Asteroid Dimorphos as seen by the DART spacecraft 11 seconds before impact
NASA/Johns Hopkins APL
NASA tried to slam a spacecraft into an asteroid in 2022 to get it moving, but the collision had more than expected effects on the asteroid’s trajectory. An analysis of the smash-up and its aftermath may reveal why, and the results may tell us even more about how to protect Earth from asteroids.
The Double Asteroid Redirection Test (DART) sent a probe cairning to a small asteroid called Dimorphos orbiting a larger asteroid called Didymos. Five research groups analyzed different aspects of the collision and found that Dimorphus was closer to Didymos, all trajectories about 33 minutes shorter than before the collision. This is more than 25 times the orbital period change required for the mission to be considered successful. .
That was helped by the fact that DART was spot on. “The spacecraft hit very close to the center of Dimorphus, which is where we want to hit to maximize momentum transfer,” says Carolyn Ernst of Johns Hopkins University in Maryland. .
But perhaps more importantly, part of the asteroid flew away after impact and was pushed further up. “People might think of the DART mission as a fairly simple experiment, akin to playing billiards in space. One solid spacecraft he hits one solid asteroid,” says Northern Arizona University. Christina of his Thomas says. “But asteroids are much more complex than just solid rock.”
After all, most asteroids, including Dimorphus, are heaps of rubble tenuously held together by gravity. So when DART hit, 0.3-0.5% of the asteroid’s mass was ejected into a giant ejecta. This plume amplified the momentum transferred from the spacecraft to the asteroid by a factor of 3.6.
If you need to use something like DART to deflect an asteroid heading towards Earth, you need to understand that the extra push will be important. “Ejecta will put more pressure on the asteroid than the spacecraft itself. ,” says Jian-Yang Li of the Institute for Planetary Science in Arizona.
The ejecta plume also places Dimorphus in a strange category of asteroids called active asteroids with comet-like tails. It has long been thought that these tails could form from collisions with smaller cosmic rocks, and DART has shown that idea fits nicely. We can pinpoint exactly what’s going on with asteroids, which helps us understand what they’re made of, which has implications for the birth of the solar system when they formed,” said the SETI study. says Ariel Graykowski of California.
We know that after DART we can change the orbits of smaller asteroids like Dimorphus, but since asteroids are all different, would a similar mission work against anything that might be headed in our direction? “I think the best way to apply what we’ve learned is to apply it again to something bigger,” says Graykowski. “We need to take advantage of what we know about how mushy the asteroid ended up being, how much material it ejected, how much it could move, whether it could be scaled up and started all over again. there is.”
Journal reference: NatureDOI: 10.1038/s41586-023-05805-2, DOI: 10.1038/s41586-023-05810-5, DOI: 10.1038/s41586-023-05811-4, DOI: 10.1038/s41586-023-05878-z, DOI : 10.1038/s41586-023-05852-9
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