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A lot of people get fooled into thinking that because Mars lacks an atmosphere due to a lack of a magnetic field, a magnetic field is required to have an atmosp

A lot of people get fooled into thinking that because Mars lacks an atmosphere due to a lack of a magnetic field, a magnetic field is required to have an atmosphere. The atmosphere was stripped away from Mars over hundreds of millions of years. If you could somehow restore the atmosphere today, it would remain just fine over any reasonable human timescales. Giving Mars at atmosphere is of course very difficult.

goatlover 7y ago
The magnetic field is needed to protect life on Mars from radiation. It's one of the bigger problems in terraforming the planet.
- russdill 7y ago
  The atmosphere is what blocks radiation, not the magnetosphere.
  - goatlover 7y ago
    https://science.nasa.gov/heliophysics/focus-areas/magnetosphere-ionosphere https://science.nasa.gov/heliophysics/focus-areas/magnetosph...
    - russdill 7y ago
      That's a pretty simplistic explanation. If you look at the details, the magnetosphere is protecting the atmosphere. Take each kind of radiation in turn. X-Rays: The magnetosphere has no effect UV: The magnetosphere has no effect Cosmic rays: While both the Earth's magnetic field and the sun's magnetic deflect some cosmic rays, the Earth's atmosphere is mostly opaque to cosmic rays. Solar wind/coronal mass ejections: The Earth's magnetic field does block these, but if it wasn't present, the atmosphere would block them (but of course be slowly stripped away in the process) The fact that the magnetosphere does deflect some particles but isn't what makes life on Earth possible (other than protecting the atmosphere) is made most clear by the ISS being well within the magnetosphere but still receiving hundreds of times the amount on Earth.
      - srajabi 7y ago
        But if we had the artificial magnetosphere and then populated the atmosphere we would get similar effects to Earth's protection?
        russdill 7y ago
        You're never going to get the same atmosphere on Mars vs Earth. Not only are you going to need to make a lot of tradeoffs with respect to gas content (eg, that much nitrogen is going to be very difficult to find/relocate) but the same amount of atmospheric pressure is going to take a larger mass of atmosphere since there is less gravity. So it really is a hard question to answer since to answer it you'd need to know what kind of atmosphere Mars would have.
        anticensor 7y ago
        You could replace some of nitrogen by argon to defeat pressure issues.

goatlover 7y ago

The magnetic field is needed to protect life on Mars from radiation. It's one of the bigger problems in terraforming the planet.

russdill 7y ago
The atmosphere is what blocks radiation, not the magnetosphere.
- goatlover 7y ago
  https://science.nasa.gov/heliophysics/focus-areas/magnetosphere-ionosphere https://science.nasa.gov/heliophysics/focus-areas/magnetosph...
  - russdill 7y ago
    That's a pretty simplistic explanation. If you look at the details, the magnetosphere is protecting the atmosphere. Take each kind of radiation in turn. X-Rays: The magnetosphere has no effect UV: The magnetosphere has no effect Cosmic rays: While both the Earth's magnetic field and the sun's magnetic deflect some cosmic rays, the Earth's atmosphere is mostly opaque to cosmic rays. Solar wind/coronal mass ejections: The Earth's magnetic field does block these, but if it wasn't present, the atmosphere would block them (but of course be slowly stripped away in the process) The fact that the magnetosphere does deflect some particles but isn't what makes life on Earth possible (other than protecting the atmosphere) is made most clear by the ISS being well within the magnetosphere but still receiving hundreds of times the amount on Earth.
    - srajabi 7y ago
      But if we had the artificial magnetosphere and then populated the atmosphere we would get similar effects to Earth's protection?
      - russdill 7y ago
        You're never going to get the same atmosphere on Mars vs Earth. Not only are you going to need to make a lot of tradeoffs with respect to gas content (eg, that much nitrogen is going to be very difficult to find/relocate) but the same amount of atmospheric pressure is going to take a larger mass of atmosphere since there is less gravity. So it really is a hard question to answer since to answer it you'd need to know what kind of atmosphere Mars would have.
        anticensor 7y ago
        You could replace some of nitrogen by argon to defeat pressure issues.