How Many Tiny Chelyabinsk-Class Asteroids Buzz Earth? 36
astroengine writes "The meteor that exploded over the Urals region of Russia in February was a violent reminder that our planet exists in a cosmic shooting gallery. Now, astronomers are focusing on these mysterious small and possibly dangerous objects in the hope of understanding what they are made of and what kind of threat they pose in the future. However, a recent paper accepted for publication in the Astrophysical Journal has identified a possible 'Achilles Heel' of visible light surveys. Using data from NEOWISE (the near-Earth object-hunting component of NASA's Wide-field Infrared Survey Explorer mission), there appears to be a bias in visible light asteroid surveys against finding small (100 meters) dark space rocks. 'With our previous NEOWISE studies, we found that about a third of NEOs larger than 100 meters are dark. It's possible that a population of smaller dark asteroids exists, but we don't have the right sample to test that theory with what we've done so far (in this research),' NASA JPL scientist and NEOWISE principal investigator Amy Mainzer told Discovery News. 'In my opinion it is probable that a similar fraction of small NEOs are dark, but the visible surveys are biased against finding them. They do find some but not many.' On considering the impact of the small Chelyabinsk object earlier this year, it is perhaps sobering to realize that while around 90 percent of NEOs with diameters larger than 1 kilometer are thought to have been discovered, less than one percent of asteroids the size of the Chelyabinsk meteor (17-20 meters in diameter) have been detected."
Asteroid class (Score:3)
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Re:Asteroid class (Score:4, Funny)
That said, nothing is >1 CN except for CN himself of course
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Chuck Norris > 1 CN only when he wants to be.
Re:Asteroid class (Score:4, Informative)
I understand your complaint, I really do. But if they had said "15-20 meter" asteroid, no one would have any idea the destructive potential the asteroid poses. Since the primary topic of the article is that they want to gauge the danger that similarly sized asteroids pose, it makes sense to talk about asteroids using a known sample as a reference point. What they should have said was "looking for asteroids in the same size range as what caused the Chelyabinsk meteor" but that is several times longer and more awkward.
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But what they did say was:
"less than one percent of asteroids the size of the Chelyabinsk meteor (17-20 meters in diameter) have been detected."
Which wasn't that long and not all that awkward.
It is however, something of an un-provable statement.
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I wonder how accurate our current asteroid population estimates are. When Shoemaker-Levy hit Jupiter astronomers were saying that it was a "once in a century, or maybe even once in a millennium" event. Since then we've seen the impact marks of at least three and maybe four more comparable strikes that we didn't see coming. When the first asteroid striking the moon was caught on film it was also thought to be a rare event, now we find that it's fairly common. It's possible that our current low rate of me
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It's half a football field smaller than a Plavnik class submarine, or 8 car-lengths.
In related news (Score:2)
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The news article said it would be 2.5 megatons of TNT, which I would equate to a 2.5 megaton nuclear bomb (which AFAIK, uses the same explosive yields).
While that would be, well, a disaster if it hit near something occupied, it seems too small to wipe out the earth.
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that was a typo; they were off by an order of magnitude.. try 2500 megatons of TNT; much bigger than any bomb ever conceived.
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Yep, about 43 Tsar Bomba's
https://en.wikipedia.org/wiki/Tsar_Bomba [wikipedia.org]
too many? (Score:4, Interesting)
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Is it really practical to find and track these objects?
If you're applying for a research grant with a modest staff and tidy stipend? Then yes, absolutely!
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Is it really practical to find and track these objects? There may be just too many of them.
Perhaps try looking at things from a different perspective: Is it really practical to keep living on one celestial object? There may be just too many threats to justify putting all your eggs in one basket. Uncoincidentally, more space faring capabilities will expand your threat tracking and deterrance options immensely. There is too many of them, only while there is only one of us...
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Does it matter? (Score:4, Insightful)
The Chelyabinsk asteroid scared a lot of people and injured a few people, but it wasn't nearly as destructive as your average day of Russian traffic.
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The Chelyabinsk asteroid scared a lot of people and injured a few people, but it wasn't nearly as destructive as your average day of Russian traffic.
But if it had exploded (or impacted) over the centre of Moscow, London, Washington...
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If it had come in over a major military base on either side the assumption would have been a nuclear attack, which worries me a lot more.
Invoking Betteridge's Law (Score:2, Funny)
No
Seven (Score:2)
is it seven? I'm going to guess seven.
Use Satellite orbiting other planet (Score:2)
One of the problems seems to be that the asteroid struck in day-time so was obscured by the Sun. The Sun seems to be an obstacle to proper tracking of these 'smaller' asteroids on Earth or using satellites orbiting earth.
I'm not suggesting this will be practical or affordable. Has there been any discussion of using a satellite to orbit the moon? Perhaps a potential use of deep-space probes like Voyager 1 will be to track these asteroids in the future (if V1 hasn't been doing this already).
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No, Voyager doesn't have the resolution. From beyond the orbit of Neptune it took a look back towards the Sun and took a panoramic shot of the Solar System. At that point Earth was barely 1/10 of a pixel in size, a "pale blue dot" as Carl Sagan referred to it. From its current location it couldn't even see a major comet at maximum brightness.
Bam! (Score:2)
Large Synoptic Survey Telescope (Score:2)