Within days of being launched, two NASA Van Allen probes made a major discovery: the Earth has a previously unknown third Van Allen radiation belt! Normally, a new probe goes through a slow power up and testing procedure that may take months but an unexpected Coronal mass ejection from the Sun caused the Van Allen belts to swell and caused the scientists to risk a quick power up to take advantage of the rare opportunity. The findings were so unexpected, they took the researchers by surprise and even made them doubt the instrument readings:
"By the fifth day REPT was on, we could plot out our observations and watch the formation of a third radiation belt," says Shri Kanekal, the deputy mission scientist for the Van Allen Probes at NASA's Goddard Space Flight Center in Greenbelt, Md. and a coauthor of a paper on these results. "We started wondering if there was something wrong with our instruments. We checked everything, but there was nothing wrong with them. The third belt persisted beautifully, day after day, week after week, for four weeks."
The Van Allen probes are eight-sided robotic spacecraft about 6 feet across, 3 feet high and weighing in at 1,475 lbs each. The probes contain a wide range of sensors including a Relativistic Proton Spectrometer, an electric field and wave sensor with six antenna that are each 130 feet long, and a 3 axis magnetic field sensor that can determine the speed and energy level of particles in the Van Allen belts. Because the probes must operate within the Van Allen belts, they're designed to withstand radiation levels and constant particle bombardment that would destroy conventional satellites. In fact, part of what researchers hope to learn from the data collected by these probes is how to build better radiation-hardened spacecraft. Read on to see a video representation of the actual data returned by the probes as well as a video explaining the mission.