ESA Plan to Deflect Asteroid
NASA Articles 8/21/11
By: Chris Capps
There are very few likely events in Earth's future more dangerous to life on our planet than the possible collision of a massive asteroid. Even an Earthbound object only a few hundred meters in diameter could cause significant damage to an area interrupting power supplies, destroying necessary infrastructure, and affecting the lives of millions in the process. But the European Space Agency's ambitious Don Quijote plan is designed to impact significantly larger targets heading toward Earth.
The project involves launching a massive spacecraft into orbit around the planet and then having it wait there in orbit until a significantly dangerous target (an asteroid) is seen by NASA or astronomers on the ground. Once the object is spotted, the spacecraft is remotely started by ground control and set to launch into the target. A small observation probe is launched at the asteroid and it matches the object's speed, orbiting it directly and sending back information on its mass, its density, its shape, and its general speed as it hurtles toward Earth. From that point personnel can study the best course of action and launch the Don Quijote at the rock. But launching any ordinary spacecraft at an incoming asteroid would likely barely impact the incoming rock, so this one is to be specially designed to have as much mass as possible and achieve the exact speed necessary.
The amount of damage an object hitting another object can do is largely dependent on the amount of mass the striking object has coupled with its speed. There are other factors involved, such as the integrity of the object's structure. For example, a water balloon will barely hold together if throwing it at another object. On the other hand a frozen water balloon has significantly more structural integrity and would have a much larger impact - quite literally.
But is the Don Quijote project overly ambitious? Are we looking at a project that would cost more than it was worth? In the past 100 years we have been made aware of several objects that came dangerously close to Earth, but did not impact it. And as we continue to look into the heavens the psychological effect of knowing most Earthbound objects can be deflected would be of immeasurable comfort to some. But how likely is it really? The answer may surprise you.
Every year asteroids measuring between five and ten meters enter our atmosphere. While a rock of a similar size would be safe standing still on the ground, the incredible speed of these objects often explodes with as much force as the atomic bomb dropped on Hiroshima, little boy. If such an object were to survive its descent and hit an area of land the size of a small town it could wipe it out with the force of fifteen thousand tons of TNT, although this is generally considered unlikely.
But go down the timeline 800 years and you'll find a likely candidate in the future that should be watched and prepared for. A massive asteroid measuring just over a kilometer in size - 1950DA is a very real possibility for impact if it is not deflected or destroyed before then. Of course in 800 years, science may consider the object no problem at all.