Van Allen Probe A
NASA

NASA's Van Allen Probe A re-entered Earth's atmosphere on 11 March, nearly eight years earlier than projected. The U.S. Space Force confirmed the 600-kilogram (1,323-pound) spacecraft burned up over the eastern Pacific Ocean at 6:37 a.m. EDT, at approximately 2 degrees south latitude and 255.3 degrees east longitude.

NASA said the probability of any surviving debris causing harm to a person was approximately 1 in 4,200, or around 0.02%. No injuries or debris strikes were reported.

'Almost all the object is expected to burn up during reentry,' NASA said in a statement. 'There is no targeted area for the landing if any components survive.'

About 70% of Earth's surface is covered by ocean, which NASA noted made it far more likely that any surviving fragments would land in open water rather than near populated areas. By comparison, when China's Tiangong-1 space station made an uncontrolled re-entry in 2018, the probability of debris striking a person was estimated at less than one in a trillion, according to CNN. No one was harmed in that incident.

Why the Van Allen Probe Returned Eight Years Early

Van Allen Probe A launched on 30 August 2012 alongside its twin, Van Allen Probe B, from Cape Canaveral. Both spacecraft were built for a two-year mission to study the Van Allen radiation belts - zones of high-energy charged particles held in place by Earth's magnetic field, stretching from around 640 kilometres to 58,000 kilometres above the surface. The belts act as a shield against solar radiation, cosmic storms, and the constant stream of charged particles from the Sun.

The probes operated for nearly seven years. NASA ended the mission in 2019 after both spacecraft ran out of fuel and could no longer orient themselves towards the Sun. The mission was managed and operated by the Johns Hopkins University Applied Physics Laboratory.

When the mission concluded, NASA's analysis projected Probe A would re-enter the atmosphere around 2034. Those calculations preceded the current solar cycle, which proved far more active than anticipated. Scientists confirmed in 2024 that the Sun had reached solar maximum - the peak of its roughly 11-year activity cycle. The resulting space weather events heated and expanded the upper atmosphere, increasing drag on the dormant spacecraft and accelerating its orbital decay by nearly eight years, according to NASA.

Van Allen Probe B remains in orbit. NASA does not expect it to re-enter before 2030.

What the Van Allen Probe Spacecraft Discovered

The twin probes were the first spacecraft designed to operate for extended periods within the radiation belts, a region most missions pass through as quickly as possible to limit radiation exposure. According to NASA, the mission produced the first data confirming the existence of a transient third radiation belt - a temporary outer ring that can form during periods of intense solar activity. The probes also gathered measurements showing how electrons within the belts can be accelerated to near the speed of light by plasma waves from solar storms.

Archived data from the mission continues to feed models used for space weather forecasting. NASA said the research helps predict how solar activity affects satellites, astronauts, and systems on Earth, including communications, navigation, and power grids.

Uncontrolled re-entries of defunct satellites and spent rocket stages occur on a near-daily basis, according to the European Space Agency, with the vast majority of objects disintegrating before reaching the ground. At 600 kilograms, Probe A was considerably heavier than the average piece of returning orbital hardware.

Space debris expert Marlon Sorge of The Aerospace Corporation told CNN that had the mission launched today, NASA might have designed the spacecraft to ensure no components survived re-entry. That approach has become increasingly standard among modern satellite operators.

Dr Darren McKnight, a senior technical fellow at space-tracking company LeoLabs, told CNN that roughly one dead rocket body or defunct payload re-enters the atmosphere each week. In 2024, a piece of debris jettisoned from the International Space Station survived re-entry and struck a home in Florida.

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