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[deleted] t1_je5zek7 wrote

Reply to comment by cjameshuff in Can we make Mars's magnetosphere stronger? by HuygensCrater

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cjameshuff t1_je6137m wrote

There isn't a "point" to a magnetosphere, we just happen to have one. Its importance as a radiation shield is wildly exaggerated, and Earth regularly goes through periods with no strong, organized global field. The existing atmosphere of Mars provides more surface protection than Earth's magnetosphere provides in LEO, and Earth's atmosphere provides most of its protection from cosmic rays. A terraformed Mars would have an atmosphere with nearly 3 times the column mass due to its lower gravity, and even without an magnetosphere would have far better protection than Earth.

As for orbit, only LEO is protected. Satellites and probes are better off outside the magnetosphere than they are in medium Earth orbit where the belts are, and missions with humans have to plan trajectories that take them around the belts. And geomagnetic storms only pose a problem on Earth because we have a large magnetic field to get buffeted around by changes in the solar wind that we otherwise wouldn't notice.

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[deleted] t1_je6gvkx wrote

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cjameshuff t1_je6vbll wrote

Then you might find this interesting: https://www.jpl.nasa.gov/images/pia03480-estimated-radiation-dosage-on-mars

The main impact of a magnetosphere is that it protects atmospheric water from having its hydrogen split off by the solar wind, and then escaping, which hydrogen is far more prone to doing due to its lower molecular mass. Hence why Venus is bone dry but has nearly a hundred times as much atmosphere as Earth despite getting twice as much solar radiation. This is far too slow to be of significance to human activities, though. Terraforming will involve undoing billions of years of losses in just centuries, if you can terraform a planet then maintaining its environment is trivial.

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