Insurrections occur, wreaking havoc within countries and plaguing them with poverty and destitution. Earthquakes rattle and thrash cities; leaving them strewn with carnage and destruction. And perhaps most importantly, the perpetual threat of nuclear fallout, one that could endanger all of our lives. And yet, despite the apprehension and omnipresent dread that lingers within us due the prospect of such catastrophes, the most perilous and fatal menace is one that we are utterly oblivious to; one that does not even originate from this planet, but from a celestial source.

 

We have all at some point or the other gazed upon the nighttime sky with awe and reverie. We have gawked at the vastness and unknowns of space, pondering the vagaries of this massive entity. We look at the glimmering stars, the radiant moon, and if we are fortunate, catch sight of a glaring comet that streaks through the sky. Comets are refuted as a dazzling and mesmerizing phenomenon; however a scarcity of people are aware of the grave dangers that these seemingly harmless rocks could poise for the earth. In truth, comets are a substantially smaller version of asteroids, behemoth celestial rocks that travel through the abyss of space. And it is asteroids that could pose a dire threat to life on earth.

      

There are millions upon millions of asteroids passing through space, ranging from meager boulders of tens of meters to colossal sub planets with diameters of nearly 1000 kilometers. Occasionally an asteroid traversing through the realms of space passes too close to a planet and gets caught up in its gravitational field. The exerted gravitational pull of the planet in turn causes the asteroid to deviate from its linear trajectory and follow a curvature path that possibly sets it on a collision course with the planet. 

      

Despite the vastness of space, asteroid impact is a prevalent occurrence. Stony asteroids with a diameter of 4 meters impact the Earth approximately once a year. Whilst asteroids of smaller proportions(less than 1 meter in diameter) - also referred to as meteoroids- enter the vicinity of the earth’s atmosphere at a rate of 500 per year. Due to their scant size, however, they are predominantly burnt up by the earth’s atmosphere, and fail to reach the surface of the earth. Nevertheless, asteroids poise an impending threat, one that became evident in the Chelyabinsk meteor airburst in Russia which injured over a thousand people.

      

The planet Earth has undergone periods of abrupt and catastrophic changes, many of which are directly attributable to large asteroid impacts. Perhaps the most noteworthy and prominent impact event is the Cretaceous-Paleogene extinction event, which occurred 65 million years ago and led to the extinction of the dinosaurs. 

Another event is the Permian-Triassic mass extinction, which is directly associated with an asteroid collision, and causedthe wipe out of 90 percent of all living species at the time. Large collisions occur seldom-approximately every 20 million years- but when they do, the ratifications are utterly devastating and catastrophic. 

      

The human civilization is at a pinnacle of growth and sophistication. Constant advancements in technology are made, paving the way for modernity and convenience; whilst profound ameliorations in the field of medicine have contributed to the alleviation of diseases and protraction of life spans. Overall, the world has never been as interconnected and integrated as it is today and the fundaments of human civilization have never been as firm and steadfast as now. 

      

Ironically however, the world as we know today is in a state of vulnerability. Our inordinate reliance and dependency on technology and modern conveniences has left us in a prone predicament. In the case of an asteroid impact we will be left crippled and incapacitated. Depending on its speed, an asteroid with a mere diameter of 100 meters is regarded as highly destructive and moreover, a 10 km asteroid is widely viewed as an extinction-level event.

      

In addition to the initial destruction prompted by the impact of a considerably large asteroid and the titanic kinetic energy it will convey, it stands to reason that a sufficiently large enough asteroid could cause massive tsunamis, or, should it strike land an impact winter (by displacing large quantities of dust and particles into the stratosphere). The tsunamis will inundate large portions of coastal regions, wreaking havoc and killing thousands. An impact winter is a period of prolonged cold weather due to the impact of a large asteroid. If an asteroid were to strike land or a shallow body of water, it would eject an enormous amount of dust, ash and other material into the atmosphere, blocking the radiation from the sun. This would cause the global temperature to decrease drastically. It is hypothesized that an impact winter could lead to mass extinction. Given the current, aforementioned predicament of the world, a prospective asteroid collision will bring about absolute devastation and will immensely and possibly irrevocably damage the human civilization; if not wipe out. 

      

As of yet, no viable and substantial measures have been taken to avert such a potential debacle. There are some ongoing asteroid detection projects, namely the Minor Planet Detection Center, which has been cataloging orbiting asteroids since 1947, LINEAR, and more recently NASA’s Near Earth Object program office. Investments in these vital programs paid dividends in 2008, when they were able to successfully identify and subsequently compute the exact crash location of a NEO( near Earth object). However, all of these programs only serve for the purpose of identification and any earth bound asteroid will plummet into the earth, impervious and unhindered.

      

Multiple hypothetical Collision Avoidance Strategies have been contrived that can theoretically mitigate or eliminate a pending asteroid collision threat. Based on their procedure, strategies can be classified into two basic sets: destruction and delay. Needless to say, none of these methods have ventured beyond mere theory and are yet to be put into execution.

      

Direct destruction strategies comprise methods such as nuclear weapons deployment, or kinetic impactors(colliding another massive object with the NEO for the purpose of deflection or destruction), that render the asteroid harmless by fragmenting it and scattering the debris so they either bypass the Earth or burn up in its atmosphere. Direct methods are preferable due their immediate effectively and swiftness. Indirect methods, such as gravity tractors( employing a gravitational pull to deviate an asteroid from its imperiling trajectory), laser cannons, and attaching rockets are more tedious strategies, which, however as opposed to direct methods are far more practical in regard to deflecting rubble piles. Provided that many NEOs are loosely packed clusters of rock, direct methods could adversely result in the inadequate dispersion of the asteroid into large fragments. Given the fact that any fragment over 35 meters across would not burn up in the atmosphere, the prospect of defending the Earth against possibly thousands of such pummeling fragments is profoundly daunting.

      

The delay method utilizes the fact that both the Earth and the impactor are in orbit. Taking into account the Earth’s diameter and velocity in orbit, it is possible to avert an impact by either delaying or advancing the asteroid along its trajectory.

      

In essence, our planet has no defense mechanism against asteroid and meteor impact. Some of the impact avoidance strategies posited are more feasible than other; but nonetheless, are yet to be implemented. As time develops however, the impending threat only grows stronger and it is therefore of paramount that we, as humans act as efficiently and briskly in formulating and implementing a practical and viable defense strategy against these celestial threats.

      

The Earth is our haven in the forbidding abyss of space; the only inhabitable planet known that can harbor sentient life forms such as ours. But in spite of all its grandeur and magnificence, our planet is endangered by throngs of threats. The task of protecting our habitat against the many menaces that imperil it is a burden that we mankind must shoulder. The fact of the matter is that in spite of all its scarcity and unlikeliness, asteroid impact is an imminent and grave menace to our existence. It is axiomatic that a massive asteroid will ultimately approach Earth, and when it does, lack of readiness and vigilance will be tantamount to utter extinction.

 

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