Please go read Gunnell, et al, 2018, "Why an Intrinsic Magnetic Field Does Not Protect a Planet Against Atmospheric Escape", A&A 614.
Please also go read Sakai, et al, 2018, "Effects of a Weak Intrinsic Magnetic Field on Atmospheric Escape From Mars", GRL Vol 45 Issue 18.
Your entire post is based on the flawed premise that magnetospheres shield atmospheres, while also ignoring the polar wind generated by such magnetospheres, leading to even greater atmospheric losses. To quote Gunnell: "contrary to what has been believed and reported in the press, the presence of a strong planetary magnetic field does not necessarily protect a planet from losing its atmosphere."
Please go read Gunnell, et al, 2018, "Why an Intrinsic Magnetic Field Does Not Protect a Planet Against Atmospheric Escape", A&A 614.
Please also go read Sakai, et al, 2018, "Effects of a Weak Intrinsic Magnetic Field on Atmospheric Escape From Mars", GRL Vol 45 Issue 18.
Your entire post is based on the flawed premise that magnetospheres shield atmospheres, while also ignoring the polar wind generated by such magnetospheres, leading to even greater atmospheric losses. To quote Gunnell: "contrary to what has been believed and reported in the press, the presence of a strong planetary magnetic field does not necessarily protect a planet from losing its atmosphere."