The number of launches needed to colonize the Red Planet is enough to orbit a sunshade that can save Earth from climate change. Why is this even a choice?
This isn't related to the post directly, but I just wanted to give a shout out to Karl's novel, STEALING WORLDS. I've got about 25 pages to go and I am REALLY enjoying it. It's both thought provoking and a great read.
I like the image of thousands of shades setting sail from LEO to L1, though I wonder if there might br traffic jams. Seriously though, there is one additional problem you didn't mention: L1 really isn't stable, it will require the sails to correct position and velocity, probably fairly often since they'll be filling up a volume that gets increasingly unstable toward its edges. If we assume the diffractive shade we'll need some additional engineering (read payload mass) to allow maneuvering with solar light pressure. We could use correction thrusters, but this sets a limit on the useful lifetime of a shade based on how long it takes to use up the propellant. So a part of the shade would probably have be used as a sail, requiring additional maneuvering to correct for light pressure or additional mass for a means of folding up the sail part of the shade.
Several papers go into great detail about these issues. It's well understood that L1 is not stable. One great advantage of using solar sails is that they don't need to be refueled, so they can maneuver until they finally break down. In practice, they'll orbit around L1 rather than remaining stationary there. And though collectively they'll block sunlight like a solid body, in their actual positions they'll be thousands of kilometers away from one another.
I have a concern about the greenhouse gas emissions from 80K launches. Assuming 5,000 tons of propellant per launch, we get 400 million tons of CO2 and H2O plus 4 million tons of methane (assuming 99 percent efficiency in the Raptor engines). That's about three quarters of Canada's carbon emissions in 2023. I wonder if we might be better off building solar power satellites instead. That would let us reduce fossil fuel consumption directly.
Best strategy is to build the sails on the moon and launch then from there using mass drivers. If we want speed, though (we do) then direct launches from Earth are best. The shade offsets the greenhouse effect from those 400 million tonnes, which are essentially a one-time insult. Ocean acidification is the chief environmental result and that is a problem, but now one we can deal with in isolation from climate change. --Also, switching fuels to hydrogen/oxygen is an obvious solution. --Now, all that said, it seens likely that there is a maximum daily launch rate that Earth's upper atmosphere and ionosphere can sustain. At some point I'll write about this potential choke point in our ambitions.
Hydrogen/Oxygen won't solve the greenhouse gas problem; water is a greenhouse gas in the upper atmosphere as we found out in the Tonga eruption a few years ago. The advantage of solar power satellites is we can use the power immediately to start reducing fossil fuel use. Maybe we could do both sun shades and SPS. Launching from mass drivers on the moon is a good idea, assuming that you can get the infrastructure up there in the first place and then have the materials to produce them.
Yes, please do a post on the effects of launches on the atmosphere. I've seen some recent articles suggesting that it could be a bigger problem than we thought, especially when coupled with the pollution from re-entering satellites and booster stages.
I’m deeply engaged in the environmental and climate space, yet I had never come across the orbital sunshade solution until now. That really highlights how little political will or public discourse exists around truly scalable interventions. This is an eye-opening, well-argued article. Thanks for writing it.
It’s an intriguing idea. I don’t think it would change the apparent fact of the upcoming magnetic pole shift sometime in the next 25 years. Or less. There seems to be mounting evidence but no action from governments. Maybe the Musk-man knows something we don’t? As a futurist, has pole shift come up in the discussions?
Like most "giant leap" projects, the engineering is the easiest part of the challenge. The big ones for Musk's Mars Project is "Who pays for it?" and "Who gets the benefits?". Solar shields have both those questions and others, like "who is liable for shade-induced weather damage?" or those who stand to benefit from some warming wanting to stop the project (opening of Arctic Passage, opening up tundra regions for development, etc.). Building the political case should be easy, but isn't because of both cost and entrenched conflicting interests. A Golden or Silver Age SF writer writing it as a story would have had the heroic world's first Trillionaire do it as secret project thus demonstrating both their heroic self sacrifice and superior intellect. If we could not get those in power to take steps to reverse course on greenhouse gas emissions when we had time, how do we persuade them to act now for mitigation only? The hard part is always people
We are primarily interested in reducing the conversion of solar radiation to IR that gets trapped by GHG. This conversion is due to the absorption of sunlight and is reradiated at IR. So why not reflect the radiation at any point before it reaches the ground?
The sunshades could be balloons with silvered surfaces in the high stratosphere, or sheets of reflective material on the surface, like super-scale Christo artworks. The ideal placement is over the oceans at the equator, where the albedo is low. The deep oceans have low primary productivity, so floating rafts of reflective material would not cause a huge depletion of algal photosynthesis and carbon fixation. Balloons in the startosphere would have a harder time to maintain station keeping, but Google's discontinued Loon project demonstrated it is possible to navigate using different wind directions with altitube.
Yes, surface and floating sunshades would likely require more maintenance and upkeep, but they may be far cheaper overall, and not require costly deployment with rockets. Should air capture methods prove more effective in the future, they will be easier to remove in stages. Keeping them on or over the oceans, they will neither disrupt commerce nor astronomical and communication systems. For 100% reflective surfaces, you need a area 2000x2000 km, easily small enough to be put into the various oceans - Pacific, Atlantic, Indian to convert much of the reflection needed over 24 hours. The coverage need not be contiguous, but spackled everywhere, to provide the needed 2% reduction of sunlight reaching the surface.
While more expensive than sulfur clouds, they do not add to acid rain, although they might cause more plastic pollution. Tradeoffs.
It's definitely possible. The specific term for such an object is "aerostat" and they've been tested at high altitudes to hang about for weeks at a time. It's cold enough in the stratosphere that CO2 could be formed as frost on thin sheets hung from them, then dropped to collectors on the ground... Nonetheless, to do this at scale would involve a massive industrial infrastructure be created. What attracts me to the orbital shade is that once it's in place, you just need a few yearly launches to replace failing sails. The point is to do as little as possible to/in the Earthly environment. Ideally, by the end of the project the sails are being manufactured and launched from the moon, so the effort has zero impact at home.
OTOH, it would be as well to pilot a smaller sunshade in space to determine if it has any useful effect at all. Sunshades in geosync positioned over specific locations - the Pacific, the Sahara, etc. would be able to provide information on the radiative changes that would be useful in understanding effects, placement, and indicative of a full statite sunshade in space. [yes I know that geosync would require sunshades to cover 12 hours of sunlight over an area which would be less effective than a statite whose effect would create a moving shade like an eclipse, but require less mass.]
But while sunshades in space are an expensive fix, I have to wonder if just painting roofs very white, and covering some roads and sidewalks in cities with reflective shades wouldn't be a simpler, cheaper solution to have the same effect. Add in tree planting as carbon sinks, curtailing CO2 emissions from various sources, especially cement manufacture, in total might be sufficient. I think something like this has been calculated. Apart from the effect of heating, I am very concerned about the acidification of the oceans. Changing the buffer equilibrium to increase the pH is not going to be trivial, yet if we don't do anything, we are going to lose a lot of ocean biodiversity. I don't want to see the oceans end up with a loss of species like the Permian-Triassic extinction.
Our current capitalist model has become like the "paperclip maximizer" AI thought experiment.
If we do decide to use reusable heavy lift rockets in huge numbers to deploy a sunshade, please find some viable way not to hand the program to Elon Musk or other oligarchs. ;-(
This isn't related to the post directly, but I just wanted to give a shout out to Karl's novel, STEALING WORLDS. I've got about 25 pages to go and I am REALLY enjoying it. It's both thought provoking and a great read.
I like the image of thousands of shades setting sail from LEO to L1, though I wonder if there might br traffic jams. Seriously though, there is one additional problem you didn't mention: L1 really isn't stable, it will require the sails to correct position and velocity, probably fairly often since they'll be filling up a volume that gets increasingly unstable toward its edges. If we assume the diffractive shade we'll need some additional engineering (read payload mass) to allow maneuvering with solar light pressure. We could use correction thrusters, but this sets a limit on the useful lifetime of a shade based on how long it takes to use up the propellant. So a part of the shade would probably have be used as a sail, requiring additional maneuvering to correct for light pressure or additional mass for a means of folding up the sail part of the shade.
Several papers go into great detail about these issues. It's well understood that L1 is not stable. One great advantage of using solar sails is that they don't need to be refueled, so they can maneuver until they finally break down. In practice, they'll orbit around L1 rather than remaining stationary there. And though collectively they'll block sunlight like a solid body, in their actual positions they'll be thousands of kilometers away from one another.
I have a concern about the greenhouse gas emissions from 80K launches. Assuming 5,000 tons of propellant per launch, we get 400 million tons of CO2 and H2O plus 4 million tons of methane (assuming 99 percent efficiency in the Raptor engines). That's about three quarters of Canada's carbon emissions in 2023. I wonder if we might be better off building solar power satellites instead. That would let us reduce fossil fuel consumption directly.
Best strategy is to build the sails on the moon and launch then from there using mass drivers. If we want speed, though (we do) then direct launches from Earth are best. The shade offsets the greenhouse effect from those 400 million tonnes, which are essentially a one-time insult. Ocean acidification is the chief environmental result and that is a problem, but now one we can deal with in isolation from climate change. --Also, switching fuels to hydrogen/oxygen is an obvious solution. --Now, all that said, it seens likely that there is a maximum daily launch rate that Earth's upper atmosphere and ionosphere can sustain. At some point I'll write about this potential choke point in our ambitions.
Hydrogen/Oxygen won't solve the greenhouse gas problem; water is a greenhouse gas in the upper atmosphere as we found out in the Tonga eruption a few years ago. The advantage of solar power satellites is we can use the power immediately to start reducing fossil fuel use. Maybe we could do both sun shades and SPS. Launching from mass drivers on the moon is a good idea, assuming that you can get the infrastructure up there in the first place and then have the materials to produce them.
Yes, please do a post on the effects of launches on the atmosphere. I've seen some recent articles suggesting that it could be a bigger problem than we thought, especially when coupled with the pollution from re-entering satellites and booster stages.
I’m deeply engaged in the environmental and climate space, yet I had never come across the orbital sunshade solution until now. That really highlights how little political will or public discourse exists around truly scalable interventions. This is an eye-opening, well-argued article. Thanks for writing it.
Superb post. I like the decision you pose and the models you built of the two options.
I do wonder about the political and cultural supports needed for the sunshade.
It’s an intriguing idea. I don’t think it would change the apparent fact of the upcoming magnetic pole shift sometime in the next 25 years. Or less. There seems to be mounting evidence but no action from governments. Maybe the Musk-man knows something we don’t? As a futurist, has pole shift come up in the discussions?
Like most "giant leap" projects, the engineering is the easiest part of the challenge. The big ones for Musk's Mars Project is "Who pays for it?" and "Who gets the benefits?". Solar shields have both those questions and others, like "who is liable for shade-induced weather damage?" or those who stand to benefit from some warming wanting to stop the project (opening of Arctic Passage, opening up tundra regions for development, etc.). Building the political case should be easy, but isn't because of both cost and entrenched conflicting interests. A Golden or Silver Age SF writer writing it as a story would have had the heroic world's first Trillionaire do it as secret project thus demonstrating both their heroic self sacrifice and superior intellect. If we could not get those in power to take steps to reverse course on greenhouse gas emissions when we had time, how do we persuade them to act now for mitigation only? The hard part is always people
Take all these considerations and subtract the trillionaire, and you have the background for my new novel. Because yes, the politics is the hard part.
Outstanding! I look forward to it.
Does the sunshade need to be in space?
We are primarily interested in reducing the conversion of solar radiation to IR that gets trapped by GHG. This conversion is due to the absorption of sunlight and is reradiated at IR. So why not reflect the radiation at any point before it reaches the ground?
The sunshades could be balloons with silvered surfaces in the high stratosphere, or sheets of reflective material on the surface, like super-scale Christo artworks. The ideal placement is over the oceans at the equator, where the albedo is low. The deep oceans have low primary productivity, so floating rafts of reflective material would not cause a huge depletion of algal photosynthesis and carbon fixation. Balloons in the startosphere would have a harder time to maintain station keeping, but Google's discontinued Loon project demonstrated it is possible to navigate using different wind directions with altitube.
Yes, surface and floating sunshades would likely require more maintenance and upkeep, but they may be far cheaper overall, and not require costly deployment with rockets. Should air capture methods prove more effective in the future, they will be easier to remove in stages. Keeping them on or over the oceans, they will neither disrupt commerce nor astronomical and communication systems. For 100% reflective surfaces, you need a area 2000x2000 km, easily small enough to be put into the various oceans - Pacific, Atlantic, Indian to convert much of the reflection needed over 24 hours. The coverage need not be contiguous, but spackled everywhere, to provide the needed 2% reduction of sunlight reaching the surface.
While more expensive than sulfur clouds, they do not add to acid rain, although they might cause more plastic pollution. Tradeoffs.
It's definitely possible. The specific term for such an object is "aerostat" and they've been tested at high altitudes to hang about for weeks at a time. It's cold enough in the stratosphere that CO2 could be formed as frost on thin sheets hung from them, then dropped to collectors on the ground... Nonetheless, to do this at scale would involve a massive industrial infrastructure be created. What attracts me to the orbital shade is that once it's in place, you just need a few yearly launches to replace failing sails. The point is to do as little as possible to/in the Earthly environment. Ideally, by the end of the project the sails are being manufactured and launched from the moon, so the effort has zero impact at home.
But you know, the most likely thing is that we do all these things, none at full scale.
OTOH, it would be as well to pilot a smaller sunshade in space to determine if it has any useful effect at all. Sunshades in geosync positioned over specific locations - the Pacific, the Sahara, etc. would be able to provide information on the radiative changes that would be useful in understanding effects, placement, and indicative of a full statite sunshade in space. [yes I know that geosync would require sunshades to cover 12 hours of sunlight over an area which would be less effective than a statite whose effect would create a moving shade like an eclipse, but require less mass.]
But while sunshades in space are an expensive fix, I have to wonder if just painting roofs very white, and covering some roads and sidewalks in cities with reflective shades wouldn't be a simpler, cheaper solution to have the same effect. Add in tree planting as carbon sinks, curtailing CO2 emissions from various sources, especially cement manufacture, in total might be sufficient. I think something like this has been calculated. Apart from the effect of heating, I am very concerned about the acidification of the oceans. Changing the buffer equilibrium to increase the pH is not going to be trivial, yet if we don't do anything, we are going to lose a lot of ocean biodiversity. I don't want to see the oceans end up with a loss of species like the Permian-Triassic extinction.
Our current capitalist model has become like the "paperclip maximizer" AI thought experiment.
If we do decide to use reusable heavy lift rockets in huge numbers to deploy a sunshade, please find some viable way not to hand the program to Elon Musk or other oligarchs. ;-(