some negative impacts. Solar Cruiser is a 1,672 m2 solar sail being sent to L1 for 65 million. Which is of course nowhere close to cost effective for lowering global temperatures, but the basic components are there.
sxp 5y ago
In Accelerando [1], humanity becomes a Type II civilization and builds a Matrioshka swarm. But it shines sunlight on Earth by opening up a hole in the swarm so that the sun is visible to Earth. That would allow harnessing almost all of the Sun's energy but would let Earth remain as a stable nature preserve for nostalgia purposes. [1] http://www.antipope.org/charlie/blog-static/fiction/accelerando/accelerando-intro.html http://www.antipope.org/charlie/blog-static/fiction/accelera...

nonameiguess 5y ago

The Montgomery Burns plan. The Simpsons will have again predicted the future better than any science fiction writer could dream.

alanbernstein 5y ago
...except that 1) it hasn't happened in the real world, 2) it was proposed in December 1989 (if not earlier), about the same time as the first episode of The Simpsons aired. https://ui.adsabs.harvard.edu/abs/1989JBIS...42..567E/abstract https://ui.adsabs.harvard.edu/abs/1989JBIS...42..567E/abstra...
- marcellus23 5y ago
  “will have”

Voloskaya 5y ago

> This seems very inefficient due to the high energy cost and the long timescales in the proposal. This is efficient for what the paper is about: A solution to the sun's gradual evolution towards a red giant. So long timescale is not a problem, since we have 1B year before the sun becomes too hot for where we are today, and 5B years before being engulfed by it. Space sunshades works well to reduce incoming radiations by a few % (e.g. for current climate change problem), it won't work so well when the earth will be within the sun's corona.

LorenPechtel 5y ago
No--we have nowhere near a billion years. It's roughly a billion until all life is wiped from the planet, but it will be uninhabitable for humans *long* before that point. We have only 50 million years before Earth's ability to adapt to solar warming pegs and the temperature starts crawling up--and note that even that will not be good for an awful lot of plant life because of low CO2 levels. Earth needs to start it's retreat before then.
- nextaccountic 5y ago
  > We have only 50 million years before Earth's ability to adapt to solar warming pegs and the temperature starts crawling up This sounds like an oddly small estimate. Life has been around 3.5 billions of years and has passed through multiple extinction events. It would be a puzzling coincidence that human civilization appears and then we have only some tens of million years to avert catastrophe.
  - kadoban 5y ago
    Doesn't necessarily sound like a bad estimate just based on approximate frequency of other extinction events. What they're describing doesn't necessarily sound like the end of life on Earth, only the end of life as we know it. I'm not following what the mechanism is supposed to be though.
    - LorenPechtel 5y ago

simonh 5y ago

Putting them in Earth orbit would allow for local variation, but would be much less efficient overall. Firstly because they would only be between the Earth and the sun for a very small fraction of their orbital period, and also because they would be so close to the earth they would only shade a relatively small multiple of the area of the satellites. This is why most proposals put the sun shade(s) in sun synchronous orbit between the earth and the sun. They would be a lot closer to the sun, and so intercept a lot more sunlight per area of satellite, and they would be blocking it all the time, or for as long as you wanted.

kurthr 5y ago
I think that's what the parent is referring to (from the wikipedia page they are in L1). Of course that does require the active orbital stabilization also described (though not as around L1). Being closer to the sun is a big advantage, but also impulse heavy to get there. Perhaps an initial lift up to an unshadowed low earth orbit could boot strap a solar ion/sail to get them to L1?

dtgriscom 5y ago

> you could use the swarm to focus sunlight on a certain part of the Earth Whenever I see a proposal like this (e.g. orbiting solar power stations beaming microwaves down to terrestrial receivers) I think "super-weapon." I can't see why country A would ever allow disliked country B to implement such a scheme.