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

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

http://www.theinquirer.net/gb/inquir...-idea-stopping

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

was it Armageddon?

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

-S

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

Deep Impact?

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

It was shot as a news release type.

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

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

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/wikipedi...stcurves_1.png

http://upload.wikimedia.org/math/7/2...0153064cb4.png

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.

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

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

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.


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.



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).


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.


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.