\n A massive space probe could plummet into Earth\u2019s atmosphere as soon as Tuesday evening \u2014 years earlier than expected. And while most of the spacecraft will likely disintegrate in a flaming blaze during reentry, a few components could survive, according to NASA.\n <\/p>\n
\n Early analyses predict the 1,323-pound (600-kilogram) vehicle will strike the atmosphere around 7:45 p.m. ET Tuesday, \u201cwith an uncertainty of +\/- 24 hours,\u201d according to NASA and the US Space Force.\n <\/p>\n
\n The odds that a piece of debris will cause harm to a person is about 1 in 4,200, the space agency said in a news release<\/a>.\n <\/p>\n \n That\u2019s a low chance, according to NASA, and more favorable odds than those of space debris incidents of years past<\/a>.\n <\/p>\n \n \u201cWe\u2019ve had things that have reentered have a 1 in 1,000 chance, and nothing happened; if we have a few that are 1 in 4,000 or 5000, it\u2019s not a horrible day for mankind,\u201d said Dr. Darren McKnight, a senior technical fellow at space-tracking company LeoLabs.\n <\/p>\n \n But this risk is decidedly higher than some other notable events \u2014 including the 2018 reentry of China\u2019s space station<\/a> that put parts of the world on edge. The chance of debris hitting a human in that scenario was estimated to be less than one in a trillion, and no one was ultimately harmed.\n <\/p>\n \n The spacecraft currently in question is the now-defunct Van Allen Probe A, which NASA launched alongside a twin vehicle in 2012 to study the two cosmic bands of high-energy particles that are trapped in Earth\u2019s magnetic field at altitudes ranging from about 400 to 93,300 miles (640 to 58,000 kilometers.\n <\/p>\n \n \u201cThe belts shield Earth from cosmic radiation, solar storms, and the constantly streaming solar wind that are harmful to humans and can damage technology, so understanding them is important,\u201d NASA said in a Tuesday statement. The Van Allen probes mission \u201cmade several major discoveries<\/a> about how the radiation belts operate during its lifetime, including the first data showing the existence of a transient third radiation belt, which can form during times of intense solar activity.\u201d\n <\/p>\n \n The Van Allen Probe A \u2014 along with its twin, the Van Allen Probe B \u2014 studied the radiation belts for years longer than expected before concluding their mission in 2019 when the vehicles ran out of fuel.\n <\/p>\n \n From the outset, NASA intended to dispose of the radiation-studying spacecraft by allowing them to burn up in the atmosphere as they plummeted to Earth. It was understood that a fiery cauldron of physics would likely reduce the probes to trace fragments by the time they reach the ground.\n <\/p>\n \n Mission planners mapped<\/a> out the probes\u2019 return home when the spacecraft concluded its mission \u2014 conducting a few maneuvers designed to expel any remnants of fuel and confirm that the vehicles were in a position for atmospheric drag to slowly pull them out of orbit. That ensures the defunct spacecraft aren\u2019t left to spend eternity flying uncontrolled through Earth orbit, where they could run the risk of colliding with active satellites or habitats such as the Internaitonal Space Station.\n <\/p>\n \n Initially, NASA predicted the spacecraft would return home in 2034.\n <\/p>\n \n \u201cHowever, those calculations were made before the current solar cycle, which has proven far more active than expected. In 2024, scientists confirmed the Sun had reached its solar maximum, triggering intense space weather events,\u201d NASA said in a Tuesday statement. \u201cThese conditions increased atmospheric drag on the spacecraft beyond initial estimates, resulting in an earlier-than-expected re-entry.\u201d\n <\/p>\n \n The Van Allen Probe B is also now on track to be dragged out of orbit before 2030.\n <\/p>\n \n The space agency\u2019s policies require that vehicles launched by the US reenter or be safely disposed of within 25 years<\/a> of the mission\u2019s end. Safe disposal can include deorbiting the spacecraft or positioning it in a graveyard orbit, or an area of space designated for abandoned spacecraft to linger in orbit.\n <\/p>\n \n Graveyard orbits have their own issues, noted McKnight. Leaving a spacecraft in one doesn\u2019t completely alleviate the risks of in-orbit collisions, and any run-ins present the possibility of junk spewing into other areas where active satellites are operating.\n <\/p>\n \n In the case of the Van Allen Probes, reaching a grave yard orbit also would have expended precious fuel that was used to gather additional science.\n <\/p>\n \n In recent years, there have been calls<\/a> from inside and outside NASA warning about the growing risks of spaceborne debris.\n <\/p>\n \n \u201cThere\u2019s been a lot more awareness of the importance of this issue,\u201d said Marlon Sorge, a space debris expert with the federally funded research group The Aerospace Corporation. Since the Van Allen probes were launched in 2012, \u201cin that time there\u2019s been increasingly more awareness of the need to try to mitigate what survives to the ground.\u201d\n <\/p>\n \n It\u2019s possible, Sorge said, that NASA may have designed the mission differently if it launched today \u2014 perhaps aiming to ensure no piece of the vehicle would survive reentry as many modern satellite operators do.\n <\/p>\n \n As the cost of spaceflight has been steeply reduced in the last couple of decades, the space debris issue has grown in scope and scale.\n <\/p>\n \n Recent headline-grabbing incidents have included a piece of garbage jettisoned from the International Space Station that unexpectedly survived reentry<\/a> and pierced the roof of a home in Florida in 2024. Pieces of hardware from private rocket companies, including SpaceX and Blue Origin, have also turned up on beaches<\/a> and private property<\/a> across the world.\n <\/p>\n \n Such instances are actually fairly common, noted McKnight.\n <\/p>\n \n \u201cWe get about one object a week \u2014 a dead rocket body, another payload that isn\u2019t maybe as high a profile as this. So that happens about once a week that some mass will survive to the ground,\u201d McKnight said.\n <\/p>\n