Can we protect Earth from an asteroid speeding toward us?
Universe

Can we protect Earth from an asteroid speeding toward us?

The Chicxulub crater, which impacted the Yucatán Peninsula 65 million years ago, is the most famous asteroid to hit with Earth. It is infamous for eradicating the dinosaurs as well as three-quarters of all life on Earth. Other massive craters, such as the Vredefort crater in South Africa and the Sudbury Basin in Ontario, Canada, were likely even larger and barreled toward us billions of years ago.

Meteoroids, the smaller cousin of asteroid, have hit us in recent years. Tunguska struck Siberia in 1908, lighting up the sky as far away as London, and Chelyabinsk, another Russian hit, was seen on video in 2013.

A major earthquake hasn’t impacted us in a long time, but the next one is unavoidable, according to Nancy Chabot, a planetary scientist at Johns Hopkins University. “While there’s currently no known asteroids that are on track to hit us in the foreseeable future, asteroids have been hitting the Earth for billions of years and it’s really a cosmic inevitability,” says Chabot.

But what happens when a massive object speeds at us? Will we be aware of it in advance, and will we be prepared to defend ourselves?

Tracking asteroids

According to Chabot, astronomers are already tracking over 90% of the larger asteroids (one kilometer or larger) using Earth-based telescopes that take several images over several nights. They then plotted their orbit. We can monitor asteroids for decades or perhaps centuries if we track them. None of these are a threat right now.

Experts in planetary defense, on the other hand, are far more concerned about smaller objects, a few hundred meters or more in size. These asteroids might cause significant damage to the globe, yet we’re only tracking around half of them, according to Chabot. They’re smaller and thus more difficult to find. While the objects we know about are not now a threat, there is a vast universe of undiscovered asteroids and comets that could hit the planet with little warning.

“If something in that smaller size hit the Earth, it wouldn’t necessarily be an extinction level event, but it would be a regional devastation,” says Chabot.

NASA’s next big planetary defense project, she says, is to launch a telescope into space that is  “good at finding asteroids,” An IR telescope, or infrared telescope, could detect infrared radiation and locate these smaller, darker objects hidden deep in the night sky.

“Most telescopes that we put in space are designed to look at things really far away, but these objects are very close to Earth in our solar system so they move really fast. This telescope would have to be good at looking at things nearby,” says Chabot.

Intercepting asteroids

We’ll have plenty of warning time if asteroids are traveling towards us once we know where they are. That’s where NASA’s most recent planetary defense experiment, the Double Asteroid Redirection Test (DART), comes in. DART is an autonomous rocket that can push or deflect asteroids to gently alter their trajectory, preventing them from colliding with the globe. DART uses “kinetic impact technology,” which involves crashing a spaceship into an object to gently redirect its orbit, according to Chabot. DART launched in November and will arrive at the Didymos asteroid system in September. It will put its deflecting technology to the test on a 160-meter-wide asteroid.

However, DART only works if you have enough notice time to launch your rocket into space and begin pushing it. What happens if we miss the window and it collides with the planet?

At the University of California, Santa Barbara, Phillip Lubin specializes in planetary defense. His most recent research displays a technology called Pulverize It (PI), which would use “penetrator rods” to break the asteroid into pieces small enough to burn up before impacting Earth. If it was a “planet-killer” sized asteroid, nuclear-capable interceptors would have to break it up and distribute the bits. All the while they were far enough away to avoid colliding with the planet.

Finally, we must determine the location of items and the feasibility of intercepting them in order to nudge or break them apart. But, according to Lubin, we’re not there yet. We may have the technology to stop the majority of threats, but we are still in the “detailed analysis and simulation phase.”

“Humanity does not currently possess a robust planetary defense program — period. We’re largely tracking threats and hoping that they don’t hit us,” says Lubin.

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