"The underlying cause wipes out your extra planet solutions."
Not really as Mars (currently) has a solid core and very little electromagnetic field. Additionally, if we built the Dyson Sphere around our Sun the solar system would be in an eternal "Grand Solar Minimum" and Earth's Magnetic Pole swaps should end. for good!
According to the evidence, the solar system goes through a cloud of dust every few thousand years. The dust accumulates on the surface until it is ejected. The resultant CME(s) can be solar particles that have 1000 times the energy of X-rays, microtektites (like shotgun pellets), and larger masses. The projectiles that hit during the Younger Dryas were sufficient to put Earth back into a glaciation for 1000 years.
This event is supposed to happen anytime between now and about 25 years from now. I doubt if anything significant could be built on Mars in the remaining time.
You realize that the Sun is a million times larger than Earth. There isn't enough matter in the Solar system to create a Dyson Sphere.
Here are excerpts detailing the evidence of micro-tektites.
PS. It is better not to broadcast this information. If it is wrong, there is no problem aside from a number of people looking foolish. If it is correct, you might want to investigate how people survived the last time.
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