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Nine Hundred Asteroids in Near-Earth Orbits
SEWilco writes: "This Discovery.com item points out a new estimate of 900 asteroids in orbits closer than Mars. Cornell University's William Bottke did a new study of The Spacewatch Project's small-object search. This estimate says that we've found 40% of the nearby asteroids. Well, I'm glad that we've started looking before a disaster, unlike 'Rendezvous With Rama'." Or "Lucifer's Hammer."
Wouldn't we expect that the greater mass of the large planets, and consequently greater gravity, would compress all their matter into denser (solid) forms?
Whilst it's still an open question thanks to the huge pressures inside Jupiter, it is theorised that Jupiter does have a solid core surrounded by a layer of liquid metallic hydrogen - see this page for some more information. Since Jupiter is so large the gravity at its outer edges isn't enough to overcome centripetal forces and cause the entire planet to collapse to a solid core.
And a related question: our solar system has solid and gaseous planets; is there any fundamental eason that there couldn't be liquid planets, or is that just how it happens to fall in this particular uncharted backwater of the unfashionable end of the western spiral arm?
Well, there aren't that many liquid elements at the temperatures present in the Solar System - the material that formed it would have been mainly simple elements that were either gaseous or solid at those kinds of temperatures. IIRC some of the outer moons have liquid ammonia and methane on their surfaces, but in terms of overal quantity these substances remain rare.
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Jon E. Erikson
Jon Erikson, IT guru
But we do know (approx.) how many we have not found! To find out how many fish are in a pond, one starts fishing. As one extracts fish the rate at which one catches fish will drop. One then interpolates the zero-crossing, and the integral is the total number of fish that were there to start with.
Dog is my co-pilot.
Http://szyzyg.arm.ac.uk/~spm/neo_map.html
;-)
Delivering a dose of harsh reality to the world for the last 2 years
The important thing about the asteroid threat is that it's one of the few dangers to the human races that
(a) Can Kill us All
(b) We Understand
(c) We have a remote chance of avoiding using modern technology
But Fundamental to this all is the fact that we need to get as much wartning as possible - that's why we should be spending more money on telescopes and serach programs.
In fact - we're so underfunded that I've been seduced away from my job of 'saving the world' to go and work at myplay.com.....
So you know which Music serivce provider to blame when armageddon comes calling.
Using the latest equipment stationed in orbit around the world, scientists barraged humanity with radio and X-Rays mapping out large infestations of so called "dead" spots. Using Open GL 3D CAD programs, they then mapped out and ruled out areas that were electromagnetically shielded naturally. The results were then run through a beowulf cluster, and parsed against hospital records for incumbent lead poisoning.
(Note: Only those idiots who are dense (aka lead headed) fall under this census. Airheads require space density measurement equipment, scheduled to come online in two years.)
The results of these tests were astounding, to say the least. Of the Billion or so idiots who were cataloged, a random selection was made to track these idiots through interferometry. (Judging by the interference they caused with others, and their discussions) These results were then sided against web hits, and so called "Pirst Fost" or first post messages.
Looking at the data, Cowboy Neil was actually dumbfounded to see that, in a 3 dimensional internet, around 900 of these Idiots could be found orbiting slashdot.org at an extremely high rate of speed. Impact collisions, and therefore the spread of such idiocy was extremely high, due to morons missing the "pull up" signal from more intelligent data packets.
krystal_blade.
It will be easy to motivate our fellow man; there is hardly anything people treasure more than not being annihilated.
Why worry? It's not like there are any dinosaurs around anyway...
And a related question: our solar system has solid and gaseous planets; is there any fundamental eason that there couldn't be liquid planets, or is that just how it happens to fall in this particular uncharted backwater of the unfashionable end of the western spiralx?
Well, there aren't that many karma elements at the temperatures present in the Slashcode System - the material that formed it would have been mainly simple slasjbots that were either gaseous or solid at those kinds of temperatures. IIRC some of the karma whores have liquid ammonia and methane on their surfaces, but in terms of overal quality these substances remain rare.
The article suggests that it is difficult to track the asteriods and see if there is a chance they could hit Earth. Isn't this something that could be done SETI@home style ? I'd much rather be looking for asteriods that could kill millions of people than looking for aliens.
Better call Bruce Willis!
BTW, somebody want to buy a 2 KVA generator? Only 6 months old, hardly used. Comes with 200 gallons of petrol. Can optionally throw in a solar panel and radiation proof undies...
A)bort, R)etry or S)elf-destruct?
More importantly, the asteroids would be more VALUABLE to reach than the moon. Actually the moon is relatively easy to reach, there just isn't much there to make it worth visiting.
The real trick, as outlined in The Case for Mars, is to establish a Mars waypoint. That opens up the entire asteroid belt for mining. Due to unpleasant technical details (see the book, IANAE [engineer]), it's apparently much, much easier and cheaper to mine asteroids from a Mars base than directly from Earth. Apparently even considering the vast mineral resources of the asteroids, once you get it all back to Earth, if you don't have a Mars waypoint you'll have spent more than you could profit.
None of which is particularly relevant to the main topic, of course...
Slashdot quality declines as the number of hot grits posts decreases. - Provolt's Law, Apr-09-2005
Pick some sample regions. You know how many asteroids you know of in those regions. So do a careful search of that section and see what portion of the ones that you turn up are new.
Cheers,
Ben
My usual seat in the cluetrain is at A HREF="http://pub4.ezboard.com/biwethey.ht
If an asteriod big enough to level NYC were to hit Earth, the first we would probably hear of it would be when it hit.
This is almost a certainty if it came from the day-side. (A few years ago a pair of mountains did this and were spotted heading *away* from us - they had actually come closer than the moon.)
And even if we did, how quickly could we put together a mission to divert an asteroid? Even if we did, would it work?
If you try to nudge an asteroid with a nuclear bomb and instead shatter it, what would have possibly wiped out a city could cause significant damage across an entire hemisphere instead.
And don't count on insurance. This would be classified as an "act of God" and insurance companies will not be liable unless you purchased special insurance for it.
Cheers,
Ben
My usual seat in the cluetrain is at A HREF="http://pub4.ezboard.com/biwethey.ht
Nemesis by Bill Napier is a novel on this subject... and it's pretty damn good (Even mentions linux). Bill Napier was talking about killer asteroids a long time before anyone else - you should read his books.
No need to blow the thing up... if you have resolved all the trajectories of earth orbit crossing asteroids, you will know many years in advance if and when it will hit the earth. All you have to do then is speed it up or slow it down a tiny fraction of a %. Over the course of billions of miles left to travel, this adds up to a huge change in the trajectory, at a potentially very low cost...
If the object is small enough, simmply crashing a satelite into it could be enoug.. otherwise landing a probe on it's surface, with a small rocket engine to give it a gentle push could do the trick. Attaching a solar sail onto it was a similar, even cheaper solution proposed somewhere, but I don't remember where I read it.
Ofcourse in the case of a real dinosaur killer, a comet, we are screwed, because by the time you see it, it's going to hit in only a few months. (or a few million years if you can measure it's trajectory accurately enough to know it's not going to hit for another few of it's orbits)
If you are going to go through all that trouble, wouldn't it just be much easier to nuke the city of your choice? It would take years and billions of dollars to send the asteriode to the city. Chances are that once the thing reaches the city the country will no longer be pissed off; or the country in question will figure out a way to stop the asteroid.
It would be MUCH easier just to strap a nuke on the back of some mad man and smuggle him into the country.
You can't rule out the fact that the rulers of the saddestic country are human. I hope morality would oppose them causing distruction on such a scale (I believe this is what kept the cold war cold.) If the morality of the leader isn't enough, I doubt any group of citizenship (not even Iraq) would stand for mass distruction on such a scale. When you talk about killing millions of people the pety arguements of a couple of countries just doesn't seem important anymore.
Well, I'm glad that we've started looking before a disaster, unlike 'Rendezvous With Rama'." Or Lucifer's Hammer.
The people of Earth were actually pretty lucky in those books. Humanity survived in both -- pretty well in Rama, not as well in Hammer. But they survived. It wouldn't take too big an asteroid to kill us all, so don't go kidding yourself that those books describe worst-case scenarios. They don't.
--Jim
The probability that any of these is going to hit a few months after we find it is vanishingly small.
We're all here because the chance of anything large hitting us is so remote that no extinction class impact events have happened in MANY millions of years. We can take our time about finding these, maybe a few centuries before we should really consider ourselves tardy.
As for the prospects of deflecting an orbiting body, it's much more likely that we'll have decades of forewarning rather than months for a regular Earth crossing orbit. That should give us more time to plan and more opportunity to act early. We might not have much warning for a cometary impact but unless it's an old one it should be easy to spot and maybe easier to deflect through heating.
As for other deflection schemes, there seem to be several viable alternatives. The solar sail option sounds promising and NASA is about to test the technology. Using anything up there you can find as drive mass for the nuke also seems like something you would consider. With all those earth crossing bodies it might be possible in a few decates to rendevous with one at closest approach to the threat and mine some mass for use as projectile matter for your nuke. It isn't so far fetched when you consider that NEAR is in orbit around such an asteroid.
Given the likely forewarning (not the Hollywood timescale) a NEAR like scouting missions to the threat and other objects followed by a flotilla of missions intended to deflect the threat seems like the most likely scenario.
I doubt we'll ever see this type of mission for thousands or even millions of years. We should probably be more worried about smaller more frequent climate threatening objects, and we should be able to do more about those although they are harder to spot. I guess they're not as sexy as big Earth busters but they're still extremely threatening and vastly more likely to happen. These might be frequent enough to merit a sense of urgency in searching for them.
At least according to this article on spaceref.com which states that the eartch approaching asteroid 2000 BF19 has a small probability of impacting Earth. And this press release would seem to counteract the claims made here, since NASA states they have cut their estimate of the total number of large asteriods in the Solar System in half.
Perhaps trusting statistical analysis is the problem? Whats the saying "There are lies, damn lies, and statistics"?
"The first time I got drunk, I got married. The second time I bought a chimpanzee, after that I stayed sober" Arian Seid
I believe the problem with long-range asteroid prediction is not computational power. The N-body problem with only a few dozen good-sized gravity wells in the system is easily simulated with a desktop machine. The problem is the accuracy of our measurements. The magnitude of the error term dominates the significant result pretty quickly as you extrapolate measurements centuries into the future.
What are we to make of the lack of public response to the problem of protecting against meteor collisions? With--what?--3 movies two summers ago about major collisions (okay, one was about a comet, which I don't think anyone would survive), still no one has much of a reaction. I don't know whether to revive my faith in humanity, since those execrable had so little effect on the national consciousness, or to leave it dead, because we never wake up and try to save ourselves until it's too late.
See, we should have kept those iridium satellites up as shielding...
Asteroids, specifically ones with metals, water, or volatiles are a prime target for mining. Any serious exploration of the solar system, or attempts at constructing habitation in space will require manufacturing capability in space, which will require loads of raw materials. Near Earth asteroids, such as the ones in the Apollo, Amor, and Aten belts may be easier to reach than the moon.
After all, the film was highly regarded for its scientific accuracy and convincing portrayal of how the US would deal with such a situation.
Krakatoa is a caldera, about every 1000 years is its term. Yellowstone is another caldera due now with the consequences you, everybody with any sense and I fear. The place has risen 8 metres in the last century. Geologically this is scary.
"Common sense is nothing more than a deposit of prejudices laid down in the mind before you reach 18" Einstein
The tracking of space debris is performed by the U.S. Space Command's Space Surveillance Network, not NASA.
I must wonder when a asteroid will first be used in war. With 900 near earth objects, you could decimate the world. the saddest thing, is that the technology is being developed to propel clectial objects with their own content as the fuel. Redirect an asteroid for Washington DC, Chicago, and LA and you could run your ground troops in to sweep up while the chaos ensues. While this may not be as effective in the US, a small nation would easily be taken by this method.
Pax Digitalia
As far as I know, should we be hit by something a few KM across, the devastation would be immense. Even after the initial impact had settled, there are likely to be worldwide temperature falls of a couple of degrees.
I heard of some research done on tree rings that suggests that there was a similar global climatic catastrophe around the middle of the ninth century. This produced frosts in summer in temperate regions for a few years. Lord knows how cold it git in winter. This was caused by Krakatoa, but estimates suggest that an impact by one of these asteroids at about 6KM across would produce similar results. Here is a link to the NASA page covering this topic.
The last major climatic event (being Krakatoa going bang) in the dark ages was probably responsible for the death of King Arthur.
"Common sense is nothing more than a deposit of prejudices laid down in the mind before you reach 18" Einstein
I'm curious though, why should we believe that scientists/astronomers can track _every_ asteroid in a near-earth orbit, when they can't even track _every_ piece of space debris in orbit around earth now?
Objects in Earth orbit that could cause damage to a satellite or space station can be as small as a speck of dust. Asteroids that could cause serious damage in case they hit the earth are dozens of meters or more in size. It's not easy to track them becasuse there is a lot of sky to cover, but it is feasible.
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Stop worrying about the risks of nuclear power and start worrying about the risks of not using nuclear power.
I've read that a 1kilometer asteroid falls on earth every 1e6 years, and that an asteroid of that size would kill 1e9 humans.
So, we can say that the mean is 1000 people/years. This is more than plane crashes (which is about 500 people/year).
But I really wonder; if you don't know how many are out there how can you tell that you cought 40% allready ?
Which begs the question:
What's wrong with many small pieces coming into the atmosphere?
The reason that a big asteroid makes it through the atmosphere is that there's so little surface area. It's like saying that a large block of ice takes 1 day to melt, while a similar block smashed into pieces takes 2 hours. Since the surface area is higher, there's:
a) A higher chance that the pieces burn up in the atmosphere (this happens all the time).
b) Less damage since the resulting pieces don't have the same amount of kinetic energy (Would you rather be hit by a car going 20 MPH, or a bicycle going 20MPH?). There have been numerous stories of meteors falling out of the sky and punching a hole in a roof of a building with no other damage. Surely you'd rather pay to fix everyone's roof than have all life on Earth wiped out.
-- Ever notice that fast-burning fuse looks exactly the same as slow-burning fuse? I didn't... (Edgar Montrose)
The last major climatic event (being Krakatoa going bang) in the dark ages was probably responsible for the death of King Arthur.
Eh? What are you talking about with the dark ages? Krakatoa started being active in May 1883, with the final explosive eruption of Krakatoa taking place on August 27 1883. The force was equivalent to that of a 100 megaton bomb, some 5000 times more powerful than the Hiroshima nuke.
There's more information on it here at NASA.
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Jon E. Erikson
Jon Erikson, IT guru
Ok, you find a dinosaur killer on a collision trajectory with the Earth. It will hit us in 18 months. What do you do now?
:-).
It looks like the only technology that could possibly pack enough energy to deflect an object with such momentum is a nuclear bomb. Isn't it ironic that the same technology that brought us the possibility of destroying life on planet Earth could also save it?
A few years ago I did a few back-of-the-envelope calculations to see what would be required to deflect an object a few kilometers in size. Naturally, the delta-V you need to deliver depends on how early you can catch it. If it's still very far you need just a little nudge to ensure it won't collide. It also depends on what margin for error you want to tolerate i.e. how far from Earth do you want it to pass.
It looks like some of the bigger H-bombs have the energy to do it. The problem is how to convert it efficiently to kinetic energy. If you blow up a nuclear bomb in space all you get is a fantastic flash. The relatively small mass of the device itself evaporates and disperses into the vacuum in a matter of milliseconds. You need mass to convert this energy into motion. Using the mass of the asteroid itself is dangerous - if you blow up your bomb too close to the object it could break into many fragments with different orbits. Many of them could still hit the Earth. Splitting it neatly in half Armageddon-style is not very likely
So you need to bring your own reaction mass. The bomb will be accompanied by some big tanks of water. I don't remember the calculations, but you need quite a lot of reaction mass. It appeared to be more than what current launch vehicles can handle.
Have a nice day.
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Stop worrying about the risks of nuclear power and start worrying about the risks of not using nuclear power.