Rare Event: Meteorites injure people and property in Russia

[kochu]

While everyone was busy looking the Astreoid, this one sneaked through.
Kochu

[starfinder]

I find these facts (below) quite surprising. I think the public may be getting the wrong impression from the periodic announcements by NASA that such-and-such an asteroid has next to no chance of hitting Earth 30+ yrs from now. It seems that most of the dangerous ones have not been found or simply can't be detected. So a surprise impact could happen at any time anywhere.


' "More than 90 percent of rock bodies smaller than 150 meters in size have yet to be noticed," said Noritsugu Takahashi, board chairman of the Japan Spaceguard Association, referring to the asteroids that might approach Earth within the next few years.
...
The U.S. National Aeronautics and Space Administration (NASA) on Feb. 15 estimated the Chelyabinsk meteorite measured 17 meters in diameter and weighed 10,000 tons before it entered Earth's atmosphere.
...
It is nearly impossible to detect small rock bodies of 40 meters or less as they approach," said Shin-ichiro Okumura, another member of staff at the Bisei Spaceguard Center.
...
Among the largest events on record is the 1908 explosion of a comet-like object measuring 100 meters across above Tunguska in Siberia. The blast leveled trees in the surrounding forest for an area of about 2,000 square kilometers.'

Source:
http://ajw.asahi.com/article/behind_new ... 1302160058

[superiorstream]

Hi,All
Actually I see this meteor as a wake up call to the following facts--
1)The use of more and more glass as a building material.Glass cant stand much stress and vibration/shock wave.As you can see from those report,most of the injured are from broken glass which turned into knifes and weapons when fractured.Just imagine,if that object had 'exploded'--actually not exploded,but attained mach1 and above,creating the sonic boom and shock wave--
above Singapore;with all those 'modern' /newly build building with All those glass panel /walls outside etc;and those fractured glass raining on the people below them;what will be the amount of injured/or even killed?
2)Today people ALWAYS talk of money and growth and return.Thus we heard of people giving a valuation to asteroid to be worth billions of dollars;estimating its mineral value etc. and suggest doing asteroid mining in fulture.Such people should be sent to a --no monatory return, physics class and force to study physics ;espec. on gravity and planetary orbit.Do you know that such mining of
asteroid can actually CHANGE the orbit of the asteroid.We see miner on earth refusing to bring the ground to its original state on earth and so dont expect them to RESTORE A MINED ASTEROID TO ITS ORIGINAL ORBIT.The possibility of AN mined asteroid suffered a changed orbit--due to changed mass
and propulsion of exiting mining craft say---and proceeding to collide with the earth wiping out a whole city is a possible ECONOMIC cost of such space mining.How about that view of GROWTH,MONEY and RETURN.?Probability is low?;so does this one and this small one ALONE cause more than 1200 injured!!

[starfinder]

BBC News - Meteorite fragments found in Russia's Urals region
http://www.bbc.co.uk/news/world-europe-21494963

"We have just completed the study, we confirm that the particulate matters, found by our expedition in the area of Lake Chebarkul indeed have meteorite nature,"

"This meteorite is an ordinary chondrite, it is a stony meteorite which contains some 10% of iron. It is most likely to be named Chebarkul meteorite,"

[starfinder]

Regarding potentially hazardous asteroids, based on this article (and paraphrasing from it):
http://www.space.com/19837-russia-fireb ... prise.html

it seems that there are 3 size categories of asteroids / meteoroids, and about which the state of present knowledge is as follows:

(1) The meteroid that exploded over Russia last Friday was about 15 meters wide. (Elsewhere stated to have had an explosive force 30 times that of the Hiroshima bomb, but thankfully it exploded at a very high altitude, or else.....)

Asteroids of this size are difficult to detect and very numerous, so it will take a long time for astronomers to find and map out their orbits. Researchers have spotted less than 1% of asteroids at least 40m wide.

Space rocks of this size can cause severe damage on a local scale, as the 1908 Tunguska Event, when a 130-foot-wide object exploded and flattened 2,100+ sq km of forest. (That's 3 times the size of our sunny isle.)


(2) Observations by NASA's WISE space telescope suggest that about 4,700 asteroids at least 330 feet (100 m) wide come uncomfortably close to Earth at some point in their orbits.

To date, astronomers have detected less than 30% of these, which could destroy an area the size of a state if they slammed into Earth.


(3) The Near Earth Object Program Office at NASA is focusing on the larger asteroids first, which are the ones that are the most hazardous.

NASA has identified 95% of the 980 mountain-size asteroids (at least 1 km wide) thought to be cruising through Earth's neighborhood. None of these are known to pose any threat to Earth.


Overall, scientists think 1 million or more near-Earth asteroids are out there, and just 9,600 have been identified to date.


So... it seems that any city on Earth (such as our Little Red Dot) stands to be obliterated at any time literally out of the blue by asteroids which are totally unknown, i.e. the 99% of asteroids in Cat 1 and the 70% of asteroids in Cat 2. Presumably, the larger Cat 3 asteroids would be detected in advance (save the dinosaurs!) and we can all migrate to the Sahara before then.


Time to get worried?

Or take comfort from the fact that we never bothered about this before until the last several years (ignorance is bliss), and nothing happened anyway.

Nevertheless, it's much food for thought! I didn't know before that so little is known about the Cat 1 and Cat 2 asteroids.

[Hardwarezone]

Half tonne fragment have been recovered from the lake

http://www.bbc.co.uk/news/science-envir ... icRSS20-sa

The fragment was then pulled ashore and placed on top of a scale for weighing, an operation that quickly went wrong.

The rock broke up into at least three large pieces as it was lifted from the ground with the help of levers and ropes.

Then the scale itself broke, the moment it hit the 570kg (1,255lb) mark.