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by mratzloff 3101 days ago
That wouldn't do much good unless we can re-establish the magnetosphere.
4 comments

I don't think that's necessary. The loss of atmosphere by Mars may have been significant on the timescale of its five-billion-years history, but not on the timescale of a human settlement project.

The mass of the Martian atmosphere is about 25 teratonnes [1]. According to the measurements by MAVEN, the rate of mass loss by Martian atmosphere due to solar wind is 100 g/s [2]. At this rate it would take

    25e12 * 1000 * 1000 * 0.01 / 100 / 3600 / 24 / 365.25 = 79 million years
for Mars to loose 1% of the mass of its atmosphere. Even if the rate of mass loss were 10 times higher than measured by MAVEN (it's known to increase during solar storms and in perihelium), it'd still take nearly 8 million years.

Looks like if we can increase density and pressure of Martian atmosphere as GP suggested, we don't really need to worry about the lack of magnetospheric protection.

[1] https://en.wikipedia.org/wiki/Atmosphere_of_Mars [2] https://www.nasa.gov/press-release/nasa-mission-reveals-spee...

I think it is still an open (and hotly debated) question on if planets need magnetospheres to retain an atmosphere.
* also, retain an atmosphere "over long enough timescales"

From the MAVEN research papers I've read, we're talking ~5,000 metric tons / yr of atmosphere being stripped.

Which is a lot, but not an insurmountable lot.

A magnetosphere is required to shield from charges particles and other harmful radiation.
Mars has isolated pockets of "mini magnetospheres" that are suitable enough to block charged particles.

http://www.space.dtu.dk/english/Research/Universe_and_Solar_...

I think he was assuming the subject was terraforming.

Without a magnetosphere, the atmosphere will keep being blasted off into space continuously, and it'll be impossible to terraform.

Continuously, but slowly, over very long time scales. Maintaining an atmosphere suitable for us is probably far easier than constructing it in the first place.
Ah yeah, forgot about that. And restarting the core dynamo seems pretty infeasible regardless or our technological capabilities.