Impact on space travel
Solar cells, integrated circuits, and sensors can be damaged by radiation. Geomagnetic storms occasionally damage electronic components on spacecraft. Miniaturization and digitization of electronics and logic circuits have made satellites more vulnerable to radiation, as incoming ions may be as large as the circuit's charge. Electronics on satellites must be hardened against radiation to operate reliably. The Hubble Space Telescope, among other satellites, often has its sensors turned off when passing through regions of intense radiation.
Missions beyond low earth orbit leave the protection of the geomagnetic field, and transit the Van Allen belts. Thus they may need to be shielded against exposure to cosmic rays, Van Allen radiation, or solar flares. The region between two to three earth radii lies between the two radiation belts and is sometimes referred to as the "safe zone".
A satellite shielded by 3 mm of aluminium in an elliptic orbit (200 by 20,000 miles) passing through the radiation belts will receive about 2,500 rem (25 Sv) per year. Almost all radiation will be received while passing the inner belt. 
and some cool pics!
Simulated Van Allen Belts generated by a plasma thruster in tank #5 Electric Propulsion Laboratory