The Van Allen Probes, the second mission of NASA's Living With a Star program, are providing unprecedented insight into the physical dynamics of the radiation belts and are providing scientists the data they need to make predictions of changes in this critical region of space.

Since their launch on Aug. 30 2012, the two Van Allen Probes have orbited the Earth, sampling the harsh radiation belt environment where major space weather activity occurs and many spacecraft operate.

The two spacecraft are measuring the particles, magnetic and electric fields, and waves that fill geospace. Only with two spacecraft taking identical measurements, and following the same path, can scientists begin to understand how the belts change in both space and time.