Humanity has made a "significant step forward" in the ability to deflect asteroids that could endanger Earth, according to a new study.
In 2022, NASA intentionally crashed a spacecraft into a "small moon" orbiting a larger asteroid.
The experiment, called Dart, successfully changed the path of the small moon, Dimorphos, around the larger asteroid Didymos.
The mission was hailed as the first successful demonstration of planetary defense, showing that humanity can change the trajectory of an asteroid.
But researchers have now discovered that in addition, both asteroids were deviated from their normal orbit around the Sun.
Analyses showed that Didymos' speed around the Sun decreased by 11.7 micrometers per second due to the collision.
This suggests that in the future, missions could target small moons around large asteroids to change the orbit of the main asteroids.
"This is an important step for our ability to prevent potential asteroid impacts on Earth," the team said.
Researchers from the University of Illinois Urbana–Champaign discovered the difference by analyzing about 6,000 times when Didymos passed in front of a star, blocking its light.
This change – although small – is the first time that a man-made object has accurately altered the path of a celestial body around the Sun.
The change occurred because, although Didymos was not directly hit by Dart, it is gravitationally bound to its small moon. Any change in one asteroid affects the other.
Dr Thomas Statler, lead scientist for small solar system bodies at NASA, said: "This is a small change, but over time, even a small change can turn into a significant deviation."
When Dart hit the small moon, the impact sent a large cloud of debris into space, changed the shape of the asteroid (170 meters wide), and gave an "explosive push" to the moon, shortening its orbit around Didymos by 33 minutes.
This also changed the pair's orbit around the Sun by 0.15 seconds, reducing their orbital speed by 11.7 microns per second, or about 1.7 inches per hour, said Rahil Makadia, lead author of the study, published in Science Advances.
NASA points out that although Didymos was not on course to hit Earth, this change highlights the role that spacecraft – as kinetic impactors – could play in the event that a potentially hazardous asteroid were discovered on a collision course.
The agency is now building the NEO Surveyor mission, a telescope dedicated to planetary defense that will search for hard-to-find objects near Earth, such as dark asteroids and comets that reflect little light.
However, according to Dr Nancy Chabot, planetary scientist and Dart mission manager, there are no other ships like Dart ready to launch immediately in the event of immediate danger.
She mentioned the 90-meter-wide asteroid YR4, which last year had a 3.2% probability of hitting Earth in 2032 – a probability that was then reduced to zero.
"If an object like YR4 were heading towards Earth, we would have no way to actively deflect it right now," she added. /GazetaExpress/
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