> and so the researchers cannot definitively say that Mars ever had a magnetic field We know that Mars had a dynamo-effect in the past from various measurement

> and so the researchers cannot definitively say that Mars ever had a magnetic field We know that Mars had a dynamo-effect in the past from various measurements of the magnetization in its crust, indicating that it had a magnetic field. https://en.wikipedia.org/wiki/Magnetic_field_of_Mars https://en.wikipedia.org/wiki/Magnetic_field_of_Mars