Weight
I thought that they revised the weight up a tad...between 7 and 10 /thousand/ tonnes (at 17m diameter, that wouldn't be tricky)
Astroboffins have figured out where the Chelaybinsk meteorite came from using the power of maths and videos shot by witnesses in Russia. Jorge Zuluaga and Ignacio Ferrin of the University of Antioquia in Colombia have come up with a preliminary reconstruction of the orbit of the meteor, which smashed into the city in the …
If this had hit a town instead of exploding in the air it would have wiped it out. 500 kilotons is a big bang.
I thought that we had a system for tracking and watching dangerous objects in space. Why didn't that system warn us?
It seems to me that it would be worth taking the cash away from the disproved and discredited Global Warming scam, and spending it on improving our meteorite watching capability.
re: I thought that we had a system for tracking and watching dangerous objects in space. Why didn't that system warn us?
Why not? Probably because their budget isn't big enough. I thought I read that it was $5.4 million, but I'm not 100% sure of that figure. It's certainly only a few million (3--6) spent on the problem. Less than what a typical Hollywood disaster movie costs, anyway.
There's no "group" in the way you're thinking of to have internal activity. The Apollos are just a collective name for asteroids whose paths cross the orbit of the Earth but spend most of their time further from the sun than Earth is. This particular rock may have been orbiting for many millions of years undisturbed and it just so happened that this time round it and the planet were both trying to occupy the same bit of space at the same time.
The other known rock that did a close flyby that day, 2012 DA14, has an orbit that takes a few days longer to go round than the Earth takes in its and makes a close approach every 19 years or so. It was three times the diameter (~45m) so around 9 time the cross sectional area and was only discovered a year ago when it made that orbits closest approach.
As ever, the limits are money and time. It needs big telescopes, you're trying to spot black double decker buses several million miles away, looking in all directions all of the time. Ideally you want them spread around Earths orbit round the sun as well as on the planet itself, and also in Venus' solar orbit so they can look out towards us. Then you need enough computer power to analyse the stream of images from the telescopes and look for anything moving, and correlate between telescopes when they do spot something to determine its exact position and orbit.
Define "dangerous objects".
What they're looking for is things big enough to screw the lot of us over and far enough away that we might be able to do something about it before said overscrewing takes place.
Little rocks like this aren't a big issue survival-of-the-species-wise and by the time they get close enough to be spotted and a reliable track calculated there's bugger all we could do about it anyway.
Nuke, because you mentioned 500 kilotons.
"Little rocks like this aren't a big issue survival-of-the-species-wise and by the time they get close enough to be spotted and a reliable track calculated there's bugger all we could do about it anyway."
I guess that because they are not planet-killers there might be something we could do - evacuate an area, for example, if we had time.
The smaller the object, the more difficult to detect and track. Then you have to get the orbital path. All theoretically workable, IF you are looking at the right place at the right time with the right equipment. You've got a better chance of winning that big Irish Lottery.
For all practical intents with current technology and money resources we can't do much about either of them. The small ones we'll spot to late to be able to evacuate. (And let's face it, we have enough trouble evacuating large cities when we have a week's notice that a hurricane is about to hit land when we've got pretty satellite pictures of it. Can you imagine trying to get people to evacuate a city based on the little white dot a meteor would be?) The large ones we couldn't deflect anyway. (And they'd be little white dots too.)
But that wouldn't work, because you would only know where the rock would hit by running a model, and you know that no model can be 100% accurate and therefore, logically, no model can tell you anything.
Though actually that's what our species usually does - panics about the rare spectacular risk (asteroid, nuclear waste, plane crash) and ignores the less rare less spectacular (global warming, diesel fumes, smoking).
Why didn't the system warn us?
Because their budget is limited, as others have pointed out, and the reason their budget is limited is because of all the whingers and moaners going on about first-world problems and why we aren't spending our money feeding starving African children instead of blowing it on useless and expensive space probes...
is 25 times bigger than Hiroshima, they were fortunate that an air burst dissipates in 360 degrees and that it 'burst' 10 miles away from them. still you can understand the damage! and the 2.8 quake the shockwave caused.
(It's still many hundreds of times smaller than the Tsar Bomba Nuke though)