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Another Asteroid Close Call
james was one of a number of people that submitted the news that
the earth has had another near miss, this time with an asteroid. This particular one is thought to be about 300 meters in length, meaning that if it had struck the earth, it would have destroyed an area of say...South Africa. Not to mention the fall out. But
we don't need
a
better system
for watching the stars. Nope. Obviously not.
Hmm... that old chestnut. Missile defense was supposed to take care of asteroids AND missiles, as mentioned in this and this article. Somewhere along the line, the populist (and governmental - often one and the same, but that's another article) opinion was that the system would point in more than out. That's where the problem lies.
Now big tents on the other hand...
jer
We may be human, but we're still animals
- Steve Vai
Easy. E=mv^2 IIRC. So take the mass of something that size, multiply by the square of the impact velocity, and that's the 'energy' released by the impact.
It's not _quite_ the same as a nuclear explosion, but if you get the energy level high enough, then the effects are similar enough that it doesnt matter.
A kiloton is define as 10^12 calories which is about 4 x 10 ^ 12 joules.
A 1000 tons of rock would have to hit the earth at about 1 kilometer per second to have a similar effect - which is quite a small speed if you are talking about relative speeds in space... (escape velocity is 7km/sec IIRC)
Don't know what the mass of that rock would have been, but a 300 metre sphere of rock is going to be _fairly_ heavy. Take some averages, and count a few fingers, and you start realising that several megatonnes of energy are comparatively easy to come by if you're hit by a big chunk of rock travelling at significant speeds.
(This is, assuming I can count of course.)
Duck is also a verb in English. It means "to lower the head or body quickly." The poster to whom you replied probably should have said "Duck and cover!" as he was most likely making reference to various films shown to children in the 50s to "prepare" them for a nuclear attack.
My only political goal is to see to it that no political party achieves its goals.
Actually, the formula is E = (1/2)*mv^2
Now you have: a 300 m sphere rock at about 3 grams/cm3, which is about 42.000.000 tons. Speeds are in the 10-70 km/sec range, let's take 30km/s, or 30.000 m/s
The total energy is (1/2)* 4,2*10^12 (grams) * 30.000^2 (m/s)
or 1,2* 10^22 joules (!)
if a kiloton is 4*10^12 joules, we have that this asteroid impact has an energy of about 3*10^9 kilotons, or 3 MILLION MEGATONS, all of them released on a single point.
I hope that my calculations are not too way off...
There are many groups out there now watching the skys for us. The largest is a government project called LINEAR based at Lincoln Labs. They find more than half of the new NEO (Near earth orbit) asteroids each year that are found. They have a telescope down in New Mexico and have the largest CCD (2560x1960 res) in the market. From their webpage, you can see they have found at least 727 NEO's. So there are a LOT of asteroids comming near us. But in space, near is still very far away. So unpack those bunkers and return to real life, we're still safe for a while. Also, the rate of finding new NEO's is decreasing, so that means that we've (humans) found most of the asteroids that can endanger us.
Nice theory.
Problem is that all the kinetic energy still ends up in our system. One big piece is bad. Split that one big piece into several smaller pieces, and it's even worse. But take things to an arbitrary limit, where you pulverize the entire asteroid down to dust.
Now all that dust impacts the atmosphere, heats to incandescence, and vaporizes. Do *you* want to be in the hemisphere where *that* happens? Imagine New York City under the glare of 70 trillion E-Z-Bake Ovens.
If the asteroid's big enough to have a significant negative impact on human civilization, breaking it up/pulverizing it will not help us. It must be diverted so that it doesn't intersect Earth at all.
It's Bert, and you find him at:
http://ftp.archive.org/html/list_C-E.html
Scroll down until you find:
Duck and Cover 1951
Producer: Archer Productions, Inc.
Sponsor: U.S. Federal Civil Defense Administration
Famous Civil Defense film for children in which Bert the Turtle shows what to do in case of atomic attack.
Descriptors: Atomic/nuclear: Civil defense; Animation
Run time: 9:15