NASA satellite to fall back to Earth, with a small risk of debris
A former NASA satellite, launched 14 years ago to study Earth’s radiation belts, is expected to crash into the planet on Tuesday.
The approximately 1,323-pound spacecraft, known as Van Allen Probe A, is expected to plunge into the atmosphere around 7:45 p.m. EDT, based on U.S. Space Force forecasts. Although it will be an uncontrolled re-entry — meaning NASA has no way to steer the probe — the agency expects most of the satellite to burn up during its fiery journey through the atmosphere.
The agency, however, said in a statement that “some components are expected to survive re-entry.”
“The risk of harm to anyone on Earth is low – about 1 in 4,200,” NASA said. “NASA and the Space Force will continue to monitor re-entry and update forecasts.”
It is not uncommon for disabled satellites, spent rocket parts and small space debris to fall back to Earth. In fact, these types of objects re-enter the planet’s atmosphere almost daily, according to the European Space Agency.
In most cases, the material burns harmlessly in the atmosphere, but occasionally some parts survive. Even then, it is rare for space debris to fall onto land and cause damage, as oceans cover about 71% of the Earth’s surface.
It can be difficult to accurately predict when and where an out-of-control spacecraft will fall back to Earth, because the process is influenced by atmospheric dynamics, space weather, and the positioning of the probe as its orbit deteriorates. The Space Force’s forecast for the timing of the Van Allen A probe’s reentry includes an uncertainty of plus or minus 24 hours.
The Van Allen A Probe – along with its twin, the Van Allen B Probe – were launched into space on August 30, 2012. The pair was designed to fly past and study rings of high-energy radiation particles trapped by Earth’s magnetic field. These enormous donut-shaped areas make up the planet’s permanent radiation belts, called Van Allen belts.
The Van Allen belts protect Earth from solar storms, cosmic radiation, and constant waves of charged particles known as solar wind. Without them, high-energy solar radiation particles could bombard orbiting satellites, harm human health and destroy ground-based power grids. But astronauts must cross the Van Allen Belts to reach space, which exposes them to harmful radiation.
The Van Allen A and Van Allen Probe B were developed to better understand belts and their origin. The mission made many discoveries about the characteristics and composition of radiation belts and even discovered a third “transient” radiation belt that can form during periods of intense solar activity.
The twin probes operated until 2019, when they ran out of fuel. NASA ended the mission after that, and they’ve been languishing in orbit ever since.
NASA originally thought the two probes would re-enter Earth’s atmosphere in 2034, but higher-than-normal solar activity in recent years has increased atmospheric drag on the probes. When the sun is more active and releases more energy, it increases density in parts of the atmosphere, which can slow down satellites or degrade their orbits.
However, the Van Allen B probe is not expected to reenter the Earth’s atmosphere before 2030.
Such satellite reentries highlight the broader problem of space debris, especially as launches become more frequent. Tens of thousands of pieces of space debris – and millions of other smaller orbital debris – are crowded in low-Earth orbit, the narrow band of space around the planet where many communications and GPS satellites operate.
Space debris is flying into orbit at up to 18,000 mph, threatening to collide with an operating spacecraft and posing safety risks for astronauts on the International Space Station.
