by About five months after a rocket intentionally crashed into a distant asteroid, NASA has good news: the mission was successful a resounding successand similar methods could prevent Earth from being obliterated by planet-destroying space rock in the future, according to four new studies published in the journal Nature.
“I cheered when DART slammed head-on on the asteroid for the world’s first demonstration of planetary defense technology, and that was just the beginning.” Nicholas Fox (opens in new tab)Deputy Administrator for the Science Mission Directorate at NASA Headquarters, said in a opinion (opens in new tab). “These results add to our fundamental understanding of asteroids and provide a basis for how humanity can protect Earth from a potentially dangerous asteroid by changing its course.”
NASA launched the Double Asteroid Redirection Test (DART) mission in late November 2021 after five years of planning. The goal was to test a theory of planetary defenses called the “kinetic impactor” technique – basically changing an asteroid’s trajectory by having a rocket crash into it at high speed.
In September 2022, NASA’s DART spacecraft successfully collided with the asteroid Dimorphos, a 525-foot-wide (160-meter) “moonlet” orbiting a larger asteroid called Didymos, about 7 million miles (11 million kilometers) from Earth. The force of the impact changed Dimorphos’ orbit around Didymos by about 33 minutes and successfully redirected the smaller space rock’s trajectory, NASA initially reported. (None of the asteroids ever posed a risk to Earth, but the asteroids’ size and shared orbit made them ideal targets for the mission.)
Now, four new studies released on March 1st confirm that the mission was even more successful than NASA engineers originally predicted – and that the kinetic impactor technique is indeed a viable method of protecting Earth from potentially deadly asteroids in of the future is.
The first of the new studies (opens in new tab) details DART’s successful impact with the asteroid, recreating the timeline that led to the impact, the location and nature of the impact itself, and the size and shape of Dimorphos. The successful impact with the asteroid and the resulting change in Dimorphos’ orbit show that “kinetic impactor technology is a viable technique to defend Earth if necessary,” the paper concludes.
The study also notes that intercepting an asteroid roughly the size of Dimorphos without a prior reconnaissance mission is possible, as long as scientists have several years — or preferably several decades — to prepare for the asteroid’s approach.
The second study (opens in new tab) uses two different methods to independently confirm the 33-minute slowdown in Dimorphos’ orbit during the third paper (opens in new tab) calculates the momentum transmitted to the asteroid by the DART spacecraft. The impact immediately slowed the asteroid’s orbital velocity by at least 0.1 inches per second (2.7 millimeters per second), thanks to both the momentum of the falling spacecraft and the huge cloud of dust ejected from the asteroid’s surface after the crash.
That trail of dusty debris has since stretched thousands of miles into space, turning Dimorphos into a little-understood type of asteroid called an “active asteroid” — essentially a space rock that orbits like an asteroid but has a tail like one comet, the thesis (opens in new tab) says. While scientists have previously predicted that active asteroids result from collisions, the transformation has never been observed in real time.
Taken together, these results pave the way for “a bright future for the defense of the planet.” Jason Kalirai (opens in new tab)the director of the civilian space missions division at the Johns Hopkins Applied Physics Laboratory, which jointly manages the DART mission with NASA, said in the statement.
In-depth research into the DART collision continues as planned by the European Space Agency launches its spacecraft Hera 2024 to study the scarred face of Dimorphos up close.
