How to deflect an asteroid hurtling toward Earth

Karen Norris/Staff

A massive space rock enveloped in fire and hurtling toward Earth at warp speed may be something we’ve only seen in movies. But asteroids do collide with planets all the time – including our own.

Most of what hits Earth is small and burns up in the atmosphere. But something the size of a football field plunges through the atmosphere and causes local damage every 2,000 years or so. And once every few million years, a space rock big enough to cause global devastation hits. 

So what would we do if scientists identified a big one on a collision course with Earth? Although humans have never deflected an asteroid before, there are plenty of ideas. 

Why We Wrote This

Asteroids collide with planets all the time, so scientists at NASA are working to prepare for the unlikely possibility of a major collision.

The National Aeronautics and Space Administration (NASA) may actually test a possible solution for the first time soon. The Double Asteroid Redirection Test (DART), as the mission is called, moved to the preliminary design phase in June.

It would use a technique called the “kinetic impactor” to change the speed of an asteroid ever so slightly. Think of it this way, explains Lindley Johnson, NASA’s planetary defense officer: If two cars are driving on a highway side by side at the same speed and they have to merge into one lane, they will collide unless one vehicle changes how fast it is going. Earth and an asteroid are the two cars. 

What NASA wants to do is see if it can change the velocity of the rock to prevent it from smashing into Earth. If the DART mission gets the full go-ahead and funding, it would test this technique by slamming a spacecraft into an asteroid in orbit around another asteroid. Should that prove successful, the idea would be to apply the same concept to a rock orbiting the sun that is on a trajectory to hit us. 

Among other ideas to avoid an asteroid Armageddon:

The gravity tractor. A spacecraft would station itself alongside the asteroid and, over time, the gravity of the probe would tug the asteroid into a slightly different orbit. 

The hair dryer effect. This would involve using some heat source, such as lasers or sun reflected off a solar mirror, to evaporate material from one spot on an asteroid, creating a sort of propelling jet that would alter the rock’s orbit.

 Nuclear explosion. This would not be like what people see in the movies, Mr. Johnson says. Scientists wouldn’t send up a bomb to incinerate an asteroid. It would be something much more modest and targeted – a bomb strike intended to take just enough material off a space rock to alter its path. Still, Johnson adds, if they were out of time, scientists could try to blow up the asteroid. But pieces would likely still rain down on the planet.

Celestial graffiti. Since solar radiation gives small bodies a bit of a nudge in orbit, scientists could change an asteroid’s trajectory by painting it white or black. 

“The key to all this is finding [potentially dangerous asteroids] as early as we can,” Johnson says. Given enough time, these technologies could be tested, or new ones dreamed up.

This article first as a sidebar to the Monitor cover story Chasing Asteroids.

You've read  of  free articles. Subscribe to continue.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to CSMonitor.com.

QR Code to How to deflect an asteroid hurtling toward Earth
Read this article in
https://www.csmonitor.com/Science/2018/0817/How-to-deflect-an-asteroid-hurtling-toward-Earth
QR Code to Subscription page
Start your subscription today
https://www.csmonitor.com/subscribe