Three years ago, a meteor flew into Earth's atmosphere at around 41,600 miles per hour and exploded 14.5 miles above Chelyabink, Russia. At a width of 59 feet and weighing roughly 11,000 metric tons, it was a big meteor, but not the biggest ever recorded.

The resulting blast was nevertheless about 30 times more powerful than the atomic bomb that destroyed Hiroshima, according to NASA, with an accompanying shockwave that shattered windows in 7,200 buildings. Some 1,500 people were injured.

Now NASA is hoping to avoid a more devastating strike.

On Monday, the space agency opened the Planetary Defense Coordination Office to study how to detect and stop big asteroids and meteors from hitting Earth. (An asteroid is a chunk of inactive rock in space, while a meteoroid is a piece of an asteroid or comet that becomes a meteor when it enters the atmosphere.)

"Asteroid detection, tracking and defense of our planet is something that NASA, its interagency partners, and the global community take very seriously," said John Grunsfeld, associate administrator for NASA's Science Mission Directorate, in a statement. "While there are no known impact threats at this time, the 2013 Chelyabinsk super-fireball and the recent 'Halloween Asteroid' close approach remind us of why we need to remain vigilant and keep our eyes to the sky."

Discovered a few weeks before it flew safely past Earth on October 31 last year, the 1,300-foot-wide Halloween asteroid was the biggest and closest object that flew near the planet in recorded history, according to NASA. It zoomed just slightly past the moon, 238,000 miles away.

Another 2,600-foot-wide asteroid is slated to pass by Earth at around the moon's distance in 2027. For comparison, the asteroid that is believed to have killed off the dinosaurs was a whopping six miles wide and released energy when it exploded that was equivalent to a billion times the energy of an atomic bomb, NASA said.

Stopping this sort of cosmic collision might seem impossible. But experts said it would probably be easier than the ordeal depicted by Bruce Willis in the 1998 disaster flick Armageddon, when astronauts split apart a Texas-sized asteroid using a nuclear bomb.

"The asteroid impact threat on any given day is very very small, but the fact is that asteroids can and will hit the earth," said Bruce Betts, director of science and technology for the Planetary Society. "What makes it different than any large-scale natural disaster is that we can prevent it."

Rather than using a nuke — a last ditch method that could split one big deadly asteroid into many smaller deadly meteors — Betts explained that scientists would likely pummel an asteroid with spacecraft until it veered off its collision course with the planet.

The US and Russia already have the capability of mounting joint asteroid defenses.

"The countries have worked together," said Texas A&M University historian Jonathan Coopersmith, a specialist in space exploration. "You've got the International Space Station as a demonstration of what's possible."

The issue, experts cautioned, is whether scientists can detect the asteroid in time. Mankind could stop almost any asteroid if we had a decade or more of notice, they said.

The nonprofit B612 Foundation, which has raised alarm about the dangers of asteroids since 2002, has proposed building an infrared space telescope to make sure that killer asteroids don't creep up on the planet.

"There are an estimated one million asteroids large enough to destroy a major city, yet thus far we have only tracked about 1 percent of these asteroids," the foundation said in a statement.

But last year, NASA pulled out of a deal with the foundation to help build the $450 million infrared telescope due to a lack of funding.

The Planetary Defense Coordination Office has an annual budget of around $50 million a year. This is not enough to launch anything into orbit, experts said, but is plenty to finance agency scientists working on the ground.

In the event that a killer asteroid comes out of nowhere and NASA doesn't have time to move or destroy it, those scientists would have another function: helping the Federal Emergency Management Agency to coordinate evacuations and deal with the consequences of a catastrophic impact.

Hopefully NASA will put an early warning system in place before FEMA is necessary.

"We don't have to be the dinosaurs," Betts said.