Asteroid Affirmative

Small Asteroids = damage

Elizabeth Svoboda 2003 (Discover, Less Danger From Falling Rocks, October 2003, EBSCO, znf)

HAVE SOME PROMINENT SCIENTISTS INADVERTENTLY BEEN PLAYING Chicken Little? Working from computer models, several researchers warned that asteroid impacts could trigger devastating tsunamis with frightening frequency, at least once every 4,000 years. Never fear: Philip Bland, a planetary scientist at Imperial College London, says his improved calculations show that the actual rate is probably much lower. The previous simulations portrayed incoming asteroids as continuous blobs--picture a ball of glue flattening and spreading as it hits a hard surface. Bland developed a more realistic model that allows asteroids to disintegrate on the way in. "We're looking at the forces acting on stone or iron fragments as an object breaks up upon entering the atmosphere," he says. Fragmentation greatly reduces the odds of a major tsunami. To generate a 16-foot-high tidal wave, an object must be about 720 feet wide when it hits the surface. According to Bland's model, few objects that large survive passage through the atmosphere. Asteroid fragments 15 feet wide, capable of forming 300-foot craters, strike Earth every 200 to 400 years, he finds. Chunks large enough to trigger a significant tsunami fall just once every 170,000 years. Bland does not dismiss the danger of asteroids, however. "Even if an asteroid shatters in the atmosphere, it's a substantial threat to human life" he says. The still-mysterious Tunguska Event, an explosion in Siberia in 1908, was most likely caused by a comet or meteorite. Although the object disintegrated in the air, it still managed to flatten 800 square miles of terrain. And scientists still do not really understand how the atmosphere interacts with really large impactors, which will be the next focus of Bland's research. "That would let us see what kind of effect a big comet, for example, might have" he says. PHOTO (COLOR): The Wolf Creek Crater in Western Australia testifies to the destructive power of asteroids on land.
A small asteroid has the capability of causing mass damage – tsunamis, worldwide winter,

Prado 2002 (Mark, “1.7 Earth Impact by an Asteroid: Prospects and Effects”, Asteroids Near Earth—Materials for Utilization, http://permanent.com/a-impact.htm)

If an asteroid of size 200 meters hit the ocean (which covers 70% of the Earth), the tsunami (i.e., giant wave) it would create would inflict catastrophic destruction of coastal cities and substantial worldwide human casualties along coastlines. If an asteroid of size 1 kilometer hit Earth, it would cause a dust cloud which would block out sunlight for at least a year and lead to a deep worldwide winter, exhausting food supplies. The latter is what caused the dinosaur extinction, as well as other major extinctions of smaller creatures in geologic time scales. The 200 meter asteroid hits, which are far more common than the 1 km+ hits, wouldn't show up much in geologic histories on a global scale.

The committee notes that objects smaller than 140 meters in diameter are also capable of causing significant damage to Earth. The most well-known case from recent history is the 1908 impact of an object at Tunguska in the Siberian wilderness that devastated more than 2,000 square kilometers of forest. Previous estimates of the size of this object were on the order of approximately 70 meters in diameter. Recent research indicates that the object could have been substantially smaller (30 to 50 meters in diameter), with much of the damage it caused due to shock waves from the explosion of the object in Earth’s atmosphere. The committee strongly stresses that this new conclusion is preliminary and must be independently validated. Since smaller objects are more numerous than larger ones, however, this new result, if correct, implies an increase in the frequency of such events to approximately once per 3 centuries.