They propose steering a very large rock around the solar system to transfer momentum from Jupiter to Earth. The point is to increase the orbit of Earth to accommodate the brightening of the Sun over the next 10^9 years. So it's a long term global warming mitigation project.
If the rock is big enough to do the job, the tides, earthquakes and volcanism around perigee could be inconvenient. Also, the power to set the gimbals on the rock is the power to extinguish the planet, and what organization could stay incorruptible for 10^9 years?
That was my first reaction as well: let's start mucking with earth's orbit, what could possibly go wrong? But the problem statement is trying to avoid being incinerated when the sun goes red-giant in a few billion years, so doing nothing is clearly not a viable alternative here.
On the other hand, given our current blase response to climate change, I'll give you long odds against human civilization being around in a billion years, or even a million -- or, for that matter, a thousand. And unless something changes radically in the next few years, I'll give you even odds against it lasting to the end of this century.
I can't see how we'd call any descendants of ours 'human' in a billion (or even a million) years, but I would be surprised if modern humans were wiped out in the next thousand years - we've lasted tens of thousands up to now. We certainly need to make some changes, but I'm at least semi-optimistic we can do that.
Humans have thrived in a wider range of ecosystems and environments than any other mammal I know of. Humans have did this without a global industrial base using only local technology and economic output.
Actually, I would be amazed if "humans" exist at that point. I wouldn't be surprised if they don't exist in even a thousand years.
Assuming we don't do ourselves in there will be sentients, but species are defined by the ability to interbreed and I expect genetic modification will reach the point that interbreeding with a stock human is no longer possible. At that point we will be a new species, not "human".
It is not global warming mitigation. This method has no hope of counteracting any kind of change in climate even on geological timescales. The only thing it can do is to slowly move Earth away from Sun over billions of years in imperceptible increments roughly every 6 thousand years.
I hope humanity can even survive 6 thousand years.
Irrelevant in context. Priesthoods in the examples above are just structures to preserve and transmit the knowledge of their respective missions to future generations. However corrupted are real religions it can't be denied that they've been running under the same traditions and knowledge corpus for millennia, and that's the point.
12000 years from now, Cockbert Roachstein, upon examining the peculiar dynamics of a passing moonlet, sets the scientific and philosophical community clicking and chirping with controversy on the suggestion that a mysterious ancient intelligence designed the scheme keep the planet's temperature in equilibrium as the sun heats up...
"You mean to suggest a bunch of *click* _monkeys_ could steer the planet? Those creatures-in-the-dust who couldn't even survive _radiation_? You are hereby sentenced for *chirp* roach-heresy."
Combining the odds of us developing much better mitigation techniques if we survive the next million years with the odds of fucking this up and either ruining the moon's orbit or smashing the rock into the earth, this is an unbelievably bad idea.
This *is* a mitigation technique for being swallowed by the sun--if we stay far enough away not to get too warm we also stay far enough away not to burn.
This is so backwards-looking. Why on Earth would you go to all this trouble to preserve a planet intact, when with comparable* effort you could dismantle it entirely and create orders of magnitude more habitable ecology in the form of free-floating O'Neill cylinders?
*(The solar gravity well is ~12 km/s deep and the Earth's gravity well is ~11 km/s, so dismantling the Earth and ejecting it are ~similar)
Effectively turning 2 class A white stars, 8 times as bright as Sol into computers, power plants and fuel for them, good for the next 14 trillion years:
"Power spheres take the place of the more commonly used central star of most solar systems, but are far more efficient. The average Sol-type sun will convert only a tiny fraction of its total mass into energy in the course of a lifetime of approximately 10 billion years. The Power Sphere network of Turing is designed to provide an amount of energy equal to that of a sun but for a period of more than 14 trillion years."
Or if you need more juice, say 100000x the output of the sun, you could sustain that for about 140 millions of years. ;-)
Well, eventually you might be even able to fixup the sun itself into a more favorable configuration for us with some solar lifting.
If you are crazy enough, you might even dismantle the sun outright and store the material as (predominantly) huge hydrogen icebergs you can burn in nice efficient fusion plants for the rest of eternity. Much more efficient! :)
Still much more difficult proposition that turning a terrestrial planet into an orbital swarm.
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 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.
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?
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.
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.
> 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.
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.
> 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.
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.
Mechanism: To keep the Earth cool the greenhouse effect needs to be turned down. That happens by CO2 being absorbed by water and turning into limestone. This is countered by limestone weathering and limestone getting sucked into volcanoes.
Over the eons the sun has grown warmer and Earth's CO2 levels have dropped, keeping the overall temperature pretty much stable. (There have been fluctuations in both directions that were major extinction events, though.)
Warming increases the rate CO2 gets converted into limestone, thus lowering the temperature. 50 million years is when that pegs and the mercury starts rising.
As for it being a puzzling coincidence--it might not be a coincidence at all. Think of the Fermi Paradox--where are the aliens? These days the astronomers tell us planets are very common. A look at the emergence of life on Earth says it happened about as fast as possible. Why are we alone? Enter the Great Filter hypothesis--*something* stops species from colonizing the galaxy. Looking at what has happened on Earth there are only three likely candidates:
1) The jump to multicellular life. It took billions of years. One data point isn't enough to determine an average but we can see it's not something that happens easily.
2) The emergence of intelligence. Same situation, again.
3) The lifespan of intelligent civilizations.
The odds of successfully crossing these three hurdles must be billions to one. Either intelligent races destroy themselves before reaching the stars or the billions to one odds are in the first two hurdles.
The most favorable interpretation for humanity is that the average time to cross those hurdles is well beyond the couple of billion years it took Earth, most planets fail to produce intelligence before their ecosystem gets fried or smacked with something substantially larger than the dinosaur killer. If this is the answer it's no surprise we squeaked in just under the wire.
And if that's not the answer humanity isn't going to be around for too much longer.
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.
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?
> 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.
I love these kinds of planetary scale thought experiments. They must be a treasure trove for sci-fi writers. Imagine being on Earth living through one of the energy transfers. Reminds me of Asimov's Nightfall.
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On the other hand, given our current blase response to climate change, I'll give you long odds against human civilization being around in a billion years, or even a million -- or, for that matter, a thousand. And unless something changes radically in the next few years, I'll give you even odds against it lasting to the end of this century.
Assuming we don't do ourselves in there will be sentients, but species are defined by the ability to interbreed and I expect genetic modification will reach the point that interbreeding with a stock human is no longer possible. At that point we will be a new species, not "human".
I hope humanity can even survive 6 thousand years.
I'd imagine after the first 10^8 years you'd probably have it sorted. Getting your organisation to last 10^2 to 10^3 years is the hard part.
Create a religion around the project, like the technicians priesthood in Asimov's Foundation or like in some proposals for long term protection of radioactive waste sites https://en.m.wikipedia.org/wiki/Long-time_nuclear_waste_warn...
"You mean to suggest a bunch of *click* _monkeys_ could steer the planet? Those creatures-in-the-dust who couldn't even survive _radiation_? You are hereby sentenced for *chirp* roach-heresy."
It's a thought exercise, not a proposal, you need not be worried about a catastrophic collision.
Bravo to the scientist for doing the calculations.
*(The solar gravity well is ~12 km/s deep and the Earth's gravity well is ~11 km/s, so dismantling the Earth and ejecting it are ~similar)
Plus, the idea is to extract the energy from Jupiter's orbit.
Sure, but going out to 1.5 au is already 1/3rd of the way to ejection.
https://orionsarm.com/eg-article/49125f5d1c049
Effectively turning 2 class A white stars, 8 times as bright as Sol into computers, power plants and fuel for them, good for the next 14 trillion years:
"Power spheres take the place of the more commonly used central star of most solar systems, but are far more efficient. The average Sol-type sun will convert only a tiny fraction of its total mass into energy in the course of a lifetime of approximately 10 billion years. The Power Sphere network of Turing is designed to provide an amount of energy equal to that of a sun but for a period of more than 14 trillion years."
Or if you need more juice, say 100000x the output of the sun, you could sustain that for about 140 millions of years. ;-)
If you are crazy enough, you might even dismantle the sun outright and store the material as (predominantly) huge hydrogen icebergs you can burn in nice efficient fusion plants for the rest of eternity. Much more efficient! :)
Still much more difficult proposition that turning a terrestrial planet into an orbital swarm.
A better option to control climate due to the sun would be to build a 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.
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?
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.
[1] http://www.antipope.org/charlie/blog-static/fiction/accelera...
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.
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.
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.
I'm not following what the mechanism is supposed to be though.
Warming increases the rate CO2 gets converted into limestone, thus lowering the temperature. 50 million years is when that pegs and the mercury starts rising.
As for it being a puzzling coincidence--it might not be a coincidence at all. Think of the Fermi Paradox--where are the aliens? These days the astronomers tell us planets are very common. A look at the emergence of life on Earth says it happened about as fast as possible. Why are we alone? Enter the Great Filter hypothesis--*something* stops species from colonizing the galaxy. Looking at what has happened on Earth there are only three likely candidates:
1) The jump to multicellular life. It took billions of years. One data point isn't enough to determine an average but we can see it's not something that happens easily.
2) The emergence of intelligence. Same situation, again.
3) The lifespan of intelligent civilizations.
The odds of successfully crossing these three hurdles must be billions to one. Either intelligent races destroy themselves before reaching the stars or the billions to one odds are in the first two hurdles.
The most favorable interpretation for humanity is that the average time to cross those hurdles is well beyond the couple of billion years it took Earth, most planets fail to produce intelligence before their ecosystem gets fried or smacked with something substantially larger than the dinosaur killer. If this is the answer it's no surprise we squeaked in just under the wire.
And if that's not the answer humanity isn't going to be around for too much longer.
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.
Perhaps an initial lift up to an unshadowed low earth orbit could boot strap a solar ion/sail to get them to L1?
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.