The Van Allen Belts, also known as the Van Allen radiation belts, are a topic of interest and study. There is disagreement about the implications of the Van Allen Belts, with some suggesting they pose a significant challenge to human spaceflight, while others argue this is not the case. A NASA spacecraft, the Van Allen Probe A, has burned up over the Pacific after spending time in space studying the belts, although reports differ on the circumstances of its return to Earth.