A NASA spacecraft is set to make an uncontrolled plunge back to Earth. Here are the risks

A NASA Spacecraft Aims for an Uncontrolled Descent to Earth

The Van Allen Probe A, a retired NASA satellite, is set to re-enter Earth’s atmosphere soon, with the event possibly occurring as early as Tuesday evening—far earlier than initially forecast. While the majority of the craft will likely disintegrate during reentry, some parts may survive, NASA has indicated. The probe, weighing 1,323 pounds (600 kilograms), is expected to impact the atmosphere around 7:45 p.m. ET Tuesday, though the timing remains uncertain by up to 24 hours, per NASA and the US Space Force.

Risk Assessment and Historical Context

The probability of debris from the probe causing injury to a person is approximately 1 in 4,200, as outlined in a NASA news release. This likelihood is deemed low, yet more significant than earlier space debris events. “We’ve had instances where reentries carried a 1 in 1,000 chance, and nothing happened,” remarked Dr. Darren McKnight, a senior technical fellow at LeoLabs. “If we have a few with odds of 1 in 4,000 or 5,000, it’s not a catastrophic event for humanity,” he added.

“We’ve had instances where reentries carried a 1 in 1,000 chance, and nothing happened.” – Dr. Darren McKnight, LeoLabs

In contrast, the 2018 reentry of China’s space station was far more alarming, with estimates suggesting a less than one-in-a-trillion chance of debris impacting someone. Despite that, no casualties were reported. The current risk, while notable, is considered manageable, according to NASA officials.

Scientific Mission and Early Return

Van Allen Probe A was launched in 2012 alongside its twin, Van Allen Probe B, to investigate Earth’s radiation belts—two zones of energetic particles held in place by the planet’s magnetic field. These belts, located between 400 and 93,300 miles (640 to 58,000 kilometers) above Earth, act as a shield against cosmic radiation and solar storms. NASA emphasized the importance of studying them to understand their role in protecting Earth.

Originally, NASA planned for the probes to re-enter the atmosphere in 2034. However, the recent solar maximum in 2024, which brought heightened solar activity, accelerated the process. “These conditions increased atmospheric drag on the spacecraft beyond initial estimates, leading to an earlier re-entry,” NASA explained in a Tuesday statement. The Van Allen Probe B is also projected to follow suit, with its re-entry expected before 2030.

Disposal Strategies and Orbital Risks

NASA’s protocols mandate that spacecraft be either deorbited or safely placed in a graveyard orbit within 25 years of mission completion. While graveyard orbits allow satellites to remain in space without immediate risk, they still pose collision hazards. Dr. McKnight noted that retaining the probes in such orbits would have consumed additional fuel, limiting their scientific potential.

Initially, mission planners designed maneuvers to ensure the probes would burn up upon reentry, avoiding long-term orbital hazards. This approach prevents the spacecraft from lingering in Earth’s orbit, where they might threaten active satellites or the International Space Station.

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