In the movie Armageddon, the team uses a nuclear blast that supposedly separated a dooms-day sized asteroid. I believe I have found a much safer and more effective way of dealing with an asteroid of this size.
In a certain scenario of finding an asteroid that is on a collision path with Earth, I estimate a time span of 50 years or more of warning. At the minimum of 50 years, us humans would have time to prepare for this event.
Particle Accelerators are an extreme advance in modern science, they take particles and accelerate them to nearly the speed of light. In certain P.A. units, they are set up to create collisions with counter-rotating particles. The biggest P.A. is 17 miles long! When a single collision takes place (2,000-3,000 protons), the energy to melt 1,100 lbs of copper is produced. A current particle colliding machine is capable of producing 600 million collisions a second. The conditions inside of a particle accelerator are space like.
How does the particle accelerator have anything to do with the asteroid?
I propose that mankind develop a particle accelerator that collides atoms in space. Theoretically we can make a section of the accelerator completely open since the conditions inside are the same as space. Create a collision point in the middle of the large gap of the machine.
As the asteroid hurdles towards us, Earthlings would create and place this machine in space directly on the collision course. Since an object in motion stays in motion in space, we would spin this large machine in a rotating manner, such that the particles are able to cover an area wider then the asteroid. Assuming this would take, at the most, 40 years to create and place in space, we would have 10 years to begin accelerating particles and have an adequate amount of particle collisions (>,=600 million) as the asteroid gets near.
As the particle collisions are consistently happening and expelling an enormous amount of energy around the entirety of the asteroid as it passes through the collision field that is constantly rotating, the asteroid would be nearly vaporized as the collisions break apart the asteroid into infinite particles of different elements and space rock (Assuming the initial makeup of the asteroid was iron). As the large cloud of space rock (formally an asteroid) approaches Earth's atmosphere, the enormous amount of bits of asteroid will be burned up in Earth's atmosphere.
The particle collisions actually alter the makeup of the atoms it collides with. If the asteroid was made of iron, it would be collided and the outcome would be several, lighter density, elements. Lighter density would allow the substance to be burned up easier in the atmosphere.