Asteroids Aff



Download 420.22 Kb.
Page13/36
Date07.08.2017
Size420.22 Kb.
1   ...   9   10   11   12   13   14   15   16   ...   36

RISK HIGH



Probability of a collision is high even in the short term

Ames Research Center 2003 - NASA’s Ames Research Center is a world-class research facility located in the heart of Silicon Valley. The center is involved with many high-tech projects, ranging from developing small spacecraft to managing some of the world’s largest supercomputers, and conducting astrobiology research (July 8, * Dr. Harrison H. Schmitt * Dr. Carolyn S. Shoemaker * David H. Levy * Dr. John Lewis * Dr. Neil D. Tyson * Dr. Freeman Dyson * Dr. Richard P. Hallion * Dr. Thomas D. Jones * Bruce Joel Rubin * Dr. Lucy Ann McFadden * Erik C. Jones * Marc Schlather * William E. Burrows, “ NASA NEO News: Open Letter to Congress on Near Earth Objects ” http://www.spaceref.com/news/viewsr.html?pid=9866 )

The latest NEO close approaches are typical of the two dozen such encounters known to have occurred in the 20th Century. These are only a small fraction of the actual number that have occurred; most have gone completely undetected. Such approaches are commonplace in our part of the solar system. The late planetary geologist Eugene Shoemaker put it succinctly: Earth exists in an asteroid swarm. We know that since 1937, at least 22 asteroids have approached Earth more closely than did 2001 YB5, which missed by just twice the distance to the Moon. Five of those objects were larger than 100 yards in diameter. According to NASA, there may be as many as 100,000 NEOs with diameters of 100 yards or larger. Of those asteroids larger than 150 yards in diameter, about 250 are today estimated to be potentially hazardous. The United States has very limited capability to detect these smaller NEOs, which can nevertheless inflict substantial damage upon striking Earth. There is a significant probability (20%) of such an object colliding with the Earth during the next century. Although the annual probability of a large NEO impact on Earth is relatively small, the results of such a collision would be catastrophic. The physics of Earth's surface and atmosphere impose natural upper limits on the destructive capacity of natural disasters, such as earthquakes, landslides, and storms. By contrast, the energy released by an NEO impact is limited only by the object's mass and velocity. Given our understanding of the devastating consequences to our planet and its people from such an event, (as well as the smaller-scale but still-damaging effects from smaller NEO impacts), our nation should act comprehensively and aggressively to address this threat. America's efforts to predict, and then to avoid or mitigate such a threat, should be at least commensurate with our national efforts to deal with more familiar terrestrial hazards. If space research has taught us anything, it is the certainty that an asteroid or comet will hit Earth again. Impacts are common events in Earth's history: scientists have found more than 150 large impact craters on our planet's surface. Were it not for Earth's oceans and geological forces such as erosion and plate tectonics, the planet's impact scars would be as plain as those visible on the Moon.

STRIKE INEVITABLE



Asteroid strike is inevitable- its just a question of whether or not we are prepared

Cox and Chestek ’96 (Donald W., Doctor in Education and James H., Professional Engineer, “Doomsday Asteroid: can we survive?”, Print)//DT

We live in a cosmic shooting gallery. Somewhere out in the netherworld of deep space, hurling toward Earth, is a doomsday rock. The question now is not just detecting it, but what can be done to possibly nudge it off course by one means or another before it strikes the Earth and annihilates a large part—if not all—of humanity. Such a doomsday asteroid could severely disrupt life on Earth, not only for humanity, but for the other species of plants, fish, birds, and ani­mals. Although no astronomer has yet located the killer object (which will be a mile wide or larger) headed for us, it is inevitable, according to most astronomers, that one will eventually appear. Large Earth-crossing aster­oids slam into our home planet every 300,000 to a million years, which means that there is approximately one chance in 6,000 to 20,000 of a cataclysmic impact during the next half century. In other words the Earth has a much better chance of being struck by a large asteroid than most of us have of winning big in the lottery (the chances in the latter case arc usually one in millions). Dr. Tom Gehrcls, a professor of lunar and planetary science at the University of Arizona who heads a team of astronomers that search the sky for such killer asteroids, says. "Eventually it will hit and be cata­strophic. The largest near-Earth one we know of is 10 kilometers in diam­eter (or about 6.2 miles) wide. If such a thing like that hit, the explosion would be a billion times bigger than Hiroshima. That's a 'whopper!' ": This new field of research in the heavens, once pooh-poohed by its detractors as laughingly paranoid, has grown in size and respectability dur­ing the decade of the 1980s. In 1989, an asteroid, a mere half-mile wide, crossed the Earth's path, coming within an uncomfortably close distance. "The Earth had been at that point (in space) only six hours earlier," a House Committee report noted. "Had it struck the Earth it would have caused a disaster unprecedented in human history. The energy released would have been equivalent to more than 1,000 one-megaton bombs."1
Asteroid strike is a statistical certainty

Cox and Chestek ’96 (Donald W., Doctor in Education and James H., Professional Engineer, “Doomsday Asteroid: can we survive?”, Print)//DT

The current guru of the asteroid-watching field is Dr. Eugene Shoe­maker, a sixty-four-year-old, retired, geologist-turned-astronomer with die U.S. Geological Survey in Flagstaff, Arizona. In the 1950s he care­fully studied a three-quarters-of-a-mile crater in northern Arizona which many geologists had previously believed was volcanic in origin. Shoe­maker proved that the hole was created by a 150-yard-widc asteroid that slammed into the Earth 50,000 years ago. The following photograph depicts the immensity of the crater, which is approximately one kilome­ter across and over two hundred meters deep. Using a telescope atop Mt. Palomar, near Pasadena, California, Shoemaker has headed three U.S. teams which hunt for Earth-crossing asteroids. "They're little things and very difficult to spot," he said. "You don't see them unless you use a very large telescope, or unless they come very close to Earth. They're sort of at the threshold of detection."" Congress ordered these NASA studies because the "collection of a lengthening list of Earth-crossing asteroids in recent years... has re­sulted in the accumulation of hard data," according to Dr. Clark Chap­man, an astronomer at the Planetary Science Institute in Tucson, Arizona, a private nonprofit group. "The Earth is bound to be hit. Statistically, it's certain. It's unlikely that a really large asteroid will hit in our lifetime, but it's not beyond the pale."10





Download 420.22 Kb.

Share with your friends:
1   ...   9   10   11   12   13   14   15   16   ...   36




The database is protected by copyright ©ininet.org 2020
send message

    Main page