Van Allen Probes enter last phase of radiation belt exploration

NASA has announced that the twin Van Allen Probes that have been orbiting the Earth for over six years are entering their final phase of exploration. The probes have been exploring the Earth's radiation belts since they launched in 2012. During their mission, the Van Allen Probes have confirmed scientific theories and revealed new structures and processes to scientists.

The final phase of the exploration will start on February 12, 2019, when one of the twin Van Allen Probes kicks off a series of orbit descent maneuvers to bring the lowest point of its orbit to Earth at just under 190 miles. That lowest point of the orbit is called the perigee.

The probe's perigee will decrease from about 375 miles to about 190 miles to position the spacecraft for an eventual re-entry to the Earth's atmosphere about 15 years from now. The goal of the mission now is to use aerodynamic drag to bring the satellites in the atmosphere where they will eventually burn up instead of becoming space debris.

In March, the second Van Allen Probe will begin its orbit decrease. The probes orbit in the radiation belts of the Earth in an area filled with fast-moving particles that can interfere with satellite electronics and pose threats to astronauts who pass through them. The size and shape of the radiation belts change in response to solar activity.

The Van Allen Probes have been sending back useful data to researchers for much longer than the intended 2-year mission. Predictions were that no spacecraft could operate in the hazardous radiation belts for longer than two years, but the probes have proven that wrong by operating since 2012 with no incidents. The burns to change the orbits will require a series of five two-hour burns for each probe.