What Happens If an Asteroid Comes Too Close to Earth? Don't Panic — NASA Already Has a Plan.

66 million years ago, when an asteroid called Chicxulub crashed into Earth, it wiped away all the dinosaurs and caused a 15-year winter by spewing gases and soot that blocked the Sun. At this time, luckily, humans hadn’t yet evolved in the planetary ecosystem. But today, when more than 8 billion people are roaming the planet, the fear of asteroid collision and subsequent impending doom persistently lingers in the air. Should a gigantic asteroid were to slam into the Earth this time, it would bring about a catastrophic collapse of life. Thankfully, NASA already has its eyes on the skies beyond the orbit. In a 2021 article, a NASA scientist shared its action plan in case of an asteroid threat.

The mission of Dr. Kelly Fast, Planetary Defense Officer for NASA’s Planetary Defense Coordination Office, is to “find asteroids before they find us, in case we need to get them before they get us.” This department of the agency constantly keeps track of asteroids hovering closer to the orbit while also monitoring their orbits far into the future. If they indeed discover an asteroid years in advance, they’d then initiate a “deflective mission” to shoo away the space rock back into space.

One of the most powerful technologies NASA has designed to deflect asteroids is the "Double Asteroid Redirection Test (DART).” DART works on the “kinetic impactor technology” whose goal is to impact the asteroid by adjusting its speed, shape, and path so it is pulled away from the Earth before coming in contact and triggering a deadly blast wave. The first successful demonstration of this technology was observed in 2022 when NASA’s spacecraft rammed into an asteroid named "Dimorphos" when it was 7 million miles away. DART didn’t only shorten the asteroid’s orbit but also altered its shape from a spheroid to a watermelon, ultimately pushing it away. Some of its fragments were blasted and ejected into space as debris.

In case a similar asteroid was to hit the planet today, it would send shock waves that would smash the forests and trigger earthquakes, causing the oceans to flood and cities to crumble. Thick, sooty clouds of dust, ash, steam, and smoke would choke the entire atmosphere, blotting out the Sun and entombing life in a spell of deep freeze. But NASA is confident that “DART will help us better prepare should an asteroid ever be discovered as a threat to Earth.”

The first step of the plan will be executed by a global coalition of astronomers called the International Asteroid Warning Network (IAWN), which would then notify the public about the upcoming hazard. IAWN would assess the scale of danger and accordingly inform people what to do. “I don’t have a red phone on my desk or anything,” Lindley Johnson, Lead Program Executive for the Planetary Defense Coordination Office, told Business Insider. “But we do have formal procedures by which notification of a serious impact would be provided.” If the asteroid was hurtling towards the US, NASA would inform the White House and issue a statement to the public. Whereas, if the asteroid posed an international threat, IAWN would notify the United Nations Office of Outer Space Affairs.

Apart from DART, NASA is also working on other technologies to deflect potential asteroids away from Earth. For instance, there’s a “gravity tractor” under development, which would position a spacecraft next to the asteroid and use gravitational pull to tweak its orbit. Another method NASA scientists are working on is an “ion beam” that would change the space rock’s course in case it attempted to chase Earth.