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- NASA works with a global coalition of astronomers to find and track dangerous asteroids.
- In the event of an imminent dangerous asteroid impact, NASA already has its plan to alert the public.
When the Chicxulub impactor, a six-mile-wide asteroid, slammed into Earth 66 million years ago, the the dinosaurs had no warning.
If an asteroid that size were to hit Earth today, a shock wave two million times more powerful than a hydrogen bomb would devastate forests and trigger tsunamis. A seismic pulse equal to a magnitude 10 earthquake would crumble cities. And long after impact, a cloud of hot dust, ash and steam would block out the sun, plunging Earth into freezing cold.
But at least we’d probably know it was coming ahead of time. And if NASA has anything to say about it, we might even be able to avoid the apocalypse.
NASA’s Planetary Defense Coordination Office is tasked with find, track and assess risk associated with potentially dangerous asteroids in our solar system.
“We definitely want to find them all before they find us,” he said. Lindley JohnsonProgram Executive Lead of the Planetary Defense Coordination Office.
To do this, NASA works with a global coalition of astronomers called the International Asteroid Warning Network (IAWN).
This is what they would do if an apocalyptic asteroid impact was headed toward Earth.
An international warning system
In the event that a hazardous asteroid is headed toward Earth, IAWN has procedures in place to notify the public.
First, party members who detected the threat would share their observations through the IAWN network to verify their findings and assess the danger.
Once all parties agree that Earth should prepare for impact, NASA will send an alert.
“I don’t have a red phone on my desk or anything like that,” Johnson said. “But we have formal procedures by which a serious impact would be reported.”
If the asteroid were headed toward the United States, NASA would notify the White House and the government would release a formal statement. If it were large enough to pose an international threat, IAWN would notify the United Nations Office for Outer Space Affairs.
On the hunt for asteroids
It is considered an asteroid “potentially dangerous”if it is more than about 460 feet wide and crosses the Earth’s orbit at a minimum distance of 0.5 astronomical units, which is half the distance between the Earth and the sun.
About 2,300 potentially dangerous asteroids are known, and about 153 of them are more than 1 mile in diameter. That’s big enough to trigger a catastrophe if one were to hit Earth.
To find and track them, NASA and the other IAWN partners search for new asteroids in addition to tracking those that have already been discovered. All of your observations are compiled in a database at the Minor Planet Center.
So far, IAWN has found more than 34,000 near-Earth asteroids. With enough observational data, NASA can confidently predict their orbits at least a century into the future, Johnson said.
There is a small chance that the Potentially dangerous asteroid Bennu could impact the Earth in 159 years, causing an explosion equivalent to 24 nuclear bombs. But the odds of that happening are only one in 2,700, according to a 2021 study.
If Bennu is headed toward Earth, NASA has a few tricks up its sleeve to defend our planet.
Defending the Earth
Most of the time, IAWN detects approaching asteroids long before they become an immediate threat to Earth, according to Johnson. But NASA would need at least five to ten years of advance notice to avoid the apocalypse due to an approaching asteroid.
In 2021, NASA launched its first planetary defense test mission. An unmanned spacecraft crashed into an asteroid to divert its orbit from Earth.
The mission was a success and NASA plans to try more deflection techniques in the future. A developing “gravity tractor” technique would send a spacecraft to stay in position next to the asteroid and allow gravitational interaction to pull the asteroid out of its orbit. NASA is also working on a technique that uses an ion beam to change the course of an asteroid.
But if the threat arrived in less than five years, NASA would not have time to divert the asteroid. It could then resort to destruction to minimize and disperse the impact.
If NASA had only had a few months’ warning, then There is not much that can be done to save the Earth..
Fortunately, IAWN’s strategy is to find asteroids decades, if not centuries, before impact.
“That gives us plenty of time to try to do something about it while they’re still in space, so that we completely avoid any catastrophe here on Earth,” Johnson said.