A pair of small robotic spacecraft called the Van Allen probes have been exploring the radiation belts around Earth to learn about how particles move through the belts and how the belts are affected by geomagnetic storms. Now the probes are moving into the final phase of their exploration, coming closer to Earth to gather more data before burning up safely in the atmosphere without creating space debris.
The probes were launched in August 2012 to explore the band of hazardous charged particles that make up the Earth’s radiation belts. These doughnut-shaped belts consist of energized protons and electrons which are trapped by Earth’s magnetic fields, and which move at a high speed. The belts are considered hazardous because the particles create radiation which can cause problems with the electronics on board satellites, and they could even affect the health of astronauts who pass through them on their way into space. Though they are dangerous, the belts can also be beautiful — they are what causes auroras in the night sky like the famous Northern Lights.
The radiation belts are highly dynamic, and their size, shape, and intensity can all change depending on factors like solar activity. Scientists wanted to learn more about how the belts change in response to environmental factors, so the Van Allen probes were launched as a two-year mission to collect data on the processes happening within the belt. The mission was designated as a two-year duration because it was believed that was the maximum that a craft could be operational in the harsh radiation environment. But remarkably, the probes have proved hardier than anyone could have hoped and have been operational for seven years now.
“The Van Allen Probes mission has done a tremendous job in characterizing the radiation belts and providing us with the comprehensive information needed to deduce what is going on in them,” David Sibeck, mission scientist for the Van Allen Probes at NASA’s Goddard Space Flight Center, said in a statement. “The very survival of these spacecraft and all their instruments, virtually unscathed, after all these years is an accomplishment and a lesson learned on how to design spacecraft.”
Both of the twin probes will gradually be moved to a new orbit, sitting around 190 miles (306 kilometers) above the Earth’s surface to collect more data until they run out of fuel. After about fifteen years, the probes will re-enter the Earth’s atmosphere, gathering some final data on oxygen in the upper atmosphere before safely disintegrating.
