The Van Allen Probe A, a 1,300-pound spacecraft, is projected to re-enter Earth’s atmosphere on Tuesday at approximately 19:45 EST (00:45 GMT). Initially launched in 2012 with a mission duration of two years, the probe has astonishingly operated for nearly seven years, gathering invaluable data about Earth’s radiation belts.
The twin Van Allen Probes were designed to study the two persistent radiation belts that loop around Earth. Yet these belts are critical for shielding our planet from dangerous cosmic radiation and solar activity. In its active years from 2012 to 2019, the probes raced through clouds of supercharged particles. These are charged particles that are trapped by Earth’s magnetic field. This impressive mission led to many groundbreaking discoveries, such as the first ever identification of a transient third radiation belt.
Even as the Van Allen Probe A gets closer to re-entry, there is still about a 24-hour margin of uncertainty concerning exactly when that will happen. As soon as the spacecraft hits the atmosphere, experts expect it to mostly disintegrate. They think some of the components could withstand the intense heat and pressure. The chances that any piece of debris will cause harm are very low—one in 4,200.
The Van Allen Probes continued to function for additional years–beyond their intended mission duration–while providing key discoveries. They provided insight into how particles are accreted and lost in the radiation belts. They equipped scientists with a deeper understanding of these belts’ dynamics, which play an essential role in protecting Earth’s environment from solar storms and solar wind.
Our Van Allen Probe A is getting ready for a return to the atmosphere in the not-too-distant future. In the meantime, Van Allen Probe B will continue its mission at least through 2030. Both probes have a long life, underscoring their importance to continuing space science. They are key ingredients to expanding our knowledge of Earth’s complex magnetic environment.