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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.
DUCK!
Money for nothing, pix for free
I am sorry to say it but, I beleive that a direct hit it what is needed to force our governments to take action. Hopefully it will be not too big and in an unpopulated area, but statistically we are bound to get wacked at somepoint.
Taco Bell has announced that if an asteroid strikes a platform floating off the coast of South Africa, free chalupas to any living survivors.
Here's a list of PHAs (Potentially Hazardous Asteroids) and a simulation of the orbit of this particular asteriod.
Tired of being "punished" by the Slashdot $rtbl since 2002. I'm now over at http://soylentnews.org/ .
But where do we want it too hit? Redmond is too obvious. Washington DC is out, cause I live near there. Hartsfield Airport maybe? Never changing planes in Atlanta again has its attractions... New Holland, Michigan?
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Damn! There went another asteroid we could have exploited for natural resources, thus making a space-based economy viable. This would contribute to the benefit of mankind by improving the standard of living and also making it more likely we can do something about future potential planet-killers.
..is tell us when we're all going to die.
We only get about a months notice of such close passes anyway and there is no way we're going to be able to get a 'Bruce Willis and mates' crew up into orbit in 30 days. A proper asteroid defence system is likely to be at least a decade away, as it is likely to require a number of hefty nukes to persuade an oncoming 300m+ asteroid that it doesn't have right of way.
Besides, I'd feel distinctly nervous about having a space based system loaded with a several very big nukes right above our heads; just imagine what could happen if a very small object hit the system and destroyed it, knocking the bits back into earths gravity......whilst I know you wouldn't get a nuclear explosion, what chances fallout in a similar manner to a "dirty" sub-nuclear weapon ?
Donte Alistair Anderson Roberts - hi son!
Karma: Chameleon
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.)
I always understood that nuking an asteroid was a little pointless. I mean, instead of one big chunk of rock coming towards you really fast, you instead have several.
:)
Find a tile floor. Drop 500 marbles, all at once. Now try dropping a bowling ball.
Obviously, you're not a golfer.
Nasa knows about 47 1km asteroids in near-earth orbits, any of which could make bickering about the RIAA rather short-lived. Their website claims that the best reason to study NEO's, as we don't have an active defense, is to "allow us to store food and supplies and to evacuate regions near ground zero." This is not the sort of confidence that inspires politicians to open their wallet, nor should it.
India and Pakistan are on the brink of bringing the world into a nuclear holocost. Our supplies of oil are depleting while our energy usage goes up. Ebola has broken out in another african village, and Aids rates worldwide are up to 1 in 100 with some areas reaching 1 in 3. Until such a time as there is something realistic we can do about near earth asteroids, that money is better focused on more pressing forms of armageddon.
This Sig is a mnemonic device designed to allow you to recognize this author in the future.
Being an astronomer I probably shouldn't say this, because a pile of cash would rain down on me if somebody decided we needed to monitor the skies 24/7, but what the heck:
The risk isn't that high. Really.
We should rather spend our time ending wars. You may say, we can never end wars. Actually, all the nobel peace prize winners I've talked to think we can, so! ;-)
But on the other hand, I'd really like to monitor the skies 24/7, but such a system should not be designed with one application in mind, it should be designed with the goal of enabling all kinds of projects. For example, I'd like to see a global, dense network of Liquid Mirror Telescopes. That could be used to look for NEOs too.
Employee of Inrupt, Project Release Manager and Community Manager for Solid
Any meteor, asteroid or comet that sets its cold, icy eyes on our beloved Earth needs to be pimpsmacked by one of these.
Russia's 100-Megaton nukes; the most powerful ever built.
One was detonated half-yield at Novaya Zemlya on October 30th 1961.
It was hypothesized that if one placed enough of these nukes in one spot, and detonated them simultaneously, one could knock the Earth of its axis.
It should make short work of a measely asteroid.
Knunov
Why do users with IDs under 100,000 or over 700,000 usually have the most worthwhile comments?
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...
isaac asimov wrote a neat book called a choice of catastrophes he addresses being hit by an asteroid while it is statistically possible it is highly unlikely.
Remember, Asimov was writing (in 1980) before Gene Shoemaker's work from the 60s and after became fully accepted. It really wasn't until all the work identifying impact craters on the earth that was inspired at least in part by Shoemaker's work, and by the Alvarez hypothesis on the K-T extinction (i.e., the asteroid that killed the dinosaurs), got underway that astronomers and geologists took the idea of large impacts seriously (most scientists thought that Meteor Crater was an extinct caldera before Shoemaker, despite the name). Also, Sagan et al.'s work on sandstorms in the Martian atmosphere in the 1970s, which helped to provide a possible mechanism for global effects from local impacts, wouldn't have been completely digested by the time Asimov was writing. Though Asimov was right that overpopulation is the most serious of the issues he deals with in the book (and of course few countries outside Asia take the problem seriously), it would be foolish to dismiss the threat of an impact.
Now, see that raises an interesting point.
Anarchy scares the controlling players of any political power structure, so who's to say that those in charge would share sky-watch information with the populace if they had it?
NASA, back during the Reagan years, had this really low profile military mirror version of itself; A whole second program complete with it's own shuttles which made space runs to plant military satellites in orbit. There's a lot of very expensive & very powerful junk up there which uses classified technologies far in advance of what John Q. Private Sector is allowed to sell in his hard drives. I'd be pretty surprised if there wasn't already enough hardware up there to do decent asteroid surveillance. --In fact, while it might seem like a long shot, I don't think it's that long a shot. . . I'd be willing to gamble that the American government knows a whole lot more about what's going on in Earth's vicinity than they talk about.
Of course, the way things seem to be run on this planet, I'd also be willing to gamble that even with the right hardware and regular reports, wishful thinking is far more pleasing to the mind, and far more distracting. Probably something along the lines of; "Yech! I don't want to worry about this asteroid stuff. I'm sure I'll be okay. I just need to make a pile of luxury resources for my wife and kids before the planet becomes a toxic waste land. This asteroid stuff only happens to poor people. Or at least, I'm sure it's possible to arrange it so it works out that way. .
-Fantastic Lad
Reminds me of George Carlin:
Near miss? It's not a near miss - it's a near HIT!
If it had hit the earth, it would have nearly missed...
Any technology distinguishable from magic, is insufficiently advanced.
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.
You need to define "large" and "barely missing", to even understand what those assumptions are saying.
First, we're doing pretty well at tracking the really large earth-grazing asteroids now - for rocks at least a kilometer in diameter (picture the "little guy" that hit at the end of Deep Impact) we're tracking an estimated ~90% instead of 10% of them now, and the big improvement has come in the last five years or so.
For the stuff smaller than a kilometer (which don't threaten civilization, but can still be large enough to make much of New York City a memory), I don't know that we're doing much tracking at all. So what's your definition of "large"? Thanks to the heavy ocean cover and relatively sparse city covering of the land, odds are we'll get hit in a nice relatively non-fatal location before a city-buster earns its name. And we'll get hundreds or thousands of near misses before then. What's your definition of "barely missing"? I've heard it to refer to anything passing inside the moon's orbit, which is a target with 3,600 times the cross section of Earth. That's a near miss on a cosmic scale, not on a human one.
It's hard to set odds on something like this, but the most informed I've seen would give us about even odds of having a populated area smashed up (damage as much as a trillion dollars) sometime in the next millenium. Not such bad odds that we want to start putting up an "asteroid defense shield", but bad enough that some other valuable activities (pointing more telescopes at the sky, cataloguing asteroids, improving launch vehicle technology) become more valuable for this secondary reason.
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.
But it's sort of in the nature of these things that "near misses" will be very common compared to actual hits. Let's look at the numbers:
If we divide these numbers, we find that an object will be this close to earth on the average something a bit more than 2 million times as often as it actually hits the earth.
So, if an asteroid this size hits earth on the average once every 500000 years, then we should expect that one comes this close to earth on the average 4 times a year.
Offcourse I'm simplifying a lot here, and offcourse this is statistics, we migth just as well be hit one month from now. All I'm saying is that it's not very surprising that something comes "this close" fairly often.
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
If a 100 metre asteroid were to crash into earth, and hit a country with nuclear capability, it would appear at first to be a high yield nuclear attack. Minutes/hours later, it would easily be confirmed for what it really is, but during those crucial seconds where the country in question thinks they're under nuclear attack, might panic and respond by launching their own attack, especially if they're currently having hostilities with another country at the time.
Now, once they launch an attack, what will the rest of the nations of the world do? By the time everyone figures out exactly what happened, half a dozen nations might be actively involved in a nuclear war. Of course, this seems a bit paranoid, but this is the world we live in.
Its very possible that a 100 meter asteroid could sneak up on us and hit with little or no warning. At least if we have a few days warning, we can evacuate ground zero and all affected nations will know what is REALLY happening and won't panic and create more problems in the process.
Should we invest trillions of $$$ in defensive measures against this type of threat? Not now. We aren't even sure exactly what the threat would be. A rocky asteroid would present a different threat, and therefore a different solution compared to one comprised primarily of metal. We would require a different approach to deflecting them. And if we only discover them a month before impact, there is nothing we could do anyways, unless its a VERY small asteroid, and even then, the most we could probably do is adjust the location of ground zero, and not miss the earth entirely. Any solution will require the cumulative effects of time to work properly.
-Restil
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