Asteroid Affirmative



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Small Asteroids = damage



Even small asteroids can cause massive airbursts-data shows these events are likely

IRWIN I. SHAPIRO et al in 10,( Harvard-Smithsonian Center for Astrophysics, Chair FAITH VILAS, MMT Observatory at Mt. Hopkins, Arizona, Vice Chair MICHAEL A’HEARN, University of Maryland, College Park, Vice Chair ANDREW F. CHENG, Johns Hopkins University Applied Physics Laboratory FRANK CULBERTSON, JR., Orbital Sciences Corporation DAVID C. JEWITT, University of California, Los Angeles STEPHEN MACKWELL, Lunar and Planetary Institute H. JAY MELOSH, Purdue University JOSEPH H. ROTHENBERG, Universal Space Network, Committee to Review Near-Earth Object Surveys and Hazard Mitigation Strategies Space Studies Board Aeronautics and Space Engineering Board Division on Engineering and Physical Sciences, THE NATIONAL ACADEMIES PRESS, http://www.fas.harvard.edu/~planets/sstewart/reprints/other/4_NEOReportDefending%20Planet%20Earth%20Prepub%202010.pdf)

Our understanding of the immediate damage produced by land impacts capable of producing craters is reasonably mature because their effects are constrained by nuclear weapon tests as well as craters on planetary surfaces. For airbursts, however, a lot of work is needed to improve our understanding of their consequences. For example, many groups have studied the 1908 Tunguska blast. Using insights from nuclear blast data as well as seismograms and barograph records of the Tunguska event, scientists estimated that the height of the explosion was about 10 km and that the energy yield was 10 to 20 MT (Chyba et al., 1993). According to the new estimate of size distribution made by Harris (2009), the average interval between such events on Earth would be on the order of one every 2,z000 years. Work by Boslough and Crawford (1997; 2008), however, indicates that a much lower yield could produce the same effects. They found that asteroid airbursts do not act like point explosions in the sky (e.g., like a nuclear bomb explosion) but instead are more analogous to explosions along the line of descent. In an airburst, kinetic energy (see Appendix E) is deposited along the entry path, with significant downward momentum transferred to the ground. Accordingly, they suggest that smaller explosions with net yields of 3 to 5 MT may be sufficient to produce Tunguska-like impact events. If true, the average interval between Tunguska-like events using the Harris (2009) size distribution (see Figure 2.4) would be on the order of a few hundred years. These results would increase the calculated hazard from smaller objects, perhaps as small as 30 meters or so. Further research is needed to better characterize this threat


Huge Asteroid on the way



Asteroids are out there and threaten the Earth. The big one is on its way now.

Mone, 2003 (Gregory) (Popular Science, Sep2003, Vol. 263 Issue 3, p72, 8p, 1 Color Photograph,)

ITS NAME IS 1950DA, IT'S THE SIZE OF A SMALL mountain, and it's headed for Earth. According to one grim scenario, 1950DA will hit its target — most likely water, since there is more water than land on our planet — and plunge to the seabed in a fraction of a second. When the asteroid meets the ocean floor, it will explode, excavating a crater 11 miles wide. A column of water and debris will shoot a few miles into the sky — to the height of a low-flying jetliner. Then skyscraper-high walls of water will head for shore, eventually breaking in the shallows and flooding the coast. The rest you know, if you saw the weepy 1998 asteroid movie Deep Impact. Worse things may already have happened: One theory credits an 11-kilometer-wide asteroid with roasting dinosaurs alive 65 million years ago. The enormous impact sent debris flying back into space — some of it halfway to the Moon. When the asteroid bits reentered the atmosphere, the heat that was generated flash-baked plant and animal life. (Had that not happened, mind you, we probably wouldn't be here today.) 1950DA is minuscule by comparison, though even a still smaller asteroid could take out an entire city with a direct hit. And make no mistake, there are plenty of space rocks out there; one missed Earth by only 75,000 miles in June 2002 — and wasn't spotted until after it had whizzed by.
It’s estimated that 400 asteroids that could cause global havoc haven’t been found and that there are over a million others that could create regional destruction.

Popular Science 03 (Gregory Mone, Popular Science, Incoming!, August 6, 2003, http://www.popsci.com/military-aviation-space/article/2003-08/incoming, znf)
ITS NAME IS 1950DA, IT'S THE SIZE OF A SMALL mountain, and it's headed for Earth. According to one grim scenario, 1950DA will hit its target — most likely water, since there is more water than land on our planet — and plunge to the seabed in a fraction of a second. When the asteroid meets the ocean floor, it will explode, excavating a crater 11 miles wide. A column of water and debris will shoot a few miles into the sky — to the height of a low-flying jetliner. Then skyscraper-high walls of water will head for shore, eventually breaking in the shallows and flooding the coast. The rest you know, if you saw the weepy 1998 asteroid movie Deep Impact. Worse things may already have happened: One theory credits an 11-kilometer-wide asteroid with roasting dinosaurs alive 65 million years ago. The enormous impact sent debris flying back into space — some of it halfway to the Moon. When the asteroid bits reentered the atmosphere, the heat that was generated flash-baked plant and animal life. (Had that not happened, mind you, we probably wouldn't be here today.) 1950DA is minuscule by comparison, though even a still smaller asteroid could take out an entire city with a direct hit. And make no mistake, there are plenty of space rocks out there; one missed Earth by only 75,000 miles in June 2002 — and wasn't spotted until after it had whizzed by. Now for the good news. First, 1950DA is 877 years away and a 300-to-1 long shot for actually striking the planet and doing the damage in the scenario above, which is part of a simulation recently created by planetary scientists Steven Ward and Erik Asphaug of the University of California, Santa Cruz. And although there are more 1950DAs out there — maybe bigger, maybe due to arrive much sooner — the search for potential killer asteroids is at least under way, though sorely underfunded. Furthermore, a small band of scientists, many of them fueled more by passion than by actual government grants, is working on novel methods to deal with asteroids before they get too close to be diverted or destroyed. (The time spans involved give a new definition to advance thinking: As the foldout on the previous pages shows, some diversion operations would require centuries to work.) NASA is more than halfway through a search for asteroids and comets that come within striking distance of Earth — called "near Earth objects," or NEOs — and are wider than a kilometer. Experts calculate that the chance of an object that size hitting Earth in the next century is only one in several thousand, but the result would be global havoc. After astronomers spot an asteroid in their telescopes, they use radar tracking to get a more precise picture of where it's headed, how fast it's moving, and whether its orbit around the Sun will intersect with Earth's orbit. Before 1950DA's predicted encounter with Earth in 2880, the asteroid will swing around the Sun almost 400 times, while Earth will complete 876 orbits. Of the 600-plus large NEOs tracked thus far, only 1950DA poses any threat at all. But at this stage of the search, there are an estimated 400 potential global killers left to find, not to mention over a million hard-to-spot smaller asteroids capable of regional destruction. (A rock that exploded over Tunguska, Siberia, in 1908 leveled a thousand square miles of remote forest; it was a mere 60 meters wide.) Making the tallying work more tricky are a few long-period comets, which only swing by every few hundred years and are much more difficult to track. The search is only the beginning, and as Jay Melosh, a planetary scientist at the University of Arizona points out, "The question is, If we find one with our name on it, can we do anything?" NASA's search effort receives a paltry $3 million per year, just a fraction of the $25 million that NASA earmarked last year to fix the doors on the Kennedy Space Center's vehicle-assembly building. "I'd like to see more money spent," says David Morrison of NASA's Ames Research Center. But as yet, there's no official program either to build or to test asteroid-deflection technologies.

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