Debris from the impact of NASA's DART spacecraft with the asteroid Dimorphos could reach Earth and Mars, astronomers have concluded. While the debris could produce meteors on Mars, it's unlikely we'll see a meteor shower on Earth.
DART, the Double Asteroid Redirection Test, bumped into Dimorphos on September 26, 2022, with the intention of testing whether a kinetic impact could one day push the orbit of a potentially hazardous asteroid away from Earth. The test passed with flying colors: Dimorphos was pushed into a shorter path around its parent asteroid, Didymos(Neither Dimorphos nor Didymos ever posed a threat to our planet; they were merely guinea pigs in this test.)
The impact, which carved a crater into Dimorphos, also threw out a large amount of debris. This ejecta formed a cone of escaping material that was observed up close and personal by a small cubesat called LICIA Cube (Light Italian Cubesat for Imaging of Asteroid), which hitched a ride on DART to view the aftermath of the impact. In particular, LICIACube observed particles of a micron (one millionth of a meter) and larger, which were ejected at speeds of up to 500 meters (1,640 feet) per second.
Meanwhile, the Large Array Survey Telescope (LAST) and the 28-inch telescope at the Wise Observatory, both in Israel, as well as NASA Fast The satellite's ultraviolet and optical telescopes suggested that even more microscopic particles were released, traveling much faster, between 1,400 and 1,800 meters (about 5,000 to 5,900 feet) per second.
Related: NASA's DART asteroid crash really messed up its space rock targetA team led by Eloy Peña-Asensio of the Politecnico di Milano in Italy and Michael Küppers, who is a project scientist for the European Space Agency Hera Follow-up mission to DART, due to launch to Didymos and Dimorphos in October, has now modelled how that debris will spread across the interior solar system. The team's calculations are based on the extent to which the gravity of Didymos and Dimorphos, the sun, Mercury, VenusEarth, Mars, Jupiter as well as the moon all affect the trajectory of the debris.
Their main simulation modeled 3 million particles, divided into size groups of 10 centimeters (3.9 inches), 0.5 cm (0.2 inches) and 30 microns with speeds up to 500 meters (1,640 feet) per second, based on observations from LICIACube.
"Our findings indicate that, given the geometry of the ejecta cone and the observed maximum ejecta velocity, there are plausible pathways for this material to reach Mars," Peña-Asensio told Space.com. "This is our most confident conclusion."
A second simulation was modeled around the higher ejecta velocities suggested by Swift and the ground-based observatories.
"For the second simulation, these faster ejecta are expected to consist mainly of particles smaller than a micrometer. These particles would not generate meteors if they entered the atmosphere."
Crucially, the main simulation showed that the slower-traveling particles could reach Mars within 13 years of the DART impact, meaning by 2035. Their delivery to the Red Planet is aided by the fact that the Didymos-Dimorphos binary star's orbit around the Sun crosses Mars' orbit. That means the ejecta don't have to travel as fast or far to reach Mars as they do to reach Earth. In fact, the main simulation showed that none of these slower-traveling particles will reach Earth.
The second simulation, however, is a different story. It implies that fast-moving ejecta could arrive on Mars within 5 years of the DART impact, and as early as 7 years after the impact with Earth, in 2029. But given the small size of these particles reaching Earth, they would not create a visible meteor shower. This would only happen if larger particles somehow managed to slip through.
"In our main simulation, no particles reach Earth with speeds up to 1,000 meters (3,280 feet) per second," Peña-Asensio said. "Only particles emitted with speeds of 1,500 meters (4,900 feet) per second or higher reach Earth, and this happens exclusively in the secondary simulation."
"However," the researcher added, "if these particles were slightly larger or if LICIACube missed macroscopic particles at these velocities, it would be possible that they reach Earth and produce observable meteors. Only future meteor observation campaigns can verify this."
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The simulations were even able to show where the ejecta that hit Earth and Mars would come from. The debris that could cause a Martian meteor shower in 2035 would come from the northern part of the impact site, while the smaller, fast-moving particles that could reach Earth would come from the southwestern part of the resulting crater.
"Impacts like DART and the resulting ejecta highlight the ongoing exchange of material between planetary bodies, asteroids, comets and other celestial bodies," Peña-Asensio concluded.
So while Earth's skies probably won't be lit up by a meteor shower from Dimorphos' debris, Mars rovers could well enjoy shooting stars in the next decade.
The research is available as a preprint on the arXiv paper repository.
