How to Save the Earth From an Asteroid? Tie It Up!

Done right, `you change the object`s orbit and allowing it to pass by the Earth,` said David French.

An asteroid is hurtling toward the planet and threatens to destroy life as we know it. What can humankind do, other than cower?

Tie the thing down, suggests aerospace engineer David French of North Carolina State University.

He has proposed a way to divert asteroids and other threatening objects by attaching a long tether and ballast.

Done right, "you change the object's center of mass, effectively changing the object's orbit and allowing it to pass by the Earth, rather than impacting it," French said in a statement.

In March an asteroid passed by Earth at a distance of just about 49,000 miles (79,000 kms).

NASA's Near Earth Object Program has identified more than 1,000 "potentially hazardous asteroids." None is on a collision course with Earth but asteroids have struck before and almost certainly will again, scientists agree.

"For example, about 65 million years ago, a very large asteroid is thought to have hit the Earth in the southern Gulf of Mexico, wiping out the dinosaurs, and, in 1907, a very small airburst of a comet over Siberia flattened a forest over an area equal in size to New York City," French said.

"The scale of our solution is similarly hard to imagine."

His idea, to be presented in September at an American Institute of Aeronautics and Astronautics conference, calls for using a tether somewhere between 600 miles (1,000 km) and 60,000 miles (100,000 kms) long to change the trajectory of any object headed toward Earth.

"Nuclear weapons are an intriguing possibility, but have considerable political and technical obstacles. Would the rest of the world trust us to nuke an asteroid? Would we trust anyone else?," French asked. "And would the asteroid break into multiple asteroids, giving us more problems to solve?"

Other solutions that have been proposed include crashing a spacecraft into the asteroid, focusing the Sun's energy to deflect it, or using a laser to break it up.