Saving Earth from asteroid and comet hits

[amshak]

An U.F.O. collided with Tungushka Astroyed [In Siberia] to save Earth .
Is this true?

 

[Couerl]

He's going to need a lot of "ballast" to make any appreciable difference in the trajectory of a 1km rock or greater.

 

[a_lost_packet_]

He's going to need a lot of "ballast" to make any appreciable difference in the trajectory of a 1km rock or greater.

It depends on how much time on station it has. Even a relatively small amount of mass can change the course of a very large asteroid if it has enough time to act on it.

 

[Couerl]

He's going to need a lot of "ballast" to make any appreciable difference in the trajectory of a 1km rock or greater.

It depends on how much time on station it has. Even a relatively small amount of mass can change the course of a very large asteroid if it has enough time to act on it.

Sure, but that can translate into 100's of years lead-time pretty quick and the likelihood of being able to identify a trajectory/threat out that far is relatively slim. Lot easier to sink some bunker busters 6 stories deep in whatever given body (something at least feasible near-term and within the realm of potential ability) and let the nukes do the rest. Like MW stated earlier, it depends entirely on the kind of rock we're talking about and mass and when it is spotted etc.. At a certain point or with a certain makeup it wouldn't matter what you did.. If we had a 1-3km rock that was fairly solid and sunk a nuke in to the surface (doesn't need to go too deep) and detonated it at the right moment it would nudge even a large parent body considerably and perhaps blow off a surface cap around a city block wide (give or take). Once the main body was deflected another nuke or two could finish off whatever else was left.

 

[SpacexULA]

Sure, but that can translate into 100's of years lead-time pretty quick and the likelihood of being able to identify a trajectory/threat out that far is relatively slim. Lot easier to sink some bunker busters 6 stories deep in whatever given body (something at least feasible near-term and within the realm of potential ability) and let the nukes do the rest. Like MW stated earlier, it depends entirely on the kind of rock we're talking about and mass and when it is spotted etc.. At a certain point or with a certain makeup it wouldn't matter what you did.. If we had a 1-3km rock that was fairly solid and sunk a nuke in to the surface (doesn't need to go too deep) and detonated it at the right moment it would nudge even a large parent body considerably and perhaps blow off a surface cap around a city block wide (give or take). Once the main body was deflected another nuke or two could finish off whatever else was left.

There is a reason why nuclear weapons are usually not seriously considered, and slow pushing is. Nuclear weapons don't work nearly as well in space as they do on earth. Why do you think we test nukes underground?

If you sink your nuke 6 stories into a 30-40km rock like produced the Shiva crater, it's not going to do more than give it a hair cut. Also the force impacted on a rock of that size by a nuclear weapon in space is TINY.

Even something on the Scale of Tsar Bomba, driven 10km into a 40km asteroid would not be sufficient to significantly alter the course of the matter to hit the earth. It would only serve to decrease the damage to the tectonic plate on impact.

The energy levels involved in 30km orbital bodies makes nuclear weapons look like fire crackers. It's like trying to play cricket with a bowling ball.

 

[SteveCNC]

if all else fails

 

[Couerl]

Sure, but that can translate into 100's of years lead-time pretty quick and the likelihood of being able to identify a trajectory/threat out that far is relatively slim. Lot easier to sink some bunker busters 6 stories deep in whatever given body (something at least feasible near-term and within the realm of potential ability) and let the nukes do the rest. Like MW stated earlier, it depends entirely on the kind of rock we're talking about and mass and when it is spotted etc.. At a certain point or with a certain makeup it wouldn't matter what you did.. If we had a 1-3km rock that was fairly solid and sunk a nuke in to the surface (doesn't need to go too deep) and detonated it at the right moment it would nudge even a large parent body considerably and perhaps blow off a surface cap around a city block wide (give or take). Once the main body was deflected another nuke or two could finish off whatever else was left.

There is a reason why nuclear weapons are usually not seriously considered, and slow pushing is. Nuclear weapons don't work nearly as well in space as they do on earth. Why do you think we test nukes underground?

If you sink your nuke 6 stories into a 30-40km rock like produced the Shiva crater, it's not going to do more than give it a hair cut. Also the force impacted on a rock of that size by a nuclear weapon in space is TINY.

Even something on the Scale of Tsar Bomba, driven 10km into a 40km asteroid would not be sufficient to significantly alter the course of the matter to hit the earth. It would only serve to decrease the damage to the tectonic plate on impact.

The energy levels involved in 30km orbital bodies makes nuclear weapons look like fire crackers. It's like trying to play cricket with a bowling ball.

Hi, The reason slow pushing isn't practical is because of the amount of lead-time needed to divert a 30km rock. We are talking about thousands of years most likely in this case and that is why it isn't likely to occur. Nuking a rock on it's surface in space would of course be useless, but exploding one below the surface is another story. If you blow up a firecraker next to a billiard ball you might barely nudge it. Try taping the firecracker up against the ball and then putty that over and explode it and the putty cap will blow off and the ball will roll all the way across the table. It's simple physics my friend and that is why we use shaped charges. The force of the explosion can be focused to provide the desired effect. In any case, something 30km coming this way any time in the next hundred years will simply kill us all in all probability

 

[MeteorWayne]

A couple of incorrect things there Couerl. First of all, with a 30 year lead time, a very small push in the right direction will ensure the earth and object are just not at the same place at the same time.. You don't have to change the orbit very much, just the timing.

As far as the firecracker taped to a billiard ball, great, except the billiard billard ball is the size of a baseball stadium. The effect of the firecracker is almost imperceptably small.

 

[Couerl]

A couple of incorrect things there Couerl. First of all, with a 30 year lead time, a very small push in the right direction will ensure the earth and object are just not at the same place at the same time.. You don't have to change the orbit very much, just the timing.

As far as the firecracker taped to a billiard ball, great, except the billiard billard ball is the size of a baseball stadium. The effect of the firecracker is almost imperceptably small.

Hi Wayne, I've heard several arguments and sure, a firecracker isn't going to move Fenway Park, but a 10 megaton nuke is not a firecracker. I suppose what it all boils down to is force and time. Give me 1000 years notice or even 30 and a small amount of mass will perhaps change the orbit of a 30km rock enough to do as you say. The problem is still identifying the threat in time and if Shoemaker Levy taught us anything it's that things that we don't anticipate can happen very quickly in our solar system. If we suddenly discovered something that large coming at us with say a year or two lead time we wouldn't have any choice other than to convert and launch everything we could put together against it and the sooner the better. The orbit as you well know also plays a significant role in any theoretical deterrence.. I'm not convinced by any means that we could have averted Shoemaker levy from hitting Jupiter even with 1000 years head start for instance, but perhaps there is at least enough data from that event to put together some reasonably accurate modeling, I don't know if anyone has tried yet...

 

[MeteorWayne]

A few comments. first of all for an impact less than a decade away, there's nothing we can do. We don't even have the capability to launch a bunch of nukes to LEO (at which point they would be worthless for an incoming asteroid...travel time to the surface 10-30 seconds), much less to intercept something further out with more lead time.

So it this point, we need to find rocks with our name on it with enough lead time so we can use other methods (such as gravity tugs, laser ablation, albedo alteration, and maybe even a well placed single nuke) to make a tiny change in orbital velocity.

My point of the firecracker and Fenway (How did you know I was a Yankee fan...nah just kiddin' It's a great old park) is that a nuke would have the same effect on an asteroid as a firecracker would have on something the size of a stadium.
IOW, not much.

Wayne

 

[ZenGalacticore]

A few comments. first of all for an impact less than a decade away, there's nothing we can do. Wayne

MeteorManWayne- Hey. I was just wondering if someone could post some actual graph/statistics about the odds of a serious impacter colliding with the Earth; say, in the next 10,000 or 100,000 years.

I think it would be pertinent.

 

[MeteorWayne]

Hmmm, the number is buried in one of the papers or sites I've posted before. You'll have to give me a little time to find it again.
Basically there is a background risk from unknown/undetected asteroids.

All known asteroids are many orders of magnitude lower in risk over the next century, which is as far as Sentry and NEODyS can run the calculations with current computer power in a reasonable time.
A few of the more hazardous ones have had it extended to 200 years, and one object, 1950 DA has been tracked for scores of years so the prediction goes about 800 years into the future.
Beyond 1000 years, asteroid orbits are not predictable, just as planetary orbits really aren't either. Any system with more than 2 objects has uncertainty that grows over time and becomes "chaotic" to varying degrees.

I'll try and find the background risk when I have time, hopefully tomorrow.

Wayne

 

[Fallingstar1971]

how about a simple space bound reflector telescope used in reverse?

I was playing around the other night and for giggles shined a flashlight through the EP and had the light emit from the OTA.

It was a pretty impressive light beam for a 2 dollar flashlight.

Now use the sun as a light source instead of a flashlight and tighten the focus.

With a big enough primary, you should be able to focus all the power you need..........

Any thoughts?

Star

 

[ZenGalacticore]

Hmmm, the number is buried in one of the papers or sites I've posted before. You'll have to give me a little time to find it again.
Basically there is a background risk from unknown/undetected asteroids.

All known asteroids are many orders of magnitude lower in risk over the next century, which is as far as Sentry and NEODyS can run the calculations with current computer power in a reasonable time.

Okay, well, despite the unknown asteroid factor, and that the computers can only do so much, let's use our minds instead. Without computers, we can look at recent human history. And by "recent", I mean the last 5,000 years. Besides the Tunguska Event--which was really a relatively minor impactor-- how many really serious and/or lethal impacts has the Earth suffered in the last 10,000 or 100,000 years?

I know of no historical record (in the last 5,000 years) of any impactor causing any kind of widespread destruction. Heck, even though the Tunguska impactor--probably the shard of a comet-- was felt as far away as London, it wasn't, TMK, felt outside of Asia and Europe.

And let's consider Meteor Crater in Arizona. That meteor impacted, IIRC, 50,000 years ago. (It may have been 20,000 years ago, can't remember.) But still, that begs the question of what are the odds of something much bigger than the meteor that casused Meteor Crater colliding with the Earth in the next 10,000 years? I think we can take comfort in those odds.

And if this kind of scenario of serious impactors happened at a rate of more than one every 10,000 years, or even one every 100,000 years, then human life, and really more importantly life itself, would never have been able to survive on any higher level and be here today blogging this message.

 

[MeteorWayne]

It is true there have been no "major" impacts in recorded history. But odds are a funny thing...just because the odds are 1 in 100,000 that something might happen this year, doesn't mean it can't happen twice this year

BTW, Meteor Crater's impact was ~ 49,000 years ago.

MW

 

[ZenGalacticore]

It is true there have been no "major" impacts in recorded history. But odds are a funny thing...just because the odds are 1 in 100,000 that something might happen this year, doesn't mean it can't happen twice this year

BTW, Meteor Crater's impact was ~ 49,000 years ago.

MW

49 thousand years ago. Very kick-but!


Now about that "odds" thing. If one buys one Mega-Millions ticket, his chances of getting all five #s plus the "Powerball" # are something like 80,000,000 (-for the viewers: 80 Million. Eighty-Million) to-one-odds against!

I'm of course not saying that a major impactor couldn't smack the Earth point-blank next Saturday. I'm just saying that the odds are against it. (Don't forget the old numbers, MeteorManWayne.)

 

[captdude]

The energy released from a loose impactor verses a solid impactor of the same mass might be the same from a physics standpoint - but the effects locally would be quite different. A loosely held comglomeration of mass entering our atmosphere would fail to impact the earth with much "cratering" force at all. Instead what we would see is a Tunguska type event as the loosely held together impactor converted most of its mass into energy several miles above ground zero. (The explosion at Tunguska is believed to have been caused by the air burst of a large meteoroid or comet fragment at an altitude of 3.1–6.2 miles above the Earth's surface)
There would be far, far, less particulates thrown into the atmosphere in comparison to a solid impactor and generally more conducive to the survival of the human race I would think.

 

[neilsox]

Blasting the impactor gives fair to poor results in most scenarios. An intruder is one million times a million cubic meters = several trillion tons. If the blast produces a million times a million = optimistic separate peices, they average one cubic meter = several tons, each, average. Some of the pieces are much larger and can easily kill everyone in a large city. Comparatively few would have died (near term) if the whole trillion cubic meters hit in a thinly populated area. Possibly the whole impactor might miss earth, resulting in zero deaths. A trillion cubic meters is equivelent to a cube 10,000 kilometers on an edge = ten kilometers. The arithmetic is not much better for several times smaller impactors. If the blast only produces a million peices, many of them are capable of totalling a large city, so total deaths are likely higher than the impact of the whole impactor. Neil