Chunks of rock flew off the tiny asteroid Dimorphos when NASA's DART spacecraft deliberately crashed into it in 2022. This, a new study has shown, could have created the first man-made meteor shower known as Dimorphids.
The space agency planned the DART mission, or Dual Asteroid Diversion Test, to perform a full assessment of asteroid deflection technology for planetary defense purposes.
NASA wanted to see if a kinetic impact — such as a spacecraft hitting an asteroid at 13.645 miles per hour (6,1 kilometers per second) — would be enough to change the celestial body's motion in space, it says. N1.
Neither Dimorphos, nor its "bigger brother", known as Didymos, around which it orbits, pose a danger to Earth. Still, the twin asteroid system was the perfect target for testing deflection technology because Dimorphos is comparable in size to asteroids that could threaten our planet.
Astronomers used ground-based telescopes to monitor the impact's aftermath for nearly two years, and found that the DART spacecraft successfully changed the way Dimorphos moves, shifting the lunar asteroid's orbital period (how long it takes to make one revolution around Didymos) by about 32 to 33 minutes.
But scientists also estimated that the deliberate crash created nearly a million kilograms of rock and dust - enough to fill about six or seven wagons. Exactly where all that material will end up in space remains an open question.
Now, new research suggests that fragments of Dimorphos will arrive in the vicinity of Earth and Mars within one to three decades, with the possibility that some debris will reach the red planet within seven years. Small debris could also reach Earth's atmosphere within the next 10 years. The Planetary Science Journal has accepted this study for publication.
"This material could produce visible meteors (also called shooting stars) as they penetrate the Martian atmosphere," said study lead author Eloy Peña Asensio, a postdoctoral researcher in the Deep Space Astrodynamics Research and Technology Group at Italy's Polytechnic University of Milan.
"Once the first particles arrive on Mars or Earth, they could continue to arrive periodically for the next 100 years, which is the duration of our calculations," he added.
Prediction of space debris
The individual pieces are small, ranging from grains of sand to fragments similar to the size of smartphones, so none of the debris poses a risk to Earth, Peña Asensio said.
"They would break up in the upper atmosphere through a process known as ablation, caused by friction with the air at hypervelocity," he said. "There is no possibility that the material from Dimorfos will reach the surface of the Earth," he assures.
But understanding when the debris might reach Earth is more challenging and depends on estimating the speed of the fragments.
When the craft hit Dimorfos, it wasn't alone. A small satellite called "LICIACube" detached from the spacecraft before impact to capture footage of the impact and the debris cloud that followed.
"These key data enabled and continue to enable a detailed analysis of the impact debris," said Peña Asensio.
The research team used data from "LICIACube" and the supercomputer capacity of the Consortium of University Services of Catalonia to simulate the trajectory of the three million particles created by the impact. Computer modeling measured the different possible paths and speeds of particles through the solar system, as well as how the radiation released by the Sun could affect the movement of particles.
Previous studies before the impact suggested the possibility of particles from Dimorphos reaching Earth or Mars, Pena Asensio said, but for the new study, the team limited the simulations to match post-impact data from LICIACube.
The results of the study confirm that if debris were ejected from Dimorphos at a speed of 1.118 miles per hour (500 meters per second), some fragments could reach Mars, while other, smaller and faster movements would travel at 3.579 miles per hour ( 1.600 meters per second) has the potential to reach Earth.
The team said there were still uncertainties about the nature of the debris, but concluded that the fastest-moving particles could reach Earth in less than 10 years.
The authors of the study believe that the possibility of the Dimorphid meteor shower reaching the Earth is unlikely, but they cannot rule it out, said Peña Asensio. And if it does happen, it would be a small, weak meteor shower.
"The resulting meteor shower would be easily identified on Earth, as it would not match any known meteor shower," he said.
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