This looks to be from NPR. Anyone see any propaganda content?
Just one more thing to worry about.
He misses one other thing. What protects the Earth’s atmosphere is the Earth’s magnetic field, thanks to the spinning molten iron core. While Mars has a day similar to Earth’s, its core has solidified, thus its field is a mere remnant of what it likely was.
The resulting magnetosphere deflects much of the solar wind, which would otherwise ablate the atmosphere (as what likely happened with Mars).
Venus probably has a molten iron core, but does not rotate like Earth’s due to some tidal lock.
Mars they think billions of years ago had a much thicker atmosphere. They say it was destroyed by cosmic radiation when the planet lost its magnetic field and could no longer repel the charged particles. It lost its magnetic field when the core cooled down to the point where it could no longer generate a field.
They know this because magnetic minerals in the ancient bedrock are aligned in one direction while similar minerals in much younger lava rock are not. Both sets of rock were once molten and so minerals were free to align to a magnetic field, if one were present.