The successful destruction of a NASA spacecraft by crashing it into an asteroid on Monday was an important step in the agency’s plan to protect Earth from a potentially devastating asteroid.
The Double Asteroid Redirection Test (DART) spacecraft, weighing in at 1,260 pounds, crashed into the 520-foot-long, 11 billion-pound asteroid Dimorphos about 7 million miles from Earth. The spacecraft crashed around 55 feet from the asteroid’s center.
In order to confirm the collision, the spacecraft’s camera and a shoebox-sized companion, LICIACube, were launched more than a week ago.
“This was an extremely hard technology demonstration to hit a small asteroid we’ve never seen before, and do it in such dramatic fashion,” said Nancy Chabot, a planetary scientist and the mission team leader from Johns Hopkins University.
DART has successfully completed its 10-month, $325 million mission. The asteroid and its close companion Didymos were chosen because they pose no danger to Earth.
In his role as NASA administrator, Bill Nelson said, “There was a lot of inventiveness and creativity that went into this mission, and I believe it will teach us how to one day shield our own planet from an incoming asteroid.” Global cooperation has shown that rescuing Earth is possible.
According to the DART team, the mission was successful since it fell “exactly down the center of what our expectations were,” requiring no course adjustments.
DART successfully collided with Dimorphos, but NASA won’t find out the results for weeks, if not months.
After the impact, “some stuff will likely come out in even days, maybe weeks,” as mission systems engineer Elena Adams put it. In any case, my best guess for a “quantitative full answer” is “a couple of months.”
The agency’s original aim had been to redirect the asteroid’s orbit around Didymos rather than destroy it. At 11 hours and 55 minutes, Dimorphos completes one orbit around Didymos. NASA estimates that this period can be shortened by 10 minutes with the help of the impact.
However, NASA maintains that even a minimal shift of 1% in an asteroid’s orbit might prevent a potentially catastrophic one from slamming into Earth. About 30,000 objects within 120.8 million miles of Earth are considered to be near-Earth objects by NASA. Approximately ten thousand NEOs have been discovered, with the vast majority being about the size of Dimorphos.
Planetary security experts would rather deflect a potentially hazardous asteroid or comet than blow it up and send fragments racing toward Earth if given enough warning. Numerous impactors, or a combination of impactors and gravity tractors, which would use their own gravity to drive an asteroid into a safer orbit, would be needed for huge asteroids.
NASA has assured the public that no asteroid of that size will collide with Earth in the 21st century. However, as of October 2021, only 40% of such objects have been discovered. So far, only a tiny fraction of the millions of smaller asteroids predicted to exist and pose a threat to civilization have been discovered so far.
But astronomers believe that, for the time being, humanity may rest comfortably.
Adams said that the planet’s defense system had passed its initial test. A better night’s sleep would benefit all humans, as the old adage goes.
