GabyOn September 26, 2022, NASA’s DART spacecraft deliberately struck Dimorphos, the small moon of asteroid Didymos, to change its orbit.
According to NASA, the DART (Double Asteroid Redirection Test) mission was “the first in history dedicated to the study and demonstration of one method of asteroid deflection — altering its trajectory through a kinetic impact.” The mission showed that kinetic impact can be a viable strategy for protecting Earth from potentially hazardous asteroids (PHAs).
Dimorphos is a small moon that orbits the larger asteroid Didymos.
Although NASA demonstrated the possibility of changing an asteroid’s trajectory, the kinetic impact also produced debris that could travel to Earth and other bodies in the solar system.
In a recent study, an international team examined how that debris could reach Earth and Mars, and the outlet ScienceAlert reported on their findings. After running a series of dynamical simulations, the scientists concluded that some asteroid debris could reach Mars and the Earth–Moon system within a decade.
Potentially hazardous asteroid fragments
The research team was led by Dr. Eloy Peña-Asensio, a researcher at the Group for Research and Technology in Astrodynamics of Deep Space at the Polytechnic Institute of Milan. He was joined by colleagues from the Autonomous University of Barcelona, the Institute of Space Sciences (ICE-CSIC) of Spain, the Catalan Institute for Space Studies (IEEC), and the European Space Agency (ESA).
For their work, the team relied on data from the lightweight Italian CubeSat for asteroid imaging (LICIACube), which accompanied the DART mission and observed the kinetic impact.
That data let the researchers constrain the initial conditions of the ejection, specifically the debris trajectories and speeds — from several dozen meters per second up to about 500 m/s. They then used supercomputers at the navigation center and NASA’s Navigation and Ancillary Information Facility (NAIF) to model what would happen to the debris over time.
The simulations showed that some particles, ranging in size from 30 microns to 10 centimeters, could reach Earth and Mars within a decade or longer, depending on their ejection speed.
For example, particles ejected below 500 m/s could reach Mars in roughly 13 years, while particles ejected above 1.5 km/s could reach Earth in about seven years. Still, the models suggest it’s more likely to take around 30 years before any fragments arrive at Earth.
“If these fragments of Dimorphos come close to Earth, they will pose no danger,” Dr. Peña-Asensio reassured. Because of their small size and high speed, they would burn up in the atmosphere.
Michael Kuipers, a research associate on the Hera project at the European Space Agency (ESA), said “a unique aspect of the DART mission is that it is a controlled impact experiment, meaning that the properties of the impactor (size, shape, mass, speed) are precisely known.”
Kuipers added that knowing those properties “allows us to test and improve our models and the scaling laws of the impact process and the evolution of the ejection.” Scientists hope to learn as much as possible soon about the risks and implications of planetary-defense strategies aimed at protecting Earth.
The study has been accepted for publication in The Planetary Science Journal.
