At last count, there were over a thousand near Earth asteroid. If this was not scary enough, did you know that in nineteen hundred eighty nine, a massive asteroid missed us by just six hours and we did not knew about it after it crossed the earth orbit.

Everything happens at an incredible scale, but also at incredible slow rates. If you consider that distance more than two hundred million kilometers, pin pointing a tiny rock at that scale in space is an almost impossible task, and even if we had a thousand of such asteroids hurtling towards us.

We could be none the wiser unless we knew exactly where to look. Now-a-days we could in theory, plot the course, predict the time of an impact of an Earth-bound asteroid by as much as few decades in advance.

The truth is that a lot of asteroids that we are aware of are actually just amalgamations of debris, vast clumps of boulders and dust and are mostly just empty volume. Such imaginative ideas as solar sails won’t work and we would have to try something as exotic s gravity tethers.

Another aspect to consider is that while an asteroid might seem to be very hard, many are actually is hollow and may even have vast quantities of ice. There are primarily two things you do to an asteroid, destroy it or deflect it and what we chose to do depend upon the size and composition of asteroid.

The reason we need this is because if we have to slow down or destroy a massive asteroid , we need to launch platform for the launch of projectiles at a massive scale if we even hope to do anything to an asteroid.

A more feasible or a long term plan involves the placement of a sufficiently large spacecraft or artificial moon near enough to such an asteroid that the gravitational attraction between the two will be enough to change the trajectory of the cluster.

Most planets when formed were literally the molten balls of fire. Asteroids might prove to be the answer as to how water actually made its way back to planets such as ours.