5 ms·

This is incredibly exciting but a few important details are missing. The first is how big does the structure need to be? I can buy a 1 Tesla magnet online righ

This is incredibly exciting but a few important details are missing. The first is how big does the structure need to be? I can buy a 1 Tesla magnet online right now but that's probably not what they're thinking of. Would we need a city-sized coil or something like that? The second is the time scale. They say that the temperature could rise by 4 Celsius and trigger a greenhouse effect, but is that an immediate effect (10 years or so) or century-scale effect? I'm hoping the scientists put out a paper because I'd love to learn more about the specifics of their proposal.

SideburnsOfDoom 10y ago
> is that an immediate effect (10 years or so) or century-scale effect? We should be so lucky. Planetary scale can be rather large and slow. For instance the oxygenation of the Earth's atmosphere took hundreds of millions of years https://en.wikipedia.org/wiki/Great_Oxygenation_Event#Time_lag_theory https://en.wikipedia.org/wiki/Great_Oxygenation_Event#Time_l...
- im3w1l 10y ago
  We have managed to warm the earth considerably in less then a century and that's without trying. I reckon if we gave it our best we could change planetary scale things even faster than that.
  - SideburnsOfDoom 10y ago
    > in less then a century The industrial revolution has been going since before 1800 https://en.wikipedia.org/wiki/Industrial_Revolution https://en.wikipedia.org/wiki/Industrial_Revolution
  - simonh 10y ago
    That was a byproduct of economically useful work though. If you can think of economically useful work that this project could generate, on an ongoing basis while it's in progress, that's greater than it's ongoing costs that would be great.
- akiselev 10y ago
  We don't know how well cyanobacteria fared against its microbial competitors, how efficient the early photosynthetic pathway was, or how large the oxygen sinks were pre-GOE saturation so we have no idea whether planetary oxygenation actually needs to take that long. Without an existing biome that captures oxygen or large bodies of water to dissolve oxides, the process can be many orders of magnitude easier (especially since Mars' atmosphere will take significantly less volume and we might be able to survive just fine with lower air density with a higher concentration of oxygen). It's extremely unlikely that we can pull it off in a human lifespan but I would bet that planetary oxygenation is possible given a few millennia
MichaelMoser123 10y ago
high altitude nuclear tests have created artificial electromagnetic radiation belts (similar to the Van Allen belt); https://en.wikipedia.org/wiki/List_of_artificial_radiation_belts https://en.wikipedia.org/wiki/List_of_artificial_radiation_b...
- mighty_atomic_c 10y ago
  Those also damage electronics far below. In fact, that is the characteristic way of using high altitude nuclear weapons to damage communications over a continental region. But far enough away it would push a little solar wind around, for a short time.
dghughes 10y ago
This is where I am confused too the speaker in the video said Earth's magnetic field is 31,000 nanoTesla. He said the best plan for a shield for Mars is a 500,000 nanoTesla field at L1 which is 320 Mars radii away from Mars. Maybe I am misunderstanding what he is saying or pronouncing, nanoTesla i.e. billionths of a Tesla?
- thatcherc 10y ago
  I imagine there is also a size component involved. The Earth's magnetic field might be 31,000 nanoTesla, but it's spread over an enormous volume. This magnetic shield would have to be much smaller than a planet, so it makes sense that it should have a much strong field.
fenollp 10y ago
Less than 700 million years apparently. https://twitter.com/humansareawesme/status/836961705745858560 https://twitter.com/humansareawesme/status/83696170574585856...
kurthr 10y ago
Yes, a magnet has both a peak magnetic field (which is what is usually quoted) and a magnetic dipole moment that is roughly proportional to diameter. The magnetic field at a distance is proportional to the moments, but falls off proportional to the inverse cube of the distance. So, yes if the magnet dipole were the size of Mars and it needed to be 5mT=500,000nT at 320 Mars diameters, then roughly (ignoring higher order effects) you would need an average 16kT around the surface poles, which isn't possible with current technology. At 1 Tesla you would want to cover an area 50 times the diameter than Mars? That's pretty fanciful. OK, either my simple calculations are bunk, or this is a truly crazy idea.
- eloff 10y ago
  It's not located on/at Mars, it's located at the Lagrange point - which means much like your hand can cover entire mountains at a distance, a smaller magnetic field could shield an entire planet when positioned between mars and the sun.
  - kurthr 10y ago
    Based on the drawing that they made the size is at least 1-2 diameters of mars (but there is no field there?). Since the diameter of Mars is ~4000mi that would >10,000km at 5mT. So with the mentioned 1-2 Tesla starting field, we end up and a cube law reducing the strength 200x at 6 times the distance, and a 1.5km moment. That would require at least 2-3km^2 of 1T magnets. Ignoring the support structure that would have a volume of ~10^10 cm^3 and weigh 100ktons, but only cost $100B on Earth at todays Samarium Cobalt pricing, if the market wasn't highly distorted. Sounds more reasonable...
    - LeanderK 10y ago
      sounds surprisingly realistic if you consider that this is a proposal to create an artificial magnetic shield for an entire planet.
    - tankenmate 10y ago
      Also, isn't there a shockwave effect?
TTPrograms 10y ago
For people asking about the amount of energy we're talking about, the energy density of a magnetic field is |B|^2 /(2mu_0). It appears that the described structure has something on the order of the cross section of Mars, and I'll assume that it's depth is in that ballpark as well. For a fictitious uniform field that would require on the order of 1.6e19 J, which is roughly 1.2 times the total electrical energy output of the US in 2001: http://www.wolframalpha.com/input/?i=4%2F3+pi+*+(radius+of+mars)%5E3+*+(500,000+nT)%5E2+%2F+(2*mu_0) http://www.wolframalpha.com/input/?i=4%2F3+pi+*+(radius+of+m... http://www.wolframalpha.com/input/?i=1.617%C3%9710%5E19+joules&lk=1&rawformassumption=%22ClashPrefs%22+-%3E+%22ClashPrefs%22 http://www.wolframalpha.com/input/?i=1.617%C3%9710%5E19+joul... Assuming you had no losses, so say ideal superconducting coils, that's how much energy you have to dump into magnetic field. You can do this as slow as you like, so with 1/10 the US electrical energy production it would take 10 years to build up that magnetic field. Hypothetically, if you had thin-film plastic PV cells (like cellophane thin to be reasonable to build and get into space) with 100% efficiency covering the footprint of this system (Mars) you could generate enough power to charge up this field in 471 seconds: http://www.wolframalpha.com/input/?i=1e19+J+%2F+((solar+power+output*pi*(radius+of+mars%5E2))%2F(4*pi*radius+of+mars+orbit%5E2) http://www.wolframalpha.com/input/?i=1e19+J+%2F+((solar+powe...) Of course the big story here is that efficient thin film solar in space could generate obscene amounts of power. I'm not sure on the depth of the field volume required, so that might make it easier, too.
- credit_guy 10y ago
  I wonder if a very large array of solar panels would not also act like a solar sail that would would catch enough solar wind to escape the pull of the L1 Lagrange point.
  - btown 10y ago
    Absolutely this would have an effect: https://en.wikipedia.org/wiki/Solar_sail#Trajectory_corrections https://en.wikipedia.org/wiki/Solar_sail#Trajectory_correcti... Presumably, though, some of the power generated could be used to accelerate propellant to compensate.
  - 10y ago
Natsu 10y ago
How do they keep the magnet in place, though? Won't the solar wind pushing against it push it out of there? I mean, I know that's a stable Lagrange point, but you have to wonder if it could end up moving and or spinning around after enough solar flares hit it and what that would do.
Geee 10y ago
I think the general idea to terraform in a reasonable time is to nuke the poles to release CO2.
- sitkack 10y ago
  Even if one did this, any atmosphere on Mars would be temporary as the solar wind would eventually strip it away. The magnetic field is required for long term viability.
  - cgriswald 10y ago
    You're not wrong, but that's kind of a non-issue. It takes on the order of hundreds of millions of years to lose that much atmosphere.
    - jaimex2 10y ago
      Porque no los dos?
    - sitkack 10y ago
      So you are saying we could crash some comets, boil the CO2/ice caps and solve the magnetosphere issue later?
      - LeanderK 10y ago
        well, this is a serious proposal to solve the magnetosphere-problem! We could build this AND nuke the plant. Or we could at least use this as an indicator that the problem is solvable over a few centuries and start nuking. Better sooner than later!

SideburnsOfDoom 10y ago

> is that an immediate effect (10 years or so) or century-scale effect? We should be so lucky. Planetary scale can be rather large and slow. For instance the oxygenation of the Earth's atmosphere took hundreds of millions of years https://en.wikipedia.org/wiki/Great_Oxygenation_Event#Time_lag_theory https://en.wikipedia.org/wiki/Great_Oxygenation_Event#Time_l...

im3w1l 10y ago
We have managed to warm the earth considerably in less then a century and that's without trying. I reckon if we gave it our best we could change planetary scale things even faster than that.
- SideburnsOfDoom 10y ago
  > in less then a century The industrial revolution has been going since before 1800 https://en.wikipedia.org/wiki/Industrial_Revolution https://en.wikipedia.org/wiki/Industrial_Revolution
- simonh 10y ago
  That was a byproduct of economically useful work though. If you can think of economically useful work that this project could generate, on an ongoing basis while it's in progress, that's greater than it's ongoing costs that would be great.
akiselev 10y ago
We don't know how well cyanobacteria fared against its microbial competitors, how efficient the early photosynthetic pathway was, or how large the oxygen sinks were pre-GOE saturation so we have no idea whether planetary oxygenation actually needs to take that long. Without an existing biome that captures oxygen or large bodies of water to dissolve oxides, the process can be many orders of magnitude easier (especially since Mars' atmosphere will take significantly less volume and we might be able to survive just fine with lower air density with a higher concentration of oxygen). It's extremely unlikely that we can pull it off in a human lifespan but I would bet that planetary oxygenation is possible given a few millennia

MichaelMoser123 10y ago

high altitude nuclear tests have created artificial electromagnetic radiation belts (similar to the Van Allen belt); https://en.wikipedia.org/wiki/List_of_artificial_radiation_belts https://en.wikipedia.org/wiki/List_of_artificial_radiation_b...

mighty_atomic_c 10y ago
Those also damage electronics far below. In fact, that is the characteristic way of using high altitude nuclear weapons to damage communications over a continental region. But far enough away it would push a little solar wind around, for a short time.

dghughes 10y ago

This is where I am confused too the speaker in the video said Earth's magnetic field is 31,000 nanoTesla. He said the best plan for a shield for Mars is a 500,000 nanoTesla field at L1 which is 320 Mars radii away from Mars. Maybe I am misunderstanding what he is saying or pronouncing, nanoTesla i.e. billionths of a Tesla?

thatcherc 10y ago
I imagine there is also a size component involved. The Earth's magnetic field might be 31,000 nanoTesla, but it's spread over an enormous volume. This magnetic shield would have to be much smaller than a planet, so it makes sense that it should have a much strong field.

fenollp 10y ago

Less than 700 million years apparently. https://twitter.com/humansareawesme/status/836961705745858560 https://twitter.com/humansareawesme/status/83696170574585856...

kurthr 10y ago

Yes, a magnet has both a peak magnetic field (which is what is usually quoted) and a magnetic dipole moment that is roughly proportional to diameter. The magnetic field at a distance is proportional to the moments, but falls off proportional to the inverse cube of the distance. So, yes if the magnet dipole were the size of Mars and it needed to be 5mT=500,000nT at 320 Mars diameters, then roughly (ignoring higher order effects) you would need an average 16kT around the surface poles, which isn't possible with current technology. At 1 Tesla you would want to cover an area 50 times the diameter than Mars? That's pretty fanciful. OK, either my simple calculations are bunk, or this is a truly crazy idea.

eloff 10y ago
It's not located on/at Mars, it's located at the Lagrange point - which means much like your hand can cover entire mountains at a distance, a smaller magnetic field could shield an entire planet when positioned between mars and the sun.
- kurthr 10y ago
  Based on the drawing that they made the size is at least 1-2 diameters of mars (but there is no field there?). Since the diameter of Mars is ~4000mi that would >10,000km at 5mT. So with the mentioned 1-2 Tesla starting field, we end up and a cube law reducing the strength 200x at 6 times the distance, and a 1.5km moment. That would require at least 2-3km^2 of 1T magnets. Ignoring the support structure that would have a volume of ~10^10 cm^3 and weigh 100ktons, but only cost $100B on Earth at todays Samarium Cobalt pricing, if the market wasn't highly distorted. Sounds more reasonable...
  - LeanderK 10y ago
    sounds surprisingly realistic if you consider that this is a proposal to create an artificial magnetic shield for an entire planet.
  - tankenmate 10y ago
    Also, isn't there a shockwave effect?

TTPrograms 10y ago

For people asking about the amount of energy we're talking about, the energy density of a magnetic field is |B|^2 /(2mu_0). It appears that the described structure has something on the order of the cross section of Mars, and I'll assume that it's depth is in that ballpark as well. For a fictitious uniform field that would require on the order of 1.6e19 J, which is roughly 1.2 times the total electrical energy output of the US in 2001: http://www.wolframalpha.com/input/?i=4%2F3+pi+*+(radius+of+mars)%5E3+*+(500,000+nT)%5E2+%2F+(2*mu_0) http://www.wolframalpha.com/input/?i=4%2F3+pi+*+(radius+of+m... http://www.wolframalpha.com/input/?i=1.617%C3%9710%5E19+joules&lk=1&rawformassumption=%22ClashPrefs%22+-%3E+%22ClashPrefs%22 http://www.wolframalpha.com/input/?i=1.617%C3%9710%5E19+joul... Assuming you had no losses, so say ideal superconducting coils, that's how much energy you have to dump into magnetic field. You can do this as slow as you like, so with 1/10 the US electrical energy production it would take 10 years to build up that magnetic field. Hypothetically, if you had thin-film plastic PV cells (like cellophane thin to be reasonable to build and get into space) with 100% efficiency covering the footprint of this system (Mars) you could generate enough power to charge up this field in 471 seconds: http://www.wolframalpha.com/input/?i=1e19+J+%2F+((solar+power+output*pi*(radius+of+mars%5E2))%2F(4*pi*radius+of+mars+orbit%5E2) http://www.wolframalpha.com/input/?i=1e19+J+%2F+((solar+powe...) Of course the big story here is that efficient thin film solar in space could generate obscene amounts of power. I'm not sure on the depth of the field volume required, so that might make it easier, too.

credit_guy 10y ago
I wonder if a very large array of solar panels would not also act like a solar sail that would would catch enough solar wind to escape the pull of the L1 Lagrange point.
- btown 10y ago
  Absolutely this would have an effect: https://en.wikipedia.org/wiki/Solar_sail#Trajectory_corrections https://en.wikipedia.org/wiki/Solar_sail#Trajectory_correcti... Presumably, though, some of the power generated could be used to accelerate propellant to compensate.
- 10y ago

Natsu 10y ago

How do they keep the magnet in place, though? Won't the solar wind pushing against it push it out of there? I mean, I know that's a stable Lagrange point, but you have to wonder if it could end up moving and or spinning around after enough solar flares hit it and what that would do.

Geee 10y ago

I think the general idea to terraform in a reasonable time is to nuke the poles to release CO2.

sitkack 10y ago
Even if one did this, any atmosphere on Mars would be temporary as the solar wind would eventually strip it away. The magnetic field is required for long term viability.
- cgriswald 10y ago
  You're not wrong, but that's kind of a non-issue. It takes on the order of hundreds of millions of years to lose that much atmosphere.
  - jaimex2 10y ago
    Porque no los dos?
  - sitkack 10y ago
    So you are saying we could crash some comets, boil the CO2/ice caps and solve the magnetosphere issue later?
    - LeanderK 10y ago
      well, this is a serious proposal to solve the magnetosphere-problem! We could build this AND nuke the plant. Or we could at least use this as an indicator that the problem is solvable over a few centuries and start nuking. Better sooner than later!