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by Launchspace Staff
Bethesda MD (SPX) May 04, 2009
This isn't just "buzz" to get you excited about a new movie coming; we really are being buzzed by asteroids and other NEOs (Near Earth Objects), and one day these conjunctions could become collisions! There are lots of NEOs out there orbiting the sun.
Some, like comets, are less worrisome since they are composed primarily of ice and small, rocky particles that dissipate upon entering Earth's atmosphere. Others, however, like asteroids are thought of as minor planets that are large enough to damage Earth and its environment if an encounter should take place.
Astronomers estimate that there are approximately 1100 near Earth asteroids bigger than one kilometer in diameter and more than one million that are larger than 40 meters in diameter. Those smaller than 40 meters tend to burn up in the atmosphere, but the impact of a 40-meter diameter asteroid is equivalent to a three-megaton bomb! One megaton is the equivalent explosive power of one million tons of TNT.
For comparison, the Little Boy atomic bomb dropped on Hiroshima in 1945, exploded with an energy of about 15 kilotons of TNT.
Larger NEOs of about 2 kilometers in size could impart energies in the category of about a million megatons! Such an impact could result in an "impact winter" with global loss of crops and subsequent starvation and disease.
Large impacts could cause mass extinctions of species. And....scientists know that most of the larger asteroids are as yet undetected! How do we detect, and better yet, deflect such large asteroids?
Eventually, one of these will be spotted. And when that happens, who do we call? Right now there is no one to call, because the world has no defense against pending large asteroid encounters! If this is troubling, here is the bad news.
On March 2 of this year, asteroid 2009 DD45 zipped just 41,000 miles above Earth at a speed of 12 miles per second at its closest point to Earth. Amateur astronomers aided professionals at the International Astronomical Union's Minor Planet Center by providing measurements used in refining calculations of the asteroid's orbit.
But, astronomers did not even detect the asteroid until just a couple of days before it zoomed by Earth; far too late to take any preventative action. This was not an isolated incident as many NEOs come this close to Earth and zip by undetected!
Scientists have demonstrated that several large NEO impacts in the past have altered both life and the environment. While the probability of a life-ending impact is low, scientists know that potentially critical collisions are inevitable. Why are we not doing something to mitigate or hopefully prevent such a catastrophic event?
The answer to this question is complicated. As humans, we focus on potential dangers only when they are imminent, or after the fact.
We react when the danger becomes real and the situation becomes urgent. However, deflecting large asteroids is not easy, simple or inexpensive. We do not yet know how to do it, but we do know it will require early detection and long-term investments on a global scale.
We want to start thinking about ways to protect Earth from NEOs and we need your ideas. Please send them to Launchspace and we will publish the better ideas in future articles.
Asteroid and Comet Mission News, Science and Technology
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