[FPSPACE] Fwd: [New post] Redirect: Chicken Little Was Right

David Portree dsfportree at hotmail.com
Fri Mar 8 21:03:20 EST 2013


We *are* taking prudent measures to deal with this "threat." What we aren't doing is providing decision-makers and the public with credible information on the nature and magnitude of the "threat."  Contrary to popular belief (and the dire pronouncements of science pundits eager for attention), not every asteroid causes a mass extinction (in fact, many large impacts have left no trace in the fossil record), the provocatively named Apophis hasn't been considered a threat for several years (yet it's still a favorite bogey, uh, rock), and in all human history no more than 30 people have died from asteroid impacts. Thirty is at the high end of the estimate - ~10 is more likely. I like to tell people about the Chesapeake impact, which occurred about 35 million years ago. It was the largest, most violent impact event since the K-T impact 66 million years ago. It left a crater perhaps 100 miles across (the crater size is not firmly established, but it seems to get bigger with each estimate, not smaller). And, it caused no mass extinction. Even its local effects seem muted, perhaps because it splashed down offshore in deep water. Its crater, much of which is now buried under land, wasn't even discovered until the 1990s.  If we want to save lives, we should make roads safer - ~50K people die on U.S. roads alone every year, year after year, and we just accept it. Or outlaw bananas - I'm sure they've killed far more people than asteroids. Or maybe restrict access to guns. . . All around the world people are studying and discovering asteroids. We've explored more than a dozen close-up, orbited two, landed on one (unless you count Hayabusa, then it's two), and directly sampled one. We've indirectly sampled hundreds or thousands of asteroids by studying meteorites.  We've found all the near-Earth rocks big enough to cause a mass extinction. We've probably found 90% of the rocks capable of reaching the ground and causing devastation. We probably won't find all the Chelyabinsk-class rocks for a long time yet, even if we expand our search programs. The good news there is, they are about as devastating as a middling-sized earthquake or a weak hurricane. We deal regularly with those kinds of natural disasters (and worse). We should send more robotic spacecraft to asteroids to characterize the Near-Earth Asteroid population. Good news is, doing that is cheap, especially if we more fully exploit the potential for visiting multiple asteroids using single spacecraft. Exploration missions to the Main Belt and other populations are costlier propositions, but presumably the NEA population is a random sample of those populations I worry that crying wolf too often will cause people to turn their backs on asteroids. That would be unfortunate, because they are fascinating objects that should be more fully explored.
David S. F. Portree

dsfportree at hotmail.com
dportree at usgs.gov
 
http://www.wired.com/wiredscience/beyondapollo/ 
 
http://astrogeology.usgs.gov/people/david-portree
 


 From: ljk4 at msn.com
To: fpspace at friends-partners.org
Date: Fri, 8 Mar 2013 16:42:00 +0000
Subject: [FPSPACE] Fwd: [New post] Redirect: Chicken Little Was Right





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From: Roger Launius's Blog 

Sent: 3/8/2013 11:39:51 AM 

To: ljk4 at msn.com 

Subject: [New post] Redirect: Chicken Little Was Right 


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launiusr posted: "[caption id="attachment_5009" align="aligncenter" width="640"] Powerful meteorite explosion in the sky over Chelyabinsk, Russia, February 15, 2013.[/caption] I published on March 4, 2013, a new commentary
 on the policy issues surrounding what to do abo" 







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Redirect: Chicken Little Was Right
by 
launiusr 









Powerful meteorite explosion in the sky over Chelyabinsk, Russia, February 15, 2013.


I published on March 4, 2013, a new commentary on the policy issues surrounding what to do about asteroid/meteor/comet impacts.

Chicken Little Was Rightᅵ just appeared on the National Air and Space Museum's blog. It notes that yes, indeed, the sky is falling. Cetainly the impact that took place in mid-February at Chelyabinsk, Russia, provides an important object lesson. We must
 undertake prudent actions to mitigate the threat.



launiusr | March 8, 2013 at 11:39 am | Tags:

asteroid, 
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comet, 
Department of Defense, 
History, 
meteor |, 
Moon, 
NASA, 
politics, 
public perceptions, 
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U.S. Civil Space | Categories: 
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