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I expect this kind of sunshade is inevitable now and that pressure is mounting to build it, and it is extremely fortunate that a capability has developed to bui

I expect this kind of sunshade is inevitable now and that pressure is mounting to build it, and it is extremely fortunate that a capability has developed to build it very affordably (for a global project) and rapidly (at a push - 1 year!). Its likely just a matter of years or decades before warming events and modelling generate enough rational alarm to empower a global body to take control of global and continental solar insolation levels. Many thousands of individual sunshades can tilt using low power gyros, even in hourly timeframes to alter exactly when and where shading is applied to Earths regions and live weather systems, and also use a long term light-sail effect to keep themselves appropriately positioned while floating through the orbit-ally unstable Lagrange region. Unfortunately even recognition of a capability to build such a thing will certainly reduce pressure to rapidly de-carbonize, even the acidification of the oceans is hailed as solvable now by putting vast but affordable quantities of mined olivine them. Human depredation, mis-consumption and mis-appreciation of natural systems (as well as each other) remain gravely destructive and tragic modern persuasions until the narrative is healed.

ncmncm 7y ago
Anything that could be achieved with a sunshade could be done thousands of times more cheaply by putting reflectors on roofs, on deserts, and on the sea surface. If you imagine putting that much reflector out would be too hard or too expensive, I guarantee lofting even a tiny fraction of it would be overwhelmingly more expensive and difficult.
- strainer 7y ago
  The physics work out very differently because a lot of different wavelengths, some invisible are absorbed by the atmosphere (co2 and other absorbers) before and after reflecting off the ground. Sunshade designs have been considered viable by expert reviews. Main obstacle has been considered the cost of launching them to L1 estimated at a few trillion dollars. Spacex superheavy system is predicted to shrink that to a few billion dollars - a week or some of the global military budget. It would also need much thicker reflecting material on the ground / at sea to cope with weathering, tearing and pollution. Space is mainly very empty, the shades can be made from surprisingly light materials, and as I described before, the whole thing can be controllable to react to weather events. On ground installations take time an effort to alter.
  - beerandt 7y ago
    It's still a net positive, and assuming shades are deployed, it would at least reduce the number required. Reflectors in on the ground also have the benefit of being controllable.
    - strainer 7y ago
      When solar arrays are located over water they do alot of cooling because without them water reflects very little. Deserts already reflect a great deal of sunlight. Temperate land absorbs a great deal but it is in great demand for agriculture, aforestation and the remaining wildlife. Reflectors in space should be controllable, the power and gyroscopes required to rotate them at a snails pace can be tiny, a small percentage of the mass of the attached shade.
      - beerandt 7y ago
        Mostly agree, but: 1) Solar isn't really cooling anything, it's just transferring the heat to the point of use through the grid. 2) There's a lot of square footage of pavement and rooftops before we need to seek out virgin land. 3)Adding any feature to a production of 16 trillion won't be trivial in cost or complexity. Anything besides passive steerage (akin to a solar-windsock) is going to sink the project, IMO. I suspect that once you start adding power, gyros, controls, communication, navigation, etc, it will be more economical/feasable to scale up the size of each deployable shade by 2+ orders of magnitude (4+ by area). Which isn't to say it would be feasible, just more feasible.
        strainer 7y ago
        Good point about solar just transferring the energy. Im not sure how practical it is to brighten so many constructed surfaces like pavements and roads it makes a big impact and is tolerable to live with. An estimate that only 2.7% of the worlds land is urbanised, and 2/3rds being ocean... increasing its albedo significantly could be difficult. An advantage of space shading is it doesn't rotate out of play and can be concentrated a bit away from the edges of the globe where light is a bit more likely to reflect away. Agreed it would be difficult and heavy to add minature gyroscopic and solar cell, comms and control unit to the 16 trillion disks proposal, since they are just 60cms wide. That plan seems basically like throwing confetti into L1, where it might get drifted away by solar ejections, out of stable orbit, in matter of years. Since each of those disks is 1 gram and about 0.25 square meters, that scheme involves total of 4 trillion square meter shades orientated randomly. If shades are squares for simplicity and 8 meters in diameter, so 64 meters square and similar material would be 256 grams, add some stiffening and a control unit for say an extra 150 grams. Maybe a clever unfolding feature like an insects wing. Its a bit more material to launch but probably less than double at some control/shade ratio, and the tracking shades will block light about 30% more effectively than randomly orientated ones. Works out around 50 billion of the 400gram 8 meter wide shades with mini solar-comms-gyro units to produce. So I'm still overconfident in the practically of this kind of scheme, especially since cost to space has been minaturised since they previously had expert attention. I have to admit its just one of those hunches Im hawking of late, cheers for following :)

ncmncm 7y ago

Anything that could be achieved with a sunshade could be done thousands of times more cheaply by putting reflectors on roofs, on deserts, and on the sea surface. If you imagine putting that much reflector out would be too hard or too expensive, I guarantee lofting even a tiny fraction of it would be overwhelmingly more expensive and difficult.

strainer 7y ago
The physics work out very differently because a lot of different wavelengths, some invisible are absorbed by the atmosphere (co2 and other absorbers) before and after reflecting off the ground. Sunshade designs have been considered viable by expert reviews. Main obstacle has been considered the cost of launching them to L1 estimated at a few trillion dollars. Spacex superheavy system is predicted to shrink that to a few billion dollars - a week or some of the global military budget. It would also need much thicker reflecting material on the ground / at sea to cope with weathering, tearing and pollution. Space is mainly very empty, the shades can be made from surprisingly light materials, and as I described before, the whole thing can be controllable to react to weather events. On ground installations take time an effort to alter.
- beerandt 7y ago
  It's still a net positive, and assuming shades are deployed, it would at least reduce the number required. Reflectors in on the ground also have the benefit of being controllable.
  - strainer 7y ago
    When solar arrays are located over water they do alot of cooling because without them water reflects very little. Deserts already reflect a great deal of sunlight. Temperate land absorbs a great deal but it is in great demand for agriculture, aforestation and the remaining wildlife. Reflectors in space should be controllable, the power and gyroscopes required to rotate them at a snails pace can be tiny, a small percentage of the mass of the attached shade.
    - beerandt 7y ago
      Mostly agree, but: 1) Solar isn't really cooling anything, it's just transferring the heat to the point of use through the grid. 2) There's a lot of square footage of pavement and rooftops before we need to seek out virgin land. 3)Adding any feature to a production of 16 trillion won't be trivial in cost or complexity. Anything besides passive steerage (akin to a solar-windsock) is going to sink the project, IMO. I suspect that once you start adding power, gyros, controls, communication, navigation, etc, it will be more economical/feasable to scale up the size of each deployable shade by 2+ orders of magnitude (4+ by area). Which isn't to say it would be feasible, just more feasible.
      - strainer 7y ago
        Good point about solar just transferring the energy. Im not sure how practical it is to brighten so many constructed surfaces like pavements and roads it makes a big impact and is tolerable to live with. An estimate that only 2.7% of the worlds land is urbanised, and 2/3rds being ocean... increasing its albedo significantly could be difficult. An advantage of space shading is it doesn't rotate out of play and can be concentrated a bit away from the edges of the globe where light is a bit more likely to reflect away. Agreed it would be difficult and heavy to add minature gyroscopic and solar cell, comms and control unit to the 16 trillion disks proposal, since they are just 60cms wide. That plan seems basically like throwing confetti into L1, where it might get drifted away by solar ejections, out of stable orbit, in matter of years. Since each of those disks is 1 gram and about 0.25 square meters, that scheme involves total of 4 trillion square meter shades orientated randomly. If shades are squares for simplicity and 8 meters in diameter, so 64 meters square and similar material would be 256 grams, add some stiffening and a control unit for say an extra 150 grams. Maybe a clever unfolding feature like an insects wing. Its a bit more material to launch but probably less than double at some control/shade ratio, and the tracking shades will block light about 30% more effectively than randomly orientated ones. Works out around 50 billion of the 400gram 8 meter wide shades with mini solar-comms-gyro units to produce. So I'm still overconfident in the practically of this kind of scheme, especially since cost to space has been minaturised since they previously had expert attention. I have to admit its just one of those hunches Im hawking of late, cheers for following :)