The flyby on Tuesday of asteroid 2005 YU55, which is the size of an aircraft carrier, has generated excitement among scientists and astronomers.

"A close pass by a near-Earth object the size of asteroid 2005 YU55 is a fairly rare event, something that occurs perhaps once every 25 years or so," said Lindley Johnson, NASA's NEO Observations program executive in the agency's Planetary Science Division in Washington.

The close approach of the asteroid within the moon's orbit will pose no danger, but astronomers say that eventually, one of the numerous asteroids in the galaxy could be a killer asteroid and hit the Earth.

The good thing is, science now knows how to deflect these killer rocks, like the ones believed to have annihilated dinosaurs 65 million years ago.

In an article published at Science.Com, senior writer Mike Wall was able to talk to former astronaut Rusty Schweickart, chairman of the B612 Foundation, a group dedicated to predicting and preventing catastrophic asteroid strikes, who explained the ways of deflecting killer asteroids.

"We have the capability - physically, technically - to protect the Earth from asteroid impacts," Schweickart told Space.Com. "We are now able to very slightly and subtly reshape the solar system in order to enhance human survival," he added.

Schweickart enumerated several different techniques at the disposal of scientists to save the Earth from killer asteroids. Among them:

1. The gravity tractor

According to Schweickart, if a potentially dangerous space rock is detected early on, the best option may be to send a robotic probe out to rendezvous and ride along with it. The spacecraft's gravity would pull the asteroid and over months or years, this "gravity tractor" method would pull the asteroid into a different, more benign orbit.

2. Smashing the asteroid

A more aggressive approach would be to use brute force rather than a gentle gravitational tug. This means slamming a robotic probe into the threatening space rock to change its orbit. According to Schweickart, the impactor approach would not be as precise as the gravity tractor technique but it could still do the job.
There's also the possibility using the nuclear option if the dangerous space rock is too big to knock around with a kinetic impactor, but it would be a weapon of last resort, Schweickart said.

"The potential use of nuclear explosives for deflection cannot currently be ruled out," Schweickart said. "But it is an extremely low probability that they will be needed."

3. 'Mirror bees' and foil wrap

The "mirror bee" concept involves the launching of a swarm of small, mirror-bearing spacecraft to a dangerous asteroid. These mini-probes would aim reflected sunlight at one spot on the space rock, heating it up so much that rock is vaporized, creating propulsive jets.

Bill Nye, executive director of the Planetary Society, said that while concept is not yet ready for deployment or demonstration, he said it can be applied in maybe five years.

According to Nye, another more speculative idea is the possibility of moving an asteroid by wrapping it in reflective foil like a giant baked potato as photons from the sun could nudge the space rock away from Earth.

Scientist, however, said that the biggest key to deflect dangerous asteroids is to detect them with plenty of lead time to take appropriate action, preferably a decade of notice.