USC
About this Article
Written by: Joshua Durica
Written on: April 30th, 2013
Tags: aerospace engineering, space
Thumbnail by: State Farm/Wikimedia Commons
About the Author
Josh Durica is a senior in computer science at USC. He is looking forward to starting his masters in game development next fall, also at USC. He enjoys space, games, and games about space.
Stay Connected

Volume XV Issue I > Asteroid Deflection
The threat of an Earth-asteroid collision is very real. Historically, asteroids and comets have proven to be sources of incredible destruction, and they are thought to have caused at least one mass extinction. This has motivated geologists, scientists and engineers to start devising plans to deflect potentially lethal asteroids and protect the earth from the resulting devastating impact.

Introduction

Space is not empty. Out there, above our heads, countless celestial bodies trace their silent trajectories across the universe. Most of these paths diverge from that of the Earth's by unimaginable distances. However, a select few are on course to end their journey by colliding with our relatively larger planet with enough force to cause mass extinction. Until very recently, living things on Earth could only count on the sheer probability of avoiding these potentially dangerous impacts. But now, with the dawn of the space age, scientists are now looking towards the skies and planning on ways to take chance out of the equation by deflecting collision course asteroids using engineering.

Near Earth Object Program

In 1998, the Near Earth Object Program was launched with the goal of cataloging 90% all near-Earth objects (NEO) that measure over 1 km in diameter [1]. As of now, the program has tracked a cumulative total of 10,555 near-Earth objects travelling through our solar system [2]. Each of these bodies is assigned a rating on the Torino scale, which measures the likelihood of collision with Earth. The Torino scale is simply an 11 point scale, where 0 means virtual certainty of no collision, and 10 means virtual certainty of a destructive impact [3].
But why catalog these near earth objects? The answer to that question is that human survival depends on it. As dramatic as that may sound, the threat and dire consequences of an asteroid collision are very real. Massive objects colliding at very high velocities produce destructive results (Fig. 1).
Don Davis/NASA
Figure 1: The potential impact caused by a large asteroid/NEO on Earth.

Impacts throughout history

On the morning of June 30, 1908, a tremendous explosion rocked the remote Siberian tundra, leaving 800 square miles and 80 million trees levelled in a radial pattern [4, Fig. 1]. Known as the Tunguska event, this destruction was far beyond the level of any weaponry that had even be dreamed up at the time. Scientists would later conclude that the culprit was an asteroid 120 feet in diameter, hitting with the force of 185 Hiroshima bombs [4]. This makes the Tunguska the largest impact in recorded history. Fortunately, ground zero was deep in the Russian backcountry, as the resulting explosion would have been enough to obliterate any major metropolitan area. As destructive as Tunguska was, it pales in comparison to what larger asteroids are capable of.
Scientists are currently studying the Chicxulub crater underneath the Yucat√°n peninsula for clues about the extinction of the dinosaurs. Sixty-five million years ago, an enormous asteroid or comet collided with the Earth, exploding with a force of 100 million megatons, and digging out a crater 125 miles in diameter [5]. For reference, the Chicxulub asteroid was 2 million times more powerful than the Tsar Bomba, the largest nuclear weapon ever detonated [6]. This cataclysmic event generated acid rain, giant tsunamis, fires, and threw enough debris into the atmosphere to block out the sun, creating a long-lasting artificial winter [5]. The Chicxulub is theorized to have been the catalyst for the dinosaur extinction, and responsible for the extinction of 80% of sea life, effectively slamming the door shut on the Cretaceous period [5].