Nuking an incoming asteroid is a daft idea - as all NASA's plans seem of late

[SUBMAN1]

I've known about this for some time. The only time a nuke might prove useful against an asteroid is when the object is completely solid / dense, like made out of iron. If the object is loosly held together, then a nuke will just make the problem worse!

This brings me to my point - NASA. I am increasingly loosing faith in this organization. I think it is corrupt. I think it will say what people want it to say with little regard to science. I think they will say whatever the politicians want to hear.

NASA needs to be closed and then reborn as something new with a focus on science. It is no longer a respectable agency the way it is. Yes, they can still launch things, but that is about all they can do. Science was forgotten long ago.

And the funny part - NASA can't understand why they are losing budget? It comes down to this - you feed crap science to the public, Joe Blow public is not so stupid and will eventually figure it out. When this happens, Joe Blow public eventually doesn't care what NASA says or does. When this happens, politicians start not carring about NASA. NASA continues to spin BS to the politicians to maintain funding, but at this point it is already too late - they are a dying organization. Then NASA ends up a relic of the past at some point. I thought NASA scientists were supposed to be smart? Well, seems they missed this basic chain of events. Makes me wonder if they can do any other real science at all? Or are they just relying on technology from the past? Sad.

I have no faith in NASA anymore. To me, they are turning into a major disgrace.

At least their past Astronauts still have a brain.

-S


Nuking an incoming asteroid is a daft idea

Says a man who knows

By Egan Orion: Monday, 28 July 2008, 10:58 AM


APOLLO ASTRONAUT Rusty Schweickart differed with NASA during a public lecture in San Francisco last Wednesday by opining that using nuclear weapons to deflect incoming asteroids isn't a very good idea.


The former lunar lander pilot said a NASA report that made that recommendation last year was misleading. He felt it was probably issued under political pressure to create some justification for putting nuclear weapons into earth orbit.


Schweickart said that asteroid-sized space objects might be deflected by pushing or towing them. He is member of the B612 Foundation, which aims to develop the capability to alter the orbit of an earth-crossing asteroid in a controlled manner by 2015.


Schweickart was too diplomatic to say it in so many words, but lobbing nuclear weapons at asteroids has the potential to break the target into pieces.


When comet Shoemaker-Levy 9 broke apart due to gravitational tidal forces in 1994, at least 21 visible fragments that were up to two kilometres in diameter impacted Jupiter at speeds of approximately 60 kilometres per second.


Such a string of impact events would really ruin our whole eon here on Earth.

http://www.theinquirer.net/gb/inquirer/news/2008/07/28/nukes-bad-idea-stopping

[Jimbuna]

Do you remember a film perhaps ten years back (it was filmed in a news presentation style) where the earth was going to be hit by a huge asteroid ?

They nuked it and when everyone breathed a sigh of relief, suddenly three more appeared from deep space.

I believe they came within a whisker of collision with earth before SSBN's were used to destroy them.

Just as all the world started celebrating, radar picked up thousands of them and the transmission of the film ceased, giving the impression the world had been obliterated.....the end of the film.

[SUBMAN1]

Do you remember a film perhaps ten years back (it was filmed in a news presentation style) where the earth was going to be hit by a huge asteroid ?

They nuked it and when everyone breathed a sigh of relief, suddenly three more appeared from deep space.

I believe they came within a whisker of collision with earth before SSBN's were used to destroy them.

Just as all the world started celebrating, radar picked up thousands of them and the transmission of the film ceased, giving the impression the world had been obliterated.....the end of the film.I missed that one!

Anyway, thousands are out there now. Chances of one hitting is remotely small, but it will happen some day. Just hope its a small one, or that we have the capability to tow it out of the way!

Whats the name of it?

-S

[Seth8530]

was it Armageddon?

[SUBMAN1]

was it Armageddon?No - that was with the Shuttle and was a pretty bad movie.

-S

[Jimbuna]

Do you remember a film perhaps ten years back (it was filmed in a news presentation style) where the earth was going to be hit by a huge asteroid ?

They nuked it and when everyone breathed a sigh of relief, suddenly three more appeared from deep space.

I believe they came within a whisker of collision with earth before SSBN's were used to destroy them.

Just as all the world started celebrating, radar picked up thousands of them and the transmission of the film ceased, giving the impression the world had been obliterated.....the end of the film.I missed that one!

Anyway, thousands are out there now. Chances of one hitting is remotely small, but it will happen some day. Just hope its a small one, or that we have the capability to tow it out of the way!

Whats the name of it?

-S

I can't remember, that's why I asked :lol:

[XabbaRus]

Deep Impact?

[Jimbuna]

Deep Impact?

Nope....thereweren't actually any big names in it as I recall.

It was shot as a news release type.

[ASWnut101]

I've known about this for some time. The only time a nuke might prove useful against an asteroid is when the object is completely solid / dense, like made out of iron. If the object is loosly held together, then a nuke will just make the problem worse!

Unfortnately, even nukes wont help unless the incoming object is quite tiny (probably less than a kilometer in diameter, and is made mainly of ice, like a small comet). If any decent sized rock comes hurtling towards us, we are pretty much doomed (:dead:).

[SUBMAN1]

I've known about this for some time. The only time a nuke might prove useful against an asteroid is when the object is completely solid / dense, like made out of iron. If the object is loosly held together, then a nuke will just make the problem worse!
Unfortnately, even nukes wont help unless the incoming object is quite tiny (probably less than a kilometer in diameter, and is made mainly of ice, like a small comet). If any decent sized rock comes hurtling towards us, we are pretty much doomed (:dead:).I don't think so. All you need is advance warning and the capability to move it ever so slightly - less than a minor bit of a degree.

-S

[August]

I don't think so. All you need is advance warning and the capability to move it ever so slightly - less than a minor bit of a degree.

-S

And a nuke, detonated in it's path would not have that capability?

[SUBMAN1]

And a nuke, detonated in it's path would not have that capability?On a solid object it would. Not the other way around though - you would just break it up and it would continue on its path. Multiple impacts of smaller objects is much more devastating that one large object. This makes the problem worse, and more wide spread.

-S

[August]

And a nuke, detonated in it's path would not have that capability?On a solid object it would. Not the other way around though - you would just break it up and it would continue on its path. Multiple impacts of smaller objects is much more devastating that one large object. This makes the problem worse, and more wide spread.

-S

I didn't say detonate on the object but in front of it. IE between the object and the earth. It shouldn't matter whether it's a solid, liquid or gas.

[SUBMAN1]

And a nuke, detonated in it's path would not have that capability?On a solid object it would. Not the other way around though - you would just break it up and it would continue on its path. Multiple impacts of smaller objects is much more devastating that one large object. This makes the problem worse, and more wide spread.

-S
I didn't say detonate on the object but in front of it. IE between the object and the earth. It shouldn't matter whether it's a solid, liquid or gas.It makes a big difference in the models. There was never any want to impact it on the surface in the first place - and I am assuming you knew that, but maybe you don't. The full force of a nuke can only be felt if detonated at Alt. Same physics work here on Earth since any ballistic missile will detonate in the sky sending the force of the impact down. I will post models on that shortly if I can find them.

And it makes a huge difference in the models in that when asteroids were considered all completely solid, the nuke model works and it alters course. When the model turns to a lesss dense material such as a giant dirt clod (like my analogy?), the parts simply split into sections and continued more or less on the same course, resulting in multiple impacts. It is kind of like the blast wave simply goes through the object instead of against it.

-S

[SUBMAN1]

Here is the optimum burst altitude based on height for a desired PSI - represented by the doted line. This is based on a 1 kt (tiny) nuke explosion - suitcase size. The curves get way more dramatic as the kt gets bigger. Hiroshima was about 20 kt. The Russians have a 100 MT (100,000 times this curve) for comparrison purposes. Not sure if its still in inventory though. The Americans like 300 kt the best I think since they have more 300 kt bombs than any other type.

http://upload.wikimedia.org/wikipedia/commons/thumb/1/19/Blastcurves_1.png/800px-Blastcurves_1.png

http://upload.wikimedia.org/math/7/2/f/72fede5518a5d56d3dd3ec0153064cb4.png

[UnderseaLcpl]

I'm going to have to agree with subman that NASA is a waste. Recent ventures by private firms into spacecraft manufacture prove that NASA is incompetent and inefficient. Yes, we have gotten some great things from them in terms of scientific discoveries but I firmly believe a private organization could have gotten them cheaper and faster.

To this day I do not understand why NASA insists on using rockets to propel spacecraft into orbit. Why not simply fly into the upper atmosphere with conventional jet propulsion and THEN use rockets to escape earth's gravity?

As far as the nuking an asteroid thing goes, the prospects of success would be quite dubious. Firstly, the asteroid would have to be identified in time to develop and produce a suitable detonation mechanism. This is compounded by the fact that the intercept would have to take place tens if not hundreds of thousands of miles away to prevent Earth's gravity from sucking it back onto a collision course. A course change of only a very few degrees or even fractions of a degree would be possible. I'm no physicist but when you consider an object weighing hundreds of millions or even billions of tons is hurtling forward at tens or hundreds of thousands of miles per hour, that is quite a bit of inertia to overcome. The idea that even a 500-megaton explosive force could significantly alter its' course in all but the most favourable of circumstances is hard to believe.
As if that weren't enough the energy potential of a nuclear blast is reduced to its' minimum possible area of effect in space as there is no significant medium to transmit force through. Yes, the blast wave itself will be unimpeded, but consider the analogy of sound in air versus water. It travels much farther and even faster in water due to displacement of a significant medium.
It is possible that a string of nuclear detonations in succession could alter the course of an asteroid significantly, provided it has relatively little mass, but we still face the problem of detection and timely interception by appropriate weapons.

Our best defense, for the time being, against world-killing chunks of space rock is the impossibly slim chance they have of hitting Earth before cheap and effective countermeasures can be readily produced.

That's an uneducated jarhead's perspective.:D

edit_ I am pleased to see that in the time it took me to write this subman has posted a.........thing..... that I don't understand but which probably supports my hypotheses.

[SUBMAN1]

....edit_ I am pleased to see that in the time it took me to write this subman has posted a.........thing..... that I don't understand but which probably supports my hypotheses.Hahahaha! Actually it doesn't support it... Its pure data.

The best method right now is a simply solar mirror. Park a spacecraft off to the side of the rock and on the same course and simply channel sunlight into a specific area of the rock. Done long enough, the heat will simply push the rock off its present course and onto a new one. Its a simple and effective concept.

NASA though needs some serious restructuring.

-S

[August]

Doesn't support or detract from it one way or the other from what i can tell...

[SUBMAN1]

Doesn't support or detract from it one way or the other from what i can tell...Let me put it into laymens terms then. This is a military board, so we will use a 'bullet' as the analogy.

Go to the range, and you shoot up a solid metal block 1x1' (This represents the asteroid made of pure iron) sitting on a wooden stick (which represents its energy/mass/speed). The full energy of the bullet is transfered into that block and it will probably break the stick it is sitting on since no penetration occured. Course for our asteroid is now changed.

Move on the the range with the paper target (which represents the dirt clod style asteroid - which apparently is a very common form unlike what was previously though). The paper even sits straight up and down by its own weight in this case. Here the bullet has so much kenetic energy, it simply passes through the paper hardly doing anything to the paper at all. This same thing will happen with a nuke on the dirt clod - you won't change its course, but you will punch holes in it and break it up. Now it is many times more deadly as it hits the Earth. The point being, the energy did not pass into the paper to change its course, just like the nuke energy does not pass into the dirt clod asteroid to change its course.

Does that make sense?

-S

[ASWnut101]

Subman1:I don't think so. All you need is advance warning...

That's kind of the problem. We already know about all sorts of asteroids that come near Earth. And we know that pretty much all of them wont hit us any time soon. It's the ones that we don't know about that would kill us.

To successfully "move" an asteroid out of the way, you would need many tens of years of warning; and in many tens of years, that rock has moved many tens of orbits (or in the case of a comet, probably only none since its discovery). You would need the time for mission preparation, technology design (as I'll exlpain later, nukes simply aren't powerful enough), resource pooling, develop an "international plan" between the countries of the world, compile everything together, launch the rocket, wait the many years for it to acutally reach the target, and hope to high hell that it does something.


and the capability to move it ever so slightly - less than a minor bit of a degree.


Only if the asteroid/comet is sufficiently far enough away (very far). And if it's of any decent size (more than a few kilometers across), you can forget about any hope of moving it in time.



I didn't say detonate on the object but in front of it. IE between the object and the earth. It shouldn't matter whether it's a solid, liquid or gas.

Nope, nothing would happen (except a nice light show) unless the rock was inside the nuke's fireball at the time of detonation. Outside of the fireball, only radiation pressure is emitted. There would be no overpressure wave ("shock wave," which would only happen if the detonation happened in a medium [substance]. Space is a vaccum, and there is nothing to carry all that force beyond the fireball).



It makes a big difference in the models. There was never any want to impact it on the surface in the first place - and I am assuming you knew that, but maybe you don't. The full force of a nuke can only be felt if detonated at Alt. Same physics work here on Earth since any ballistic missile will detonate in the sky sending the force of the impact down. I will post models on that shortly if I can find them.


As I've explained to August, an "air-burst" (misnomer in space) over an asteroid would have almost no effect outside of the fireball. Those tests were conduced in the atmosphere, where the blast created an overpressure wave in the air.



And it makes a huge difference in the models in that when asteroids were considered all completely solid, the nuke model works and it alters course. When the model turns to a lesss dense material such as a giant dirt clod (like my analogy?), the parts simply split into sections and continued more or less on the same course, resulting in multiple impacts. It is kind of like the blast wave simply goes through the object instead of against it.


True, however, nukes simply aren't powerful enough. Besides the fact that we don't have any over the size of 10-20 Megatons (the biggest ever being the Russian Tsar Bomba, a 50Mt weapon), even a surface blast would not impart much energy into the asteroid (say, 3km across, a nice lower-than-average size for an asteroid). At most, it would create quite a nice crater. The asteroid would have a substantial amount of mass removed, but it would not destroy the rock.

Also, if a surface blast is conducted, the majority of the energy would be released into space as thermal energy. The overpressure wave in the rock itself would also not do much, except mabye a little physical deformation on the opposite side of the rock.


The only effective way to "move" the asteroid out of the way soon enough is with an engine (literally strapping a rocket engine to the asteroid). However, we do not have anywhere near the means to get such an engine in space, let alone to an asteroid. The sheer mass needed for it would dwarf anything currently built.


It's a sad proposition, but people must understand that should an asteroid be discovered on a terminal orbit with Earth, there is not much hope, if any.

[SUBMAN1]

....True, however, nukes simply aren't powerful enough. Besides the fact that we don't have any over the size of 10-20 Megatons (the biggest ever being the Russian Tsar Bomba, a 50Mt weapon), even a surface blast would not impart much energy into the asteroid (say, 3km across, a nice lower-than-average size for an asteroid). At most, it would create quite a nice crater. The asteroid would have a substantial amount of mass removed, but it would not destroy the rock.

Also, if a surface blast is conducted, the majority of the energy would be released into space as thermal energy. The overpressure wave in the rock itself would also not do much, except mabye a little physical deformation on the opposite side of the rock.


The only effective way to "move" the asteroid out of the way soon enough is with an engine (literally strapping a rocket engine to the asteroid). However, we do not have anywhere near the means to get such an engine in space, let alone to an asteroid. The sheer mass needed for it would dwarf anything currently built.


It's a sad proposition, but people must understand that should an asteroid be discovered on a terminal orbit with Earth, there is not much hope, if any.

You aren't looking to destroy the rock. Just to barely move it. The nuke could accomplish this. Even a minor one if enough advanced warning is given. However, this would only work on an extremely dense rock. That is what I've been getting at.

In the end, a long warning time and a solar mirror can do the job.

-S

[Oberon]

Do you remember a film perhaps ten years back (it was filmed in a news presentation style) where the earth was going to be hit by a huge asteroid ?

They nuked it and when everyone breathed a sigh of relief, suddenly three more appeared from deep space.

I believe they came within a whisker of collision with earth before SSBN's were used to destroy them.

Just as all the world started celebrating, radar picked up thousands of them and the transmission of the film ceased, giving the impression the world had been obliterated.....the end of the film.

http://en.wikipedia.org/wiki/Without_Warning_%281994_film%29

?

[SUBMAN1]

Cool software everyone should have!

Blast Software!

No abandonware

-S

[ASWnut101]

You aren't looking to destroy the rock. Just to barely move it. The nuke could accomplish this. Even a minor one if enough advanced warning is given. However, this would only work on an extremely dense rock. That is what I've been getting at.

:D What I've been trying to get at is that it can't simply be moved by a nuke. No nuke in existance has enough power to push it (3km rock) out of the way. The energy needed to move it even say, 15m/s, is extraordinarally high. And, for example, a 15Mt nuke detonated on the surface would not impart 15Mt worth of energy to the rock. Most of it gets lost as thermal energy in the vaccum of space.

Also, if anything, you'd want the rock to be less dense (which would imply less mass). The lower the mass of the object you are trying to push, the easier it will be. To be honest, though, I doubt a realistic nuke (surface blast) could even shatter an averaged sized comet, which is made of ice and dust.


In the end, a long warning time and a solar mirror can do the job.
-S

A very, very, very, very long warning time.

[ASWnut101]

Cool software everyone should have!

Blast Software!

http://nuclearweaponarchive.org/Library/Nukesims.html

-S


Nice find. Installing now...:up:

[SUBMAN1]

You aren't looking to destroy the rock. Just to barely move it. The nuke could accomplish this. Even a minor one if enough advanced warning is given. However, this would only work on an extremely dense rock. That is what I've been getting at.
:D What I've been trying to get at is that it can't simply be moved by a nuke. No nuke in existance has enough power to push it (3km rock) out of the way. The energy needed to move it even say, 15m/s, is extraordinarally high. And, for example, a 15Mt nuke detonated on the surface would not impart 15Mt worth of energy to the rock. Most of it gets lost as thermal energy in the vaccum of space.

Also, if anything, you'd want the rock to be less dense (which would imply less mass). The lower the mass of the object you are trying to push, the easier it will be. To be honest, though, I doubt a realistic nuke (surface blast) could even shatter an averaged sized comet, which is made of ice and dust.


In the end, a long warning time and a solar mirror can do the job.
-S
A very, very, very, very long warning time.You're missing the point. The change in direction can only be so tiny, its nearly immeasurable. All that takes is some energy / force however small acting in an opposite direction. E=MC2. You aren't ever going to change its direction, you are only looking to slightly alter its current and future course by a tiny tiny fraction. In the emptyness of space, this becomes huge over time.

You are only making it miss its target. Much like the wind can make a bullet miss its target given enough range in the shot. This is what the nuke, and even the solar mirror represents. In no way are you ever going to seriously alter the course of a massive rock. Even simply changing it a tiny fraction to one side, or slowing it down or speeding it up by a tiny fraction will do the job.

-S

[ASWnut101]

You're missing the point. The change in direction can only be so tiny, its nearly immeasurable. All that takes is some energy / force however small acting in an opposite direction. E=MC2. You aren't ever going to change its direction, you are only looking to slightly alter its current and future course by a tiny tiny fraction. In the emptyness of space, this becomes huge over time.

You are only making it miss its target. Much like the wind can make a bullet miss its target given enough range in the shot. This is what the nuke, and even the solar mirror represents.

-S

Let's be realistic here. This "tiny, immeasureable bit" of force would have to be imparted well in advance (well over 100 years away). The only problem is that our capeability for detecting relatively small objects is very small (we can only see those objects out to about 2AU, or 2 Earth-Sun distances). In the case of an asteroid, that may leave a few years. In the case of a super elliptical comet, that may leave as little as a half a year.

Say we were to discover an asteroid in the Main Asteroid Belt that would threaten earth in many years. Time would still be needed to further refine the observed orbital elements (orbital period, high point, low point, ect.). Why? Because our predictions and observations are not perfect. There are countless factors, some unpredictable, that affect the orbit of any body in the solar system.

That's the whole problem behind moving the asteroid/comet. Chances are, we are not going to have a long enough warning of an impending impact to be able to make a difference.

Take the supposed Mars-impacting asteroid from last winter. Astronomers had to wait until the rock was very close (within a month before 'impact') before making their final prediction on where the rock would pass (or hit) Mars. Even then they were not sure exactly where it would end up.

[SUBMAN1]

Let's be realistic here. This "tiny, immeasureable bit" of force would have to be imparted well in advance (well over 100 years away). The only problem is that our capeability for detecting relatively small objects is very small (we can only see those objects out to about 2AU, or 2 Earth-Sun distances). In the case of an asteroid, that may leave a few years. In the case of a super elliptical comet, that may leave as little as a half a year.

Say we were to discover an asteroid in the Main Asteroid Belt that would threaten earth in many years. Time would still be needed to further refine the observed orbital elements (orbital period, high point, low point, ect.). Why? Because our predictions and observations are not perfect. There are countless factors, some unpredictable, that affect the orbit of any body in the solar system.

That's the whole problem behind moving the asteroid/comet. Chances are, we are not going to have a long enough warning of an impending impact to be able to make a difference.

Take the supposed Mars-impacting asteroid from last winter. Astronomers had to wait until the rock was very close (within a month before 'impact') before making their final prediction on where the rock would pass (or hit) Mars. Even then they were not sure exactly where it would end up.The models don't show it like that. 100 years? Where did you get that? Try a year is good enough even for the solar device. In space, nothing is reacting with your rock except gravity. You as a man could eventually get a giant space rock to move with your bare hands given enough time and no counteracting force.

-S

[ASWnut101]

The models don't show it like that. 100 years? Where did you get that?

You said to move it only a "tiny, inmeasureable bit." And you would need to do that many years (ok, mabye 100 is a bit much) in advance to have a significant, safe change in its orbit by the time it comes near Earth. That's what I meant. Radiation pressure dosen't impart much energy on an object.

And you still have to add the fact that these "solar mirrors" that are capeable of focusing that kind of energy aren't even developed yet.

In space, nothing is reacting with your rock except gravity. You as a man could eventually get a giant space rock to move with your bare hands given enough time and no counteracting force.

-S

True, but only given that you are standing on something (to get it to move away from you), otherwise you both move. And then, it would be a lot of pushing... :)

[Zachstar]

What are you talking about? The solar mirrors have been developed. It is called thin foil....

With a small amount of weight you can make an area the size of a football field.

[SUBMAN1]

Here is the idea:

http://space.newscientist.com/data/images/ns/cms/dn12761/dn12761-1_587.jpg


Are mirrors the best way to deflect asteroids?


22:42 09 October 2007
NewScientist.com news service
David Shiga
Focusing sunlight onto an asteroid with space-based mirrors is the best way to deflect Earth-bound space rocks, a new study finds. The mirrors beat out nuclear blasts and "gravity tractors" in the study, which compared nine different deflection methods.

Asteroids larger than 5 kilometres across – such as the one that killed off the dinosaurs (http://www.newscientist.com/channel/life/mg19526204.800-discovered-the-asteroid-that-killed-off-the-dinosaurs.html) – hit Earth about once every 6 million years. But smaller space rocks spanning about 140 metres strike more often, about once every 5000, and they can cause significant damage.

Now, researchers led by Massimiliano Vasile of the University of Glasgow in Scotland have compared nine of the many methods proposed to ward off such objects (http://www.newscientist.com/article/mg17823914.600-killing-an-asteroid-softly.html), including blasting them with nuclear explosions.

The team assessed the methods according to three performance criteria: the amount of change each method would make to the asteroid's orbit, the amount of warning time needed and the mass of the spacecraft needed for the mission.

The method that came out on top was a swarm of mirror-carrying spacecraft. The spacecraft would be launched from Earth to hover near the asteroid and concentrate sunlight onto a point on the asteroid's surface.

Vaporise surface

In this way, they would heat the asteroid's surface to more than 2100° C, enough to start vaporising it. As the gases spewed from the asteroid, they would create a small thrust in the opposite direction, altering the asteroid's orbit.

The scientists found that 10 of these spacecraft, each bearing a 20-metre-wide inflatable mirror, could deflect a 150-metre asteroid in about six months. With 100 spacecraft, it would take just a few days, once the spacecraft are in position.

To deflect a 20-kilometre asteroid, about the size of the one that wiped out the dinosaurs, it would take the combined work of 5000 mirror spacecraft focusing sunlight on the asteroid for three or more years.

Vasile admits that launching and controlling 5000 spacecraft is a daunting prospect. "I must say honestly that 5000 is really a lot," he told New Scientist. But he says launching a few dozen spacecraft to deflect a smaller asteroid is within our capabilities, pointing out that this many spacecraft were launched to create the Global Positioning System (http://technology.newscientist.com/channel/tech/dn12278-gpsgalileo-pact-will-create-more-accurate-satnav.html).

The mirrors came out ahead of the so-called gravity tractor (http://space.newscientist.com/article/dn8291--gravity-tractor-to-deflect-earthbound-asteroids.html) option, in which a spacecraft simply flies alongside an asteroid and nudges it off course using the tiny force of the spacecraft's own gravity.

More time

"The problem with the gravity tractor is that essentially what you have is a low-thrust spacecraft that is pulling the asteroid," Vasile says. "The gravity tug, for the same mass into space, requires more time" and moves the asteroid by a smaller amount.

The nuclear explosion option fared about as well as the mirrors in the rankings. But the team says it is less desirable for other reasons, such as the possibility that it would break up the asteroid into fragments that could still hit Earth.

But Clark Chapman of the Southwest Research Institute in Boulder, Colorado, US, says ranking the options based on what gives the largest nudge and takes the least time is wrongheaded.

The most likely type of asteroid humans will have to deal with is in the 50- to 100-metre size range. Chapman says such space rocks require relatively little effort to move, and he argues that searches for near-Earth objects (NEOs) will probably find them long before they may strike Earth.

'Controllable and safe'

The proper way to go about ranking this "is to give weight to adequate means to divert an NEO of the most likely sizes we expect to encounter, and to do so in a controllable and safe manner", Chapman told New Scientist.

The best approach may be to ram the asteroid with a spacecraft (http://space.newscientist.com/article/dn8059-targets-for-asteroidnudging-mission-chosen.html) to provide most of the change needed, then follow up with a gravity tractor to make any small adjustments needed, he says.

"Ramming a spacecraft in an asteroid has still to be considered the reference solution for its simplicity, though the consequence of an impact are less predictable and controllable than the mirrors," says Vasile. "If I can do the same job with a smaller launch cost and with a lot of time flexibility, why should I go for something else? The mirror idea can be scaled down and up as we want...it is controllable and safe and technologically feasible."

Dan Durda, also of the Southwest Research Institute, agrees that the mirror idea should not be ruled out prematurely. "I think we need to have a lot of tools in the toolbox and the mirrors options have a place at the table of options to be considered," he told New Scientist.

High-speed collision

This is not the first time scientists have proposed using mirrors to deflect an asteroid. In 1993, Jay Melosh of the University of Arizona in Tucson, US, proposed using one very large mirror (http://www.newscientist.com/article/mg14018990.900-giant-mirror-would-see-off-doomsday-asteriod-.html) deployed by a single spacecraft for this purpose.

Vasile's team presented their findings recently at the Jodrell Bank Observatory in Macclesfield, UK, as part of celebrations for the 50th anniversary of the launch of Sputnik (http://space.newscientist.com/channel/space-tech/sputnik-legacy).

The other options considered in the study include:
• Kinetic impactor: Ramming the asteroid at high speed with a spacecraft
• Mass driver: Digging up (http://space.newscientist.com/article/mg19526166.600-drill-into-asteroids-to-stop-them-hitting-earth.html) and spewing pieces of the asteroid into space, pushing the asteroid in the opposite direction
• Propulsion: Pushing the asteroid using a thruster attached to the surface (high-thrust and low-thrust versions)
• Yarkovsky effect: Painting the asteroid to enhance the Yarkovsky effect (http://space.newscientist.com/article/dn11328-sunshine-puts-asteroids-in-a-spin.html), in which the asteroid's uneven heat radiation preferentially pushes it in a particular direction

[Frame57]

How about like putting a really big net over the earth and just catch the thing, sort of like a badmitten net.

[August]

Well i'm convinced. One question though, if these mirrored gizmos can work by super heating a particular part of a medium/small asteroid then why couldn't a specially adapted nuke touched off on or just below the surface do the same thing?

[Task Force]

How about like putting a really big net over the earth and just catch the thing, sort of like a badmitten net.
That would be a big net... Couldnt they use some kind of thing that makes a gravitational feild that goes somewhere around the asteroid and pull it.
Want to see something worse than a astroid. http://www.youtube.com/watch?v=yH16w9md6DA&fmt=18
And here is what nasa sends to save the world.
http://www.youtube.com/watch?v=WTjnI8XKk8k

[SUBMAN1]

Well i'm convinced. One question though, if these mirrored gizmos can work by super heating a particular part of a medium/small asteroid then why couldn't a specially adapted nuke touched off on or just below the surface do the same thing?
Did you read my anaology about a bullet through a paper target? Nukes work, but only on 'hard' targets. Soft asteroids have an issue. I quote the article above:

The nuclear explosion option fared about as well as the mirrors in the rankings. But the team says it is less desirable for other reasons, such as the possibility that it would break up the asteroid into fragments that could still hit Earth.

With the mirror approach, you are using the body of the asteroid against itself. Nukes = bad plan on soft material!

-S

PS. There is a problem with the mirror idea too - a rotating asteroid may negate any benefit. Of course, the heavy side usually always points towards gravity.

[UnderseaLcpl]

I agree with subman's support of the "mirror" method but I seriously doubt we would have enough advance warning to build and deploy such devices in time.

Subman already pointed out my other problem with mirrors; rotation of the target body.

It may be our best chance but I would still give us an 80% chance of being obliterated anyway.

[Task Force]

To be honest. I thik some of you all know more than some of the scientests.:rotfl:

[SUBMAN1]

I agree with subman's support of the "mirror" method but I seriously doubt we would have enough advance warning to build and deploy such devices in time.

Subman already pointed out my other problem with mirrors; rotation of the target body.

It may be our best chance but I would still give us an 80% chance of being obliterated anyway.Trying to build some defense is better than non at all in my opinion. It is only a matter of time! :yep:

-S

[Zachstar]

That I agree with. We need more and better research so that we don't have knee jerk reactions when something does come our way.

NASA is indeed a mess beyond belief. The Ares program has been little more than people trying to make a nearly dead dog try to do new tricks without dropping dead. With outright lies about a better open source idea "Direct" in my view.

[Herr_Pete]

after reading this thread, i searched the net for something i read earlier this year which may well work. a nuke may not be strong enough but a Helium 3 Bomb may well work. Alot more powerfull than a nuke. Sad bit is you have to mine it on the moon:huh:

[SUBMAN1]

after reading this thread, i searched the net for something i read earlier this year which may well work. a nuke may not be strong enough but a Helium 3 Bomb may well work. Alot more powerfull than a nuke. Sad bit is you have to mine it on the moon:huh:Anti-matter will make that that thing and a nuke look like childs play. CERN should provide some decent data soon on that.

-S

[UnderseaLcpl]

Trying to build some defense is better than non at all in my opinion. It is only a matter of time! :yep:

-S

Tell you what, you go to congress and convince them to devote funds to building asteroid-annihilating mirrors and I'll go try to convince them to blow that same money on some generic, failure-prone social program or perhaps a huge foreign aid package to a country they have never heard of where it will be stolen by warlords and corrupt officials before it ever reaches the people. Whoever convinces them wins.


Too late I already won:rotfl:


Sadly, we will probably have to suffer a significant asteroid impact or come very,very close to one before they ever do anything about it.

[Zachstar]

If the Mirror Idea is refined I think it could be possible to convince them.

3-5 billion or so spent to move a 100 year often asteroid is very worth it and 10-50 billion to move a dinosaur killer roid is well worth it as well.

Just tell them afterwards we will spend some on a social program :P

[Blacklight]

The catch to any plan to deflect an asteriod or comet is detection. If that thing is coming straight at us, due to the enormous speed the thing will be traveling as it falls toward the sun, there is a VERY limited window where we can even think of being able to do anything.
I think I recal that the danger zone is around or just inside the orbit of Jupiter. If it's closer than that, deflecting it would be near impossible considering how long it would take to get a mission together to move it, and the enormous speed the thing is traveling as it falls toard the sun.

We really only stand a chance to move the thing if we intercept it WAY out there years before it comes in at us.

[Letum]

The catch to any plan to deflect an asteriod or comet is detection. If that thing is coming straight at us, due to the enormous speed the thing will be traveling as it falls toward the sun, there is a VERY limited window where we can even think of being able to do anything.
I think I recal that the danger zone is around or just inside the orbit of Jupiter. If it's closer than that, deflecting it would be near impossible considering how long it would take to get a mission together to move it, and the enormous speed the thing is traveling as it falls toard the sun.

We really only stand a chance to move the thing if we intercept it WAY out there years before it comes in at us.

Yup, and even then there isn't a good enough way to track its heading and
velocity to calculate if it will hit us from so far out.

[Jimbuna]

Would a radar tracking station on Mars give sufficient warning ? :hmm:

[UnderseaLcpl]

Would a radar tracking station on Mars give sufficient warning ? :hmm:

Dubious. Mars is on an orbit too. It may be farther away from the object than earth is.


edit-wait, was that a joke or reference?

[Jimbuna]

Would a radar tracking station on Mars give sufficient warning ? :hmm:

Dubious. Mars is on an orbit too. It may be farther away from the object than earth is.


edit-wait, was that a joke or reference?

A bit of both actually. :lol:

[SUBMAN1]

Trying to build some defense is better than non at all in my opinion. It is only a matter of time! :yep:

-S
Tell you what, you go to congress and convince them to devote funds to building asteroid-annihilating mirrors and I'll go try to convince them to blow that same money on some generic, failure-prone social program or perhaps a huge foreign aid package to a country they have never heard of where it will be stolen by warlords and corrupt officials before it ever reaches the people. Whoever convinces them wins.


Too late I already won:rotfl:


Sadly, we will probably have to suffer a significant asteroid impact or come very,very close to one before they ever do anything about it.I bet I have a chance! Congress is so screwed up at this point, they can't even vote properly on a social program properly right now, yet might pass something weird like this much to everyones surprise! :D

-S

[August]

Did you read my anaology about a bullet through a paper target?

I did read it, but a nuke isn't a solid projectile Subman, it's an explosive, detonated on contact or just before contact. A better analogy would be a firecracker.

[SUBMAN1]

Did you read my anaology about a bullet through a paper target?
I did read it, but a nuke isn't a solid projectile Subman, it's an explosive, detonated on contact or just before contact. A better analogy would be a firecracker.The point being is energy transfer. There is no energy transfer into a non solid object. You simply break it apart and in continues on as normal as even refrenced by both the Astronaut and the article above and in every simulation done on a non solid asteroid.

Put your firecracker near your piece of paper and you will put a hole in it, but you won't send it flying!

-S

[August]

Did you read my anaology about a bullet through a paper target?
I did read it, but a nuke isn't a solid projectile Subman, it's an explosive, detonated on contact or just before contact. A better analogy would be a firecracker.The point being is energy transfer. There is no energy transfer into a non solid object. You simply break it apart and in continues on as normal as even refrenced by both the Astronaut and the article above and in every simulation done on a non solid asteroid.

Put your firecracker near your piece of paper and you will put a hole in it, but you won't send it flying!

-S

I'd say that depends on the size of the firecracker more than anything else. Besides, who ever said they would only shoot ONE nuke? How about 50? 500?

[SUBMAN1]

I'd say that depends on the size of the firecracker more than anything else. Besides, who ever said they would only shoot ONE nuke? How about 50? 500?Who knows. Create ever smaller rocks to hit the Earth. Probably not a good plan.

But since I don't do the data modeling myself, a better person to argue with would probably be the scientists themselves. They are the nuke engineers that study the blast damage for a living.

-S

[ASWnut101]

What are you talking about? The solar mirrors have been developed. It is called thin foil....

With a small amount of weight you can make an area the size of a football field.


:) I was thinking of something totally different that what Subman posted below.