The malfunction of the "Midori-2" satellite in October 2003 was the latest in a series of radiation-induced satellite failures in a region in the southern hemisphere known as South Atlantic Anomaly due to the reduced magnetic field intensity.
While the earth magnetic field protects us from the continuous flow of charged particles, the solar wind, before it reaches the atmosphere, its dominant axial dipole component is currently decreasing at a rate presumably ten times faster than the one at which it would naturally decay. It has decreased by nearly 8% over the last 150 years, however, in some regions, as the South Atlantic Anomaly, the field has decreased by up to 10% during the last 20 years.
Understanding how this weakening shield is going to evolve in the future will have to be addressed by a better mapping of the time-variable geomagnetic field. This will provide new insights into field generation and diffusion, and mass and wave motions in the fluid core.
The increase in resolution of the lithospheric magnetism will tell us about both the history of the global field and geological activity and will serve as a bridge between our knowledge of the lower crust from previous satellite missions and our knowledge of the upper crust from aeromagnetic surveys. First global 3-D images of the electrical conductivity in the mantle could help to understand mantle properties and dynamics.
Finally, the magnetic field is of primary importance for the external environment of the Earth, providing information about the coupled Sun-Earth system.