The Earth is under continuous assault by extraterrestrial objects, many of which are too small to pass through the atmosphere. However, those large enough will cause devastating effects and thus it is important to defend against them. The first step for defense is survey and detection for Near-Earth Objects (NEOs), current initiatives such as the Spaceguard Effort and telescopic systems are currently in place, and future detection efforts will enable us to detect smaller NEOS. The mitigation strategies of Kinetic Impactors and Solar Collectors are looked at. The Kinetic Impactor is simple and effective and available with today’s technology while solar collectors although promising, wont be available till the necessary technology is available in the future.
Under continual bombardment by cosmic objects, our Earth is in a dangerous place. Although the vast majority are tiny and burn up in the atmosphere before reaching the ground, larger objects are capable of penetrating the atmosphere with potentially devastating effects. Evidence of collisions is abundant on the crater ridden surfaces of mercury and the moon1, both of which have neither atmosphere to protect against smaller objects nor volcanism to reshape its’ surface.
On earth, the threat and danger of near-Earth objects (NEOs) is real, most notably is the object in 1908 that annihilated 2000 square kilometers of Siberian forest1, 2. The object in question, which the explosive force of 12.5 megatons of TNT was only 60-meters in diameter2. Although considered small in size and presenting threat to a limited area, the explosive force of a similar sized NEO in an urban area would cause hundreds of thousands of deaths. NEOs with diameters, one kilometers or more can possibly cause global devastation and although chance of occurrence is extremely low, the results would be catastrophic1, 2, a classic case of the “zero times infinity” problem1. Figure 1 well illustrates the negative relationship between NEO impact frequency and NEO size.
Consequences of NEO impacts depend on factors such as mass, density, impact angle and relative velocity with respect to the Earth3. Major impacts would have immediate effects such as blast, firestorms, severe acid rain, the creation of pyrotoxins and the eradication of the ozone layer2. Such impacts could also trigger volcanic and seismic activity leading to greater environmental disaster2. Sudden climate change can also occur with a great amount of dust and debris is agitated and thrown into the atmosphere, blocking out the sun3. Major impacts at sea would devastate coastal regions with a massive impact-induced tsunami2,3 . Any one of these events are likely to be considered doomsday scenarios but they can be prevented through the defense against NEOs. Defense of the earth against Near-Earth Objects (NEOs) can be achieved through survey and detection of NEOs, current mitigation strategies such as kinetic impactors and through...