Earth Impacts as a Threat to Civilization

Earth Impacts as a Threat to Civilization. University of Minnesota. Natalya S. Myers September 24,2002 In recent years we get more amp more facts showing that the present appearance of our planet was formed notonly by slow evolutionary processes, like wind erosion, but also by giganticnatural cataclysms.Geologists findevidence in sedimentary rock that extremely powerful impacts repeatedlyoccurred in the geological history of the Earth.Since the late Paleozoic period i.e. for the last250 million years there are noticeable gaps in the evolution of livingorganisms.

Paleontologists established that around 247, 220 and 65 millionyears ago about 95 of all life on Earth perished. Most recently, for example,the gigantic dinosaurs died out. It is obvious that such extinctions ofterrestrial living organisms are the complex result of many processes.Sharp climate variations, ice formations,fluctuation of the level of oceans, decreases of concentration of oxygen in thewaters of seas and oceans, and different extraterrestrial circumstances all playeda part. However, to name the most important reason, was extremely difficult todiscover.Scientists assumed that at that time theEarth underwent bombardment by large asteroids.

Space and aerial photography,executed in slanting solar illumination, revealed likely asteroid impact sites.Studies at the sites confirmed the Earth s encounters with celestial bodies. Impact with an asteroid about 10 kilometers indiameter is thought to have caused mass death of dinosaurs.

If the impact had arrived on the land, itwould have sharply cooled, but if over the surface of ocean or sea, then watervapor would have produced a greenhouse effect and begun to warm the Eartheverywhere. The Earth may also have witnessed hot nitric acid rains, whoseaction on the environment and the animal kingdom was catastrophic. Such a largeimpact could occur on Earth every hundred million years.Impacts of a smallersize are more frequent and also less damaging.

It ispossible to detect dangerous objects decades before their collision with Earth.Scientists use telescopes to calculate the speed amp orbit of an asteroid.The best way to change the trajectory of motion is to send a rocket towards theasteroid. The purpose of the rocket is not to collide with the asteroid, toexplode close enough to the asteroid to change its orbit.Smaller asteroids canalso be cut by lasers, with no effect on Earth.The technology of the 21st Century should be able to detect all large asteroids amp possible impacts with Earth. We will only have to worry about objectswhose trajectory is very hard toobserve.

To solve this problem, scientists need to see Tunguska-sized asteroidsfrom two points at the same time. The future project of 3 telescopes aroundEarth s orbit can make it possible. We don t know how much it will cost, but incomparison with US Government Military Budget, it is very cheap.The Australian Spaceguard Survey estimatesthe project to cost 10 million US dollars per year. The US Government currently spends around 330billion, according to www.whitehouse.gov, on military projects per year. The impact preventionprojects have the same aim as military projects to protect.

An impact with big asteroid coulddo much more damage than our strongest military enemy, so we should be able tospend at least 10 million dollars per year to prevent another catastrophe.Ialso think all countries in the world should be interested in supportingSpaceguard program.

It needs to be aninternational collaboration. According to Space Daily, funds for this programare reasonable, at approximately a halfa penny US per person, per year in the whole world. Worldwide Spaceguardprogram does very important mission forthe whole civilization.References Australian Spaceguard Survey. 22 September2002.NASA s Near Earth Object Program. 22September 2002.Department of Defense. 22 September 2002.Space Daily. 23 September 2002.