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Engineers at the Applied Physics Lab in Maryland on July 19 turned off one of the two Van Allen probes, with the second probe expected to receive a similar command later this year.
As expected, following final de-orbit maneuvers in February of this year, the spacecraft has used its remaining propellant to keep its solar panels pointed at the Sun and is now out of fuel. Since it depends on the Sun to provide power to the instruments, and can no longer orient itself to acquire power, the spacecraft has been turned off. The spacecraft is in a stable, circular orbit around Earth and, in about 15 years, will re-enter the atmosphere and burn up safely. The de-orbit maneuvers in February were designed to ensure this would happen and prevent the spacecraft from becoming “space junk” in orbit.
The other Van Allen Probes spacecraft, spacecraft A, is expected to operate normally until early September.
Both spacecraft functioned five years longer than expected, and during that time discovered that there are three Van Allen belts, not two as previously thought.