If the dinosaurs had a space program or enough technological prowess, they would be alive today! Unfortunately for them though, they were wiped off the face of the planet as they had none.
Some 66 million years ago, Chicxulub, an asteroid 6-9 miles in diameter struck the Earth kickstarting a mass-extinction event that caused around three-fourth of the living creatures to die off.
If such an asteroid impact were to happen today, the results would be no different. What is scarier is that even with all our technological advancements and knowledge about asteroids and their trajectories, many of them pass by Earth every year without us having a clue that they were going to.
What if we miss a large one and it's too late? Well, frankly, there is nothing that can be done about it. But for the ones we know are coming, or for the ones that could give only a moment's notice, we should be utterly prepared. Thankfully we have some ways to deal with such asteroid impact threats.
This is a measure that is being looked at seriously by the various sapce agencies of the world. As the word suggests, this method requires an unmanned space probe to gently nudge an asteroid headed towards us so that over time, it's trajectory would change just enough so as to miss us.
Alternatively (and more realistically), a high energy impact where the space probe crashes into the asteroid could produce the same results too. The only thing to be careful about here is to not cause the asteroid to break apart in multiple chunks.
Of course, we would need to know about such an asteroid years in advance so that the space probe could be prepared and launched and that it could reach the asteroid in time to cause a deflection that is just enough.
This might sound like the easiest, fastest and safest method and that is because we have been watching way too many movies. The concept is simple - launch a nuclear missile at an incoming asteroid and it would pulverize it. But the reality is not that simple.
Although we would require much less time to pull this off compared to the first option, there is a greater chance that we would simply break it into a lot of smaller pieces. These smaller pieces, while still not enough to cause a global extinction event, could end up destroying a large number of cities and cause enormous harm to life and property.
Other "Out There" Suggestions
There is no dearth of suggestions from the scientific community on how to deal with a killer asteroid but many of these sound too "out there". Some sound almost impossible in the near future and some not too effective.
Suggestions have ranged from attaching an asteroid with a solar sail so that it could be deflected by solar radiation, to let a space probe orbit it so it could cause enough gravity pull to change its trajectory.
One particular way that sounds relatively impossible right now but could become a viable option as technology advances in the coming decades, is to send a spacecraft with powerful engines that would attach itself firmly to the asteroid. Then it would fire off its powerful engines to a slightly different angle than the original trajectory which would on a longer time frame, change it significantly.