Can asteroids be stopped?

[Waymarker]

I mean, suppose astronomers spotted a really big asteroid (several miles wide) on a direct course to hit the earth, could we blow it up with nuclear missiles?
There'd be no blast wave in airless space to disintegrate it would there?
Maybe a high-explosive warhead would be better, or would there be no blast wave with HE too?

[Bob]

it wouldn't work. At best you'd turn a rock into rubble, many asteroids are already rubble, so it becomes the equivalent of a shotgun blast. The mass of a several miles wide asteroid would be so much greater than a nuke blast could effect.

[Zer0th]

It should be doable given enough notice.

As above, you don't want to turn the asteroid into a shotgun blast. Better to nudge its orbit a little. An ion thruster (http://www.nasa.gov/centers/glenn/about/fs21grc.html) landed onto the asteroid could do the job given sufficient time, imo.

It would be a nice world-unifying project.

[Tsunami]

Imagine the funds needed! That, I think could be the world unifying, when they all pool money together.

[GP100]

Yes, they could be stopped. We have / could have the technology to pursue any number of avoidance methods.

But, right now they would NOT be stopped because we are not pursuing the methods seriously enough at all.

[Waymarker]

But what would be the effect of a nuclear blast on it?
Would it be guaranteed to vapourise or disintegrate it?
For example at atomic test sites the ground is hardly damaged at all, so would a nuke blast really have the oomph to vapourize a mile-wide asteroid?

PS- Re disintegration, wouldn't that be good, bearing in mind most smaller bits would burn up when they hit earth's atmosphere?

[Garry Denke]

A R M A G E D D O N

iq6q2BrTino
Harry Stamper

[lycanox]

But what would be the effect of a nuclear blast on it?
Would it be guaranteed to vapourise or disintegrate it?
For example at atomic test sites the ground is hardly damaged at all, so would a nuke blast really have the oomph to vapourize a mile-wide asteroid?

PS- Re disintegration, wouldn't that be good, bearing in mind most smaller bits would burn up when they hit earth's atmosphere?

Well, the thing is that the asteroid itself would be the dominant source of gravity in the area. So even if you disintegrate it. The pieces would stick together if not given enough force. Turning the bullet into a shotgun.

Even if all the particles were the vaporise in the atmosphere. This would still result in heating the atmosphere to an oven, and the release of unwanted chemicals in it.

Offcource this is only an factor if we are talking about an head on collusion in days scenario. For an object discovered decades in advance. These methods would work as it would change its trajectory.

[Ningishiddza]

I mean, suppose astronomers spotted a really big asteroid (several miles wide) on a direct course to hit the earth, could we blow it up with nuclear missiles?

No.


There'd be no blast wave in airless space to disintegrate it would there?

Nope.

A blast wave from any explosive force is nothing more than compressed air. Explosions can be achieved chemically, through rapid oxidation (burning) or nuclear fission/fusion, but it doesn't change the fact that there is no air to compress.

Since there is no "atmosphere" in space, no blast wave. It would still produce light/heat.

In theory you could drill on the asteroid, plant a nuclear device and then detonate it. As the plutonium goes plasma and expands it would be like a balloon expanding, but the expansion isn't very great and not with much force, and very brief, just a few nanoseconds. The plasma has the same properties as gas/liquids, meaning it would seek the least path of resistance, so you'd have to plug the hole with something very solid, or the plasma would simply expand out of the hole without doing anything.

The heat might be sufficient to fracture a very small asteroid, but nothing in excess of a few kilometers in diameter.

The only possible way to alter the course of an asteroid is to affix a rocket motor to the asteroid and use it to push the asteroid out of the way.

The largest rockets on Earth are limited to a payload of a few thousand pounds. That's mainly due to Earth's gravity. Since there is little gravity in space, the rockets could handle a larger payload, but I have no idea how much larger.

Regardless, you'd need a cluster of rocket motors and sufficient fuel to burn long enough to affect the asteroid's trajectory.

Presently, no one has enough rockets, and there's no way to get them into space, and then get them to the asteroid and attach them, and there's no way there'd be enough time to do that, so it's a moot point.

[GP100]

Sadly, if an asteroid were coming this way soon, I think we'd be screwed. I say sadly because this is without excuse. We could have spent years by now setting up several avoidance methods -- in space -- to handle the problem.

As for a nuke, I would prefer to use one if we found an asteroid on path to hit us several several years from now. Not to blow it up, but to shift its course enough to make it miss us.

[Ningishiddza]

Sadly, if an asteroid were coming this way soon, I think we'd be screwed. I say sadly because this is without excuse. We could have spent years by now setting up several avoidance methods -- in space -- to handle the problem.

They could have done a lot of things, but they're too busy flat-dicking with stupid stuff. There is a slight glimmer of hope. They are starting to realize that asteroid impacts are far more frequent than they ever imagined possible, and perhaps that will spur them to action.


As for a nuke, I would prefer to use one if we found an asteroid on path to hit us several several years from now. Not to blow it up, but to shift its course enough to make it miss us.

You don't even have any nukes to shoot asteroids. Even if you did, you'd need a few 100,000 one megaton devices for a mere 1 in a 300 Billion odds of success.

You do realize that asteroids are moving at about 17 km/s right?

That's about 38,000 miles per hour, a lot faster than your ICBMs move.

And the mass? Well, do the math. One nuke would be like shooting a B-B gun at a car moving 60 mph and hoping the car will stop.

[Waymarker]

Fireballs are all over youtube and although spectacular they all seem to burn up and leave a harmless scattering of pebble-sized fragments over a large area (although I believe a car in NY state was badly dented by a fooball-sized chunk once)
My question is this:- what's the average size of the meteors that burn up and disintegrate?
Is there a certain size beyond which they won't break up, eg 50 yards wide, 10, half a mile etc?
Another thing- why can't astronomers detect incoming smallish meteors long before they reach earth?
Like I said, they're fairly common but the first we know of their existence is when they burn up. I'd have thought they'd be easily visible when they're out in space in bright sunlight as white specks against a black background.

PS- i just found this vid of the 'car' meteor, 1992, Wiki says it broke up over Kentucky and a fragment hit the car in Peekskill NY-

aOyECK-3awo

STILLS- http://uregina.ca/~astro/mb_5.html

[lycanox]

You do realize that asteroids are moving at about 17 km/s right?

That's about 38,000 miles per hour, a lot faster than your ICBMs move.

And the mass? Well, do the math. One nuke would be like shooting a B-B gun at a car moving 60 mph and hoping the car will stop.
Actually we have already landed successfully on such objects. So technologically this is not a problem. Only the time needed to plan such a mission.

[Fut004]

No.
The only possible way to alter the course of an asteroid is to affix a rocket motor to the asteroid and use it to push the asteroid out of the way.


Well that's not true.

I was watching a show not too long ago (The Universe, or The Known Universe or something) and they showed how an Earth/Moon Based Laser could be used to slightly alter the course of incoming asteroids. We're not talking about large alterations or anything, but enough that we'd be able to deflect the object away from us.

[palerider]

Erm what about momentum? Such a huge rock/slab, with a large mass would gather massive momentum.

[Ningishiddza]

Well that's not true.

I was watching a show not too long ago (The Universe, or The Known Universe or something) and they showed how an Earth/Moon Based Laser could be used to slightly alter the course of incoming asteroids. We're not talking about large alterations or anything, but enough that we'd be able to deflect the object away from us.

They're full of shit. What, deflect it so it hits Newark instead of New York?

That's just a theory someone has. If you could use LASERs to deflect objects, they'd be using them air defense weapons.

The average mass of an asteroid is 1.47 x 10^15 kg, which is

1,470,000,000,000,000 kg.

If you can deflect an asteroid weighing 1,470 TRILLION kg (which is 1.617 Billion tons) moving at 17 km/s, then you can obliterate a 14-ton F-16 moving at 530 knots.

[Fut004]

They're full of shit. What, deflect it so it hits Newark instead of New York?

You know, just because you're reading something new, it doesn't mean it's automatically "full of shit". Just saying.

Anyhow....



The Earth has been bombarded by asteroids in the past, and it’s going to happen again in the future. It’s not a question of “if”, it’s a question of “when”. Keenly aware of the problem, scientists are working on strategies that could prevent an asteroid with Earth in its cross hairs from impacting us.

One interesting technique is being worked on at the University of Alabama in Huntsville. The strategy would involved placing a laser system into space, or at a future Moon base. When a potential Earth-crossing asteroid is discovered, the laser would target it and fire for a long period of time. A small amount of material would be knocked off the surface of the asteroid, which would deflect its orbit slightly. Over a long period of time, the asteroid course correction would add up, turning a direct hit into a near miss.

A laser system like this is a long way off, but a system could be developed sooner that could focus on asteroids and help measure their properties and precisely track their orbits, helping remove some of the uncertainty.

Lasers Could Deflect Future Asteroids From Impacting Earth (http://www.universetoday.com/1321/lasers-could-deflect-future-asteroids-from-impacting-earth/)


According to the research, diverting objects such as these is a better option than exploding them as the debris itself could bathe Earth in a radioactive shower.

Matloff and his colleagues have been experimenting with red and green lasers to see how deeply they penetrate asteroidal rock, using solid and powdered (regolith) samples from the Allende meteorite that fell in Chihuahua, Mexico in 1969.

His study indicates that an asteroid could be diverted by heating its surface to create a jet stream, which would alter its trajectory, causing it to veer off course.

And to do that, one needs to know how deeply the light would need to penetrate the Near Earth Object's (NEO) surface.

"A beam that penetrates too deeply would simply heat an asteroid but a beam that penetrates just the right amount - perhaps about a tenth of a millimeter - would create a steerable jet and achieve the purpose of deflecting the asteroid," said Matloff.
Study suggests lasers could help deflect asteroids (http://www.dnaindia.com/scitech/report_study-suggests-lasers-could-help-deflect-asteroids_1501703)

I'm still looking for clips from the actual show I was talking about before, but I'm not having any luck at the moment. I might have to get a copy of it and upload it myself.

In the meantime though, let's all look at various ways to deflect asteroids that people are coming up with:

This video is about an hour long, and I haven't watch much of it yet. I'm sure they'll mention the laser / sunlight idea in it though. If anybody sits through this and finds the section, can you post the time for the rest?
-VU5R-x24Wc
________
Edit:
Alright, so he barely talks about Deflection at all. Skip ahead to about 36:30mins. He mentions how slighting changing the speed of an incoming asteroid, either by slowing it down, or speeding it up, can make it miss the Earth.

Still looking for info about the Lasers though.
________



That's just a theory someone has. If you could use LASERs to deflect objects, they'd be using them air defense weapons.


Ummm.. They are starting to use lasers for air/ground/sea defense. Although, they're typically used to destroy the incoming threat, not simply deflect them.

[The Mule]

Rather than spending billions (probably trillions) on a space weapon, could it be possible to increase Earths own defences by altering its own atmosphere in some way ?

Currently objects of a particular size 'burn up', therefore surely the logical route is to increase the efficiency of earths own defences so that it is able cope with much larger objects.

[Fut004]

Rather than spending billions (probably trillions) on a space weapon, could it be possible to increase Earths own defences by altering its own atmosphere in some way ?

Currently objects of a particular size 'burn up', therefore surely the logical route is to increase the efficiency of earths own defences so that it is able cope with much larger objects.

Thinking outside of the box, I like that.
This is just a guess, but I don't think we'd be able to modify our Atmosphere without changing the conditions on Earth. Also, I'd imagine that doing so would cost a shit-tonne of money anyhow.

[Vuall]

If it's thinking outside the box you want, someone ought to try telekinesis, maybe it would work better in space where there is no atmosphere to distort it.

[lycanox]

Rather than spending billions (probably trillions) on a space weapon, could it be possible to increase Earths own defences by altering its own atmosphere in some way ?

Currently objects of a particular size 'burn up', therefore surely the logical route is to increase the efficiency of earths own defences so that it is able cope with much larger objects.

The air pressure of a atmosphere dense enough to burn up everything would crush everything. Not to mention it would not do anything about the energy in the projectile. So you would still get a deadly and hot shock wave.