| Posted on Feb 19, 2013 02:56:13 PM | William Cooke | 30 Comments | |
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This is the question that keeps cropping up, and it deserves an answer. Images are being posted showing the fragments and they look like ordinary chondrites of asteroidal origin. This material is dark, and not very reflective, which makes it difficult to spot out in outer space, especially if the object is bus or house size.
Astronomers measure brightnesses in magnitudes -- the larger, more positive the number, the fainter the object is. The Sun is magnitude -27, the planet Venus -4, the star Vega 0, and the faintest star you can see is about +6. The best asteroid survey telescopes have a magnitude limit of about +24, which is about 16 million times fainter than what you can see with the unaided eye.
We can now use the latest orbit determined by Dave Clark (and yes, the meteor came roughly from the East, not from the North as stated in the initial NASA reports) and combine it with the estimated size and reflectivity to figure out when we should have seen the meteoroid in the asteroid survey telescopes. The calculations can be displayed in a graph like this one. Note that, even with very large telescopes, the meteoroid would not have been visible until a mere 2 hours (135,000 km from Earth) before impact -- very little time to sound a warning.
Even if we had been looking at the right spot and the right time, there is another problem -- the meteoroid would be in the daylit sky, and telescopes cannot see faint objects in the daytime.
Simply put, the meteoroid was too small for the survey telescopes and came at us out of the Sun.
Tags : DA14, Marshall Space Flight Center Meteoroid Environment Office, NASA, Russian meteor
Don't kid yourselves!!! Nasa sees everything that goes on up there they see everything they seen the meteorite that hit Russia
Why our satellites did not detect,the sun did not blind them.
It`s a bit scary, if a meteor cant be tracked by radar/satelites etc, what`s stopping some rogue nation firing off a few nuclear bombs undetected
I think they new it was going to hit but they kept it quiet could you imagine how everyone would react if we were told earth was going to get hit by an asteroid there would be mayhem everywhere
This is quite an interesting post, but not surprising. For those saying we should develop satellites with radar or to destroy asteroids, there are problems. Firstly, there is a lot of radiation out in space that could disrupt this detection (not to mention finding an orbit with all the satellites and junk up there already). Secondly, in order to effectively remove the threat of an asteroid collision, it would need to be vaporized, which takes a whole lot of energy. Simply splitting/fragmenting it could cause more pieces to hit earth (which may or may not be better than a near miss or full impact).
Also, if the meteorite had come in vertically, it could have been vaporized as it would have experienced the full frontal effect of the atmosphere rather than cutting through at an angle.
If we are unable to detect small or faint meteorites it means we are in great danger,so we need a new way to detect and monitor the life of meteorite right,we should start a new project in finding a neway to monitor them. If we look close back to the meteorites that took place and our mistakes conclusion we can fix this by looking for new ways to predict pathways of them can someone please send me data of atleast 5 last meteorites that has triken the earth and the misleading data about them
So there is stealth in space after all.
Very nice graph. I think it also says that if we only have a telescope that can only detect Chelyabinsk-typed objects in its 8 magnitude than we practically have no pre warning time. This graph is specially made for this kind of meteoroid so I think the relation between apparent magnitude and hours before impact is approriate.
I just wander if we would be told if a large a object big enough to wipe out a city was heading for the earth or be kept in the dark, can you imagine the panic all hell would break loose there would be total mayhem if people were told they had x amount of days to live.
After seeing the orbit diagram of 2012 DA14 around the sun, which seems to be rather small, I've been wondering since the meteor passed so close to Earth what kind of "tug" or pull the meteor might have gotten from Earths gravity and if it did get pulled (or pushed?) would this affect it's future trajectory and bring it in closer next time or perhaps farther away or worse yet, whamo!?
I wonder how (un)probable was such a coincidens (two asteroids like those just happen to come close to Earth with just few hours interval and one of them actually hitting not somewhere in the ocean but one of continents? Is it more or less probable than (let us say) a 10 times bigger asteroid coming and hitting?
It is extremely surprising that scientists have not invented a device to look in the sky when the sun is blazing - there must be a way to see better in the light! Why has this never been attempted?
The Rusian meteorite entered Earth low (shallow angle 20 degrees), what if it entered vertically, right above head, 90 degrees angle?
What damage could it have caused? Another Tungunska? Thk, GB
Looking at the orbit diagram of the Russian meteor, it seems the Earth will cross that orbit again in the autumn. Is there a risk to meet any leftovers from the Russian meteor in the autumn of 2013?
Quite a co-incidence it was so close to the Tunguska area.
Given that 3 quarters of earth is open ocean, how many times per year do events close to this size happen un-observed?
I agree with the opinion of Carl Sagan, that any high tech system that could deflect an asteroid of this size AWAY from the earth could also direct a similar size object TOWARDS a target on earth. Robert Heinlein wrote a chilling scenario of this in "The Moon is a Harsh Mistress" decades ago.
In what way has the weight been calculated of this 17 mtr.surprising object.?What was the density?
Cincerely,
Hennie Frans
IMHO, text and diagram are very well explained.
If something, I'd just point out (as someone said previously in this forum) that in the last moment, when the meteoroid was already in the atmosphere, it became suddenly brilliant, almost as the Sun. That could have been considered in the diagram. Just saying.
Give us your 2 hour warning and let us determine what to do.
Start focusing those telescopes and satellites on Earth and stop sending our ultra expensive satellites to explore those areas of our universe that cannot affect our planet.
Let's face it NASA you got caught with your pants down!You didn't even know the direction it came from!
Why cant NASA employ dark lenses of intensity enough to be able to view the day sky ?
I know I'm only 16 but... Whats the real point of knowing these Astroids are going to hit. If you tell the world we are gonna get hit by a Astroid, it will cause world wide panic.
> "... yes, the meteor came roughly from the East, not from the North as stated in the initial NASA reports"
It is still unclear why NASA, in their initial reports, could be so sure the meteorite and the asteroide was unrelated, or how they at the same time could tell us about the orbit of the meteor -- they didn't know the direction. Of course even NASA can make big mistakes, and the NASA scientists are not more than humans, which means there is a lot of prestige even among them.
Well,
The EARTH , our dear home planet was cowardly hit by a companion of the famous DA14- 2012 ASTEROID .
We know that asteroids have satellites mooving around them
So , from now on NASA and all the world community should joint in view of recalculating backward the orbit of all meteorites entering Earth atmosphere.
It would have been a world disaster if this meteor asteroid have fallen on a Russia major town or a nuclear plan!
This is just a warning to us
Hourse before impact/Apparent Meteor Magnitude: 10/16; 5/15; 2/13; 1/11; 0/-28 :)
NASA should now plan to invent an eye in the sky that can see all Near-Earth asteroids in the day time, to forestall future reoccurence of the Russia meteorite impact. I believe NASA and European Space Program can jointly handle this. There is enough budgetary provision that can cover this.
should we be scared? i mean if this asteroids where not detected how safe are we from this happening again? should we be worried? with all the technology that exist! we have curiosity in mars cmon!
Is there any way to work the entry trajectory backwards and determine the object's original orbit? Maybe it will be found in some archived observations, especially if it has crossed Earth's orbit previously.
meteors are like a box of chocolates:/
I am not an astromer, but i do understand the problem you have posed of detecting +24 magnitude objects, and that too in near daylight from earth based telescope.
But is that the only way to detect an approaching asteroid?
If you ask me I would prefer to put few sun synchronous nuclear powered satellites orbiting the sun just like earth, but around few million kms from earth. No problems of daylight vision.
And instead of optical detection I would prefer radar for knowing any object approaching earth. It should give warning at least few days before the actual hit.
Finally similar to these detection satellites, there should be few satellites to intercept and destroy the approaching objects.
No fund problems, all the countries can contribute.
10 nuclear powered long lasting satellites is all we need and offcourse expertise of NASA :)
hello Nasa. you still not corrected your orbit
The diagram must be wrong: As a larger Magnitude means a fainter object, the prewarning time should be shorter, not longer for an increasing magnitude.