Is there realy anything we can do about it.

Lets say we detect it now, and its calculated to enter the earth atmosphere in 5 years.

Approx 10 kilometers in diameter.

What would we do!!

Im convinced that we must try something,but what?

I know there is only a slim to none chance that would ever happen,,,,,

BUT NOT IMPOSSIBLE RIGHT??

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I still await the compelling Exhibit A.

Abandoning it all and have a 5-year party.

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I think five years is far too short a warning time for an asteroid, you'd need decades.

We also need to see what the engineering upper limit yield is for nuclear weapons. The biggest one tested was something like 60 megatons. You can't just pack in more hydrogen in to increase the yield because the bomb destroys itself before all the hydrogen can fuse. So you might need many nukes to do the job.

We also need to know the structure of the asteroid - whether it is made of ice or iron-nickel will make a big difference. Is it a solid lump of matter or several smaller bodies loosely held together?

There are other ideas like autonomous asteroid-eating machines that will change its mass enough to alter its course. That, or gigantic rockets to push it off course.

It would probably be wise sometime in the next decade to build and test one of these ideas on an actual asteroid.

Changing its mass wouldnt nessesary alter the asteroids course.!
And what if its made of iron....DEEP IMPACT scenario....dig and hide?

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I still await the compelling Exhibit A.

Surely the empahasis should be on deflection rather than destruction? We only have to get it to miss the Earth, not shower us in fragments of uncertain size and radioactivity. On that basis the earlier the detection the smaller the nudge required to redirect it. Five years is a short time to develop, launch and deploy any mission so if we are serious about this then a system would have to be in place now ready to use as soon as an orbit is confirmed as a definite hit. I would go for a number of smaller craft, it would give more flexibility wrt. size of asteroid and also backup should there be a failure.

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By asking questions we sometimes get the wrong answers, from wrong answers we learn to ask the right questions.

We are getting pretty good at finding NEOs. I'm guessing that a 10 km diameter object would be spotted well before it was 5 years out from hitting Earth. Anyone know for sure? I couldn't find specifics, but this page was interesting: NASA stats

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Atomic weapons would be used not to destroy the object, but to alter its course. Detonating a nuke hundreds of metres from the surface would vaporize a good chunk of the regolith around it. The vapor would then stream into space, creating a kind of nuclear-powered ion engine :)

Repeat as needed, on the same side of the asteroid, and you've got significant delta-v.

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A quick phone call to Bruce Willis?

Nick 8-[

Going back to the original post, finding a "new" 10 km asteroid is going to
be hard. We should have found those already. Note that the Near Earth
discoveries tend to be at most ~ 1 km, although I admit one of those
could ruin your whole day. I don't recall the size for a "Civilization Ending"
impact.

One of the (many) things that galled me about the Bruce Willis movie
was the asteroid "the size of Texas" coming at us. We would have seen
that in the 1800's. And please don't say it was coming in on a hyperbolic
orbit. Comets do that but we have yet to find any evidence of an asteroid
doing that, and good reason to believe they don't, at least not Texas-sized ones. :-?

I agree that something "the size of Texas" certainly isn't going to sneak up on us. However, you don't need something that large to still really ruin your day. Here's a good article that covers the subject nicely. The final summary:

The sky may not be "falling" but we shouldn't ignore this very real issue either.

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An open mind is like an open window...without a good screen you'll get all sorts of weird bugs!

I'd actually bet that given a five year concrete warning we'd come up with, and successfully execute, a plan of some sort. Perhaps several different methods would be tried in parallel. But given an impending crisis, a lot of resources and funding would be thrown at the problem, and it's often pretty impressive what we can achieve when we do that, and how quickly we can do it. Think about the Apollo program or the work done at Los Alamos. I'm not saying it would be easy, but I think we'd manage something.

They'd probably rush another ho-hum Delta II into production--dispose of its GPS/MARS/GOES payload, jerry-rig it with a nuke (with or without a simplified NEAR package) and hope for the best.

If we had enough warning, say 10 years or more, it wouldn't take much to cause a miss.

A mission to paint half of the asteroid with white or black paint would do alter the orbit slightly over a long enough period.

Lots simpler than trying to blow up something that probably would be a gravel pile (some asteroids are, some aren't) anyway.

OK. Lets think. Human logistists.

UK e.g. has a population of 60 million people or near abouts. Suppose half the people in the UK today had an egg, or ate something made with an egg as an ingredient. That is 30 million eggs -> A day.

Now, suppose a small impact hit a farming belt in UK, or USA or wherever. The logistists train gets broke big time.

Very quickly, and very urgently things break, as really we all live in a modern society relying on automatic resource, and the line is very thin - much like a drought can bring down a whole nation.

3rd world countries (Africa, India, inland China) will not be so affected by this 'logistists train', but they have their own problems anyway.

Nick

"OK. Lets think. Human logistists.

UK e.g. has a population of 60 million people or near abouts. Suppose half the people in the UK today had an egg,
Nick"



I simply just dont get that last one...... 8-[

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I still await the compelling Exhibit A.

It may not be eggs. It could be bread, or water, or anything that needs to be supplied (i.e. grown/produced/procurred) on a mass quantity daily to a population of large numbers..

A slight disruption to the logistics train quickly upsets the whole thing into chaos -> overload.

Nick

Hey, all we have to do is to get everyone in China to jump at the same time.. Oh, wait, that's a different BBS.

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When I am done here I think I will go create something from metal.

can't we use the moon as as 'shield', try to force the astoroid to crash on the moon.

or would that give to many debrie and possibly chuncks of moon falling towords us,

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The moon does shield us to some extent but it can't cover every portion the sky. Forcing the asteroid hit the moon instead will still require a large amount of effort in a short period of time. I don't think there is any real danger of chunks hitting us afterwards, some debris will eventually make it.

Five years is plenty of warning to do *something*. Whether a mass driver could be designed, built and launched in time is questionable. Maybe with full global resources it could be.

Nuclear weapons would definitely work if used in a stand off detonation. It simply needs nudging off course. In space there is no atmosphere, hence no blast wave -- just heat and radiation. A stand off detonation would vaporize a layer of material, nudging the asteroid the opposite direction.

Existing ICBMs can reach escape velocity if stripped down to one warhead. The existing warhead "bus" already has substantial maneuvering ability. It would only need an additional guidance package to enable a precision stand off detonation. That could be ready within weeks.

One problem is the warhead is "only" 300-400 kilotons, so likely multiple shots would be needed. However there are 50 Peacepeepers and 264 Trident II D-5 missiles available, so multiple shots would be possible. The Russian force would presumably also be available (it's a global problem).

Much larger warheads are available, up to 20-50 megatons and launchers could lift those if necessary but it would take many months to get ready.

A high confidence approach would be needed, as a 10 km asteroid impacting at 17 km/sec (a typical speed) would be equivalent to a 54 million megaton bomb. It would destroy any structure within a 1500 km radius, and would probably cause drastic climate changes.

5 years at 17 km/sec puts the detection distance at 2.68 billion km (roughly the orbit of Uranus). From that distance it would only require deflecting 1/2 arc second. If intercepted about halfway to Jupiter (1 billion km) it would still only require 1.31 arc seconds deflection.

You obviously want to deflect it as early as possible, not wait several years for the best possible technique.

A 10 km astroid is 510E9 cubic meters. If composed of dense rock (3000 kg/m^3) it would weigh 1.53E15 kg. If detected at 5 years out, and deflected at about 2.5 years out (roughly 1 billion km), it would only require 8 cm/sec lateral deflection. This would require 4.89E12 joules or 1.35 gigawatt hours energy. Probably a mass driver could do it, assuming it could be designed and built in time, along with the power source and booster. Nukes could easily do it.

Considering the entire world would be at risk, you'd probably want multiple parallel approaches to ensure something worked.

It would probably be best to set the bomb off in front of or behind the big rock, correct? Otherwise there might not be a big enough effect on its orbit. If we were lucky, maybe we could catch it at its periapsis, where the blast would have the greatest effect.

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Moraliser Overtax Porn

joema!!

I hope that your serious and and that your math is correct!!

But do we have a good beat on ALL of them,like the ones you hear about.....Comming from the direction of the sun(as in-- we cant se them).

Or is that just some urban legend thing that got stuck under my shue?? #-o

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I still await the compelling Exhibit A.

Well, in order to come from the direction of the sun (aka between us and the sun) and still hit us, the object's orbit would have to still cross our orbit. Which means that, at some point in the past, it was outside our orbit and potentially opposite the sun, and thus easily detectable :)

So no, this really isn't something to worry about, at least for very large asteroids (10km is VERY large).

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Either a mass driver or a nuke forcing it any direction would make it miss. Since its trajectory must intercept the earth in three dimensions and earth is orbiting the sun at 29.5 km/sec (66,000 mph), slowing the asteroid down or speeding it up slightly would cause a miss. Obviously a lateral deflection would also cause a miss.

Careful study would pick the deflection vector that requires the least delta V and is most likely to achieve the goal. Depending on the asteroid/earth intercept angle, either a lateral or longitudinal deflection could be the lowest delta V.

For an asteroid impact perpendicular to earth's orbital motion, it appears the lowest delta V is speeding the asteroid up or slowing it down about 4.6 cm/sec at an intercept distance of 1.34E6 km, 2.5 years out. This is about 1/2 the delta V required for a lateral deflection, about 8 cm/sec.

For an asteroid impact in line with earth's orbital motion, it appears to be more efficient to deflect it laterally about 8 cm/sec. However that's just from simple trig calculations.

Remember that the Earth is about 13,000 km in diameter, the Moon is about 3,500 km in diameter, and the two are 380,000 km apart, on average. So unless the asteroid was already on a course that would come very close to striking the Moon by chance (a pretty unlikely situation), it's actually a lot more work to get it to hit the Moon than just to miss the Earth.

So an ICBM can escape with one warhead?

Hmmm. Sounds iffy.

Sure they can. For best payload capacity you might also remove the inertial reference sphere, which is very heavy and not needed for an asteroid intercept mission. A Titan II ICBM launched the Clementine probe to lunar orbit, which is about the same delta V as earth escape velocity.

A Peacekeeper ICBM has more payload capacity than a Titan II.

As Peacekeeper ICBMs are decommissioned, they've been considered for general purpose launch vehicles. In addition to eliminating the warheads, eliminating or replacing the heavy military hardware such as the inertial reference sphere and post-boost reaction control would further increase the payload capacity:

http://www.asdl.gatech.edu/publicati...-2002-5854.pdf

[quote=" So unless the asteroid was already on a course that would come very close to striking the Moon by chance (a pretty unlikely situation), it's actually a lot more work to get it to hit the Moon than just to miss the Earth.[/quote]

That would be some serious fireworks,if it hit the moon..!!! 8)

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I still await the compelling Exhibit A.

Coul it be a ten Km comet?

Heck, I'm not even worried about asteroids when a meteorite can mess up your day! The asteroids can come when I'm living on another planet...well, come to think of it, I may already be there.

This was sent to me in an email titled "Year in Pictures." I don't know what year or the source, but I've tried to find it with no luck. It doesn't seem PhotoShopped, but I don't know. Anyone know? I've always wanted a rock sculpture in my living room.


http://pub22.bravenet.com/photocente...num=1805537384


Edited: I hate Bravenet! Blame it on the Canadians--they're in B.C. Just kidding, I luv Canadians :-)

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