Space Based Weapon systems

LOL, are you still being serious? I can’t tell …

Err… obviously not… Hydrogen is a relatively light element… an object the size we are talking about (ie not even moon sized let alone the size of a planet) would not have the gravity required to keep the matter from being blown away from a detonation let alone maintain a chain reaction required to actually keep it burning. Even Jupiter doesn’t have enough Hydrogen stored under enough pressure and heat to start a chain reaction when hit by the Shoemaker Levy comet. The heat generated by the impact would have been enormous but still not sufficient to start a fusion reaction.

LOL, are you still being serious? I can’t tell …

Sad thing is he probably isn’t :diablo: Needless to say you can’t ignite a star like touching a match to gasoline.

And if it explodes on impact and we find out the object was made entirely of Slush Hydrogen… a star is born…

LOL, are you still being serious? I can’t tell …

This isn’t a process whch would be effective over a short distance, you’d need to rendesvous with the inbound something like ten-twenty years out (in flight time to impact).

Firing nukes at a rock as it is passing the moon like in the movie Armageddon would be completely pointless…
A mass thrower would offer precise and measured trajectory change that would make more sense at any range that a nuke would be worth while.

So? There is no limit to the potential yield of a thermonuclear weapon, you just have to build the thing.

You also have to get it into space and launch it on an intercepting course. The bigger and heavier that warhead is the more likely it is not work when impacting a target at 20+km/s. Equally the bigger and heavier it is the more fuel will be needed to accelerate and manouver the warhead to intercept the target.

That’s why I think a massive, gigaton-class nuclear device is the most sensible option. You can vaporize the target without fear of screwing up.

And if it explodes on impact and we find out the object was made entirely of Slush Hydrogen… a star is born… still hurtling towards earth…

When we can make such a thing we can start talking. Till then a mass thrower makes much more sense to me… even if it isn’t as exciting…

Actually one idea I’ve seen proposed is, amusingly enough, to place a rocket motor on a small asteroid and use that to alter the trajectory of the inbound.

A solar power ion engine would have a lot of merit but if the object is spinning it would have to be pulsed to just push in one direction. A liquid or solid fuelled rocket would be pointless… imagine placing a Saturn IV rocket pointing downwards to push the earth out of orbit. Either rocket technology would need enormous leaps to greatly increase the exhaust velocity to near that of the speed of light (ie Ion) or you’d need the fuel supply for the rocket to be a significant fraction of the weight of the object being pushed.

Edit: actually a nuclear powered ION engine would be more reliable…

You actually aren’t trying to vaporize the asteroid. That would take an incredibly large nuke.

So? There is no limit to the potential yield of a thermonuclear weapon, you just have to build the thing.

All you’re trying to do is get a big enough warhead deep enough and use the ejected material as your reaction mass. Think Castle Bravo for a vernier to adjust the trajectory.

Yeah but the problem with that idea is twofold: 1) you have to actually hit the asteroid, requiring great accuracy, and have some way of burying but not damaging the nuke, and 2) once you impact and bury, you’re HOPING that the detonation energy functions like a vernier. The asteroid could fracture instead, and could potentially comprise parts large enough to still be a major threat (over 1km). Plus, you might actually give such a part a boost and increase its velocity but not change the trajectory.

That’s why I think a massive, gigaton-class nuclear device is the most sensible option. You can vaporize the target without fear of screwing up.

But the problem is you are talking about using a rock to divert the course of a car… or the mass of a Granit to divert the course of a supertanker…

Actually one idea I’ve seen proposed is, amusingly enough, to place a rocket motor on a small asteroid and use that to alter the trajectory of the inbound.

The mass you’d need to eject would be very large and you would need precise control of its direction to ensure the reaction force of the recoil diverted the object the right way… otherwise you could just accelerate it or decellerate it slightly.

This isn’t a process whch would be effective over a short distance, you’d need to rendesvous with the inbound something like ten-twenty years out (in flight time to impact). Fortunately, with a lot of the current programs available to track and ID asteroids, this isn’t entirely out of the question.

For more info on some of these ideas, check this out:

http://csat.au.af.mil/2025/volume3/vol3ch16.pdf

When heated to the temperature of a star Iron will melt but being a good conductor the heat energy will be spread over the entire mass which might rise in temperature a few degrees overall.

Remember it is the conductivity of Iron that “Kills Stars”. The Iron conducts heat too efficiently and kills the fusion process… when the core of a start contains too much iron its core stops burning and the outer shell collapses in onto it. The resulting energy burst is called a nova for a smaller star… for a larger more massive star the explosion is much greater and called a supernova. The latter able to create neutron stars and even singularities (black holes). It is the novas that create the heavier elements like uranium and titanium as the iron cores are crushed by the collapsing outer shells… imagine a lump of Uranium 20km across floating through space… or for that matter a black hole with the mass of earth… it would be about 2-3 cm across and completely unstoppable.

Thing is you’re not trying to blow it apart but to change it’s trajectory

Quite true, but the earth is a large gravity well. You will have to change its trajectory very early to actually save Earth this time… and of course the change in trajectory would have to be extrapolated out to see whether it is a stable change, whether it will now hit something much later on or whether it will leave the solar system never to return.

meaning you could come at it from the side and dictate precisly how fast you impact.

Using impact alone is not enough. If we are to not be pi$$ing in the wind we need to hit the object while it is a long way away from us. This means more fuel and less payload in whatever actually hits the target and because the fuel will be burnt on the way that means light impactor. Just like a bullet will not throw a human back when it hits, the enormous mass of the target will absorb the impact of such an object with only a very very minor effect… no matter how hard it hits.

An iron asteroid is probably the BEST case when it comes to trying to move it because it’s less likely to fragment when the nuke goes off and it’s much easier to transfer momentum to the entire mass.

When heated to the temperature of a star Iron will melt but being a good conductor the heat energy will be spread over the entire mass which might rise in temperature a few degrees overall.
Without knowing the internal structure we would have no idea how it would react to a large internal explosion. If it was close enough to be “scanned” then it is probably too close for us to do anything meaningful to stop it.

Don’t think of this object as being a ball… the vast majority seem to be very irregular shapes.

Obviously if you’re just hoping to break it into small enough pieces that they all burn up then you don’t want iron.

The power required to convert it to gravel would be equivelent to the power required to stop it dead in its tracks…

[quote]Because you really have no way of knowing exactly how much you’re going to be able to nudge it until the bomb has gone off and you measure it’s new velocity you’d probably want to send several out at a couple hours interval.
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Herein lies the problem. You detonate your first nuke and take some time to track the effect. The second weapon would have to be in space already on its way or the object will get too close to earth for another shot to be worth while. The second nuke would have to have full manouvering capability and a dialable threshold. Now that you have blown a large chunk off the object you will have to take several measurements to determine its new course. Your first strike will likely have changed everything… from rate of spin to internal structure, so you need to calculate where to hit with the next warhead, or even if the second warhead is necessary. Not an easy task. And that is assumeing the first explsoion has made things better rather than worse. If it split a long asteroid into two large parts then you are going to have to split your inflight warhead in two. Two large impacts will do more damage than one enormous one…

All you’re trying to do is get a big enough warhead deep enough and use the ejected material as your reaction mass.

I am suggesting that rather than use a nuclear weapon as a dumb Vernier rocket thruster, that you have a simple mass thrower that you land on the object and use a more precise method of diverting its course… either to a safe stable orbit or to a collision with Jupiter or the Sun to permanently remove the threat.

1-2 seconds? Where do you get that from? And please don’t quote the speed of impact, the faster the gravel enters the atmosphere, the more likely it will shatter and break up further.

First of all most of those pretty meteor showers we see at certain times of the year are material the size of grains of sand. Objects the size of cricket balls usually hit the ground and are not burnt up in the atmosphere. Second 1-2 seconds comes from the fact that at 60km/s that is how long they take to travel through our atmosphere. Why would it shatter? Comets break up and explode at altitudes of 10km or so because they are made of ice. when I say Gravel I don’t mean the fine gravel you put on your driveway… I am talking about bits of rock that range from the size of a city block through to the size of a grain of sand. Such a gravel result for an object a few kms across is not even possible with currently available nuclear weapons let alone a really large object like the one that killed the dinosaurs… of course unlike the dinosaurs we might even see this one coming.

That’s because it’s in the ground, the surrounding PLANET contains the explosion. An asteroid will not have such mass.

They are not detonated at the core of the planet. They are normally detonated less than a few hundred metres from the surface. There are plenty of objects in space with that much volume to absorb an explosion.

The energy will not be the same. Many asteroids are low density ice – snow in other words – meaning the mass is lower, thus the kinetic energy is lower. Snow is also more likely to disintegrate and break up on impact with the atmosphere compared to iron. Depending on the size of the asteroid, it could mean a lot to those in Earth at the time of impact.

First of all I was talking about energy release and in that instance they are the same… the Tunguska incident involved a comet that exploded at 10km above the surface so the energy released did not create a crater, nor did it blow surface material into the air, but it flattened over 2,000 square kms of forest and the “glow” was seen in London.
Second asteroids do have some external ice but if they were made entirely of ice they would be comets. The solar wind will remove most external ice deposits when they get close enough to us to be a problem.

As Charles Babbage said, I am not able to rightly apprehend the kind of confusion of ideas that could provoke such a question.

We can’t defeat bunkers on earth buried under more than a few hundred metres of granite but some here suggest we can fire a penetrator to bury itself into an object in space deep enough to be effective, hit it in the right spot with the right yield of nuclear warhead that will survive such an impact and detonate at the exact right time with the right amount of force to divert an object billions of kms from earth just enough to avoid a collision.

Sounds like an old proverb… if the only tool you have is a hammer, then treat every problem like it is a nail. Would be nice to find a sensible use for all these nuke missiles we have, but the reality is that a different solution would be better.

Given 10 years warning, a 10-100 meters per second change in velocity towards one side or another could alter the orbit well ehough to miss.

Given 10 years warning a 1 thousandth of a degree change in vector would suffice… but I’d rather have a mission to land on the damn thing and change its direction precisely than hit it with nukes and hope for the best.

AS for what the object is made of, cant humies recognise that already with satellites and other telescopes and stuff they got….

We don’t even know the structure of the Earth 100% accurately. An object from space could be a snowbal from the Oort cloud, or it could be the super dense material from a supernova for all we know.

Damn, we’re doomed ;(

There is a record going back thousands of millions of years showing mass extinctions… we can see this coming… and it is actually due.

What if like A first explosion to fragment the object and then a series of explosions timed at right moments to deflect the incomming gravels….yes, some will get through, but better to save the planet than few cities imo…

For an object the size of the one that did in the dinosaurs all the nukes ever made combined would not be enough to reduce it to gravel… unless you could position them like you were demolishing a building with billions of charges all placed in the exact right place and set to go off at the exact perfect time.

Damn, we’re doomed ;(

What if like A first explosion to fragment the object and then a series of explosions timed at right moments to deflect the incomming gravels….yes, some will get through, but better to save the planet than few cities imo…

AS for what the object is made of, cant humies recognise that already with satellites and other telescopes and stuff they got….

But the problem is you are talking about using a rock to divert the course of a car… or the mass of a Granit to divert the course of a supertanker…

The mass you’d need to eject would be very large and you would need precise control of its direction to ensure the reaction force of the recoil diverted the object the right way… otherwise you could just accelerate it or decellerate it slightly.

Given 10 years warning, a 10-100 meters per second change in velocity towards one side or another could alter the orbit well ehough to miss.

Not so much that you would notice… in the 1-2 seconds it would take for the gravel to travel through our atmosphere how much gravel would be turned into ash?

1-2 seconds? Where do you get that from? And please don’t quote the speed of impact, the faster the gravel enters the atmosphere, the more likely it will shatter and break up further.

Underground nuclear explosions rarely create gravel pits. A large Sphere is vapourised… and area outside that is turned into a type of glass, and outside that there are major cracks but the size of the weapon required to actually blow apart a very large lump of rock is enormous and far beyond what we can currently make.

That’s because it’s in the ground, the surrounding PLANET contains the explosion. An asteroid will not have such mass.

At 60km per second… no it doesn’t. The energy released will be the same… hardness has very little to do with the energy released, though it effects the depth of penetration… that will mean little to those on Earth at the time of impact..

The energy will not be the same. Many asteroids are low density ice – snow in other words – meaning the mass is lower, thus the kinetic energy is lower. Snow is also more likely to disintegrate and break up on impact with the atmosphere compared to iron. Depending on the size of the asteroid, it could mean a lot to those in Earth at the time of impact.

Something else intelligent people with knowledge of Newton’s laws of motion, the inverse square law and other basic laws of physics seem to have problems with… objects from space can be moving from 30km/s to more than 60km/s. We can’t even make bunker busters to take out deeply buried bunkers… does there exist a nuclear warhead that can survive a collision at well over 40km/s (target speed plus the speed required to leave earths orbit) and penetrate several hundred metres of an unknown material that could be iron or could be ice and detonate at exactly the right time?

As Charles Babbage said, I am not able to rightly apprehend the kind of confusion of ideas that could provoke such a question.

The kinetic penetrator might work, but not as an actual kill vehicle designed to fragment the asteroid. It is possible to hit an asteroid with an object moving quickly enough to adjust the trajectory of the asteroid. You’re gonna need some massive accuracy at range though.

Also, the idea of using a nuke isn’t to hit the target. The idea is to use a massive enough nuke, proximity detonated, that the detonation vaporizes the target. If that is for some reason technologically impractical at the present time, then the blast can still be used to alter the asteroids course.

You actually aren’t trying to vaporize the asteroid. That would take an incredibly large nuke. All you’re trying to do is get a big enough warhead deep enough and use the ejected material as your reaction mass. Think Castle Bravo for a vernier to adjust the trajectory.

But the problem is you are talking about using a rock to divert the course of a car… or the mass of a Granit to divert the course of a supertanker…

The mass you’d need to eject would be very large and you would need precise control of its direction to ensure the reaction force of the recoil diverted the object the right way… otherwise you could just accelerate it or decellerate it slightly.

Depending on the size of the nuke and how deep you were able to get it you could eject a massive amount of material. And direction would be less of a problem then the precise amount delivered. Because you really have no way of knowing exactly how much you’re going to be able to nudge it until the bomb has gone off and you measure it’s new velocity you’d probably want to send several out at a couple hours interval.

Worst case scenario… an Iron target (ie 5km diameter plus) hit by a large DU penetrator at over 60km/s and that penetrator is likely to be vapourised on impact and will have little or no useful penetration… the following nuke warhead would not do much better and would likely be vapourised before it detonates.

Thing is you’re not trying to blow it apart but to change it’s trajectory meaning you could come at it from the side and dictate precisly how fast you impact. The surface of the astroid and the DU penetrator are both going to flow but at different rates so you should still be able to get a nuke a bit beneath the surface. If you can’t go as deep as you’d like then use a bigger nuke. The idea is to bury a big enough nuke deep enough to blow away enough material (that acts as a reaction mass) to nudge it. Depending on how much lead time you had you might not need to nudge it much at all. An iron asteroid is probably the BEST case when it comes to trying to move it because it’s less likely to fragment when the nuke goes off and it’s much easier to transfer momentum to the entire mass. Obviously if you’re just hoping to break it into small enough pieces that they all burn up then you don’t want iron.

It is possible to hit an asteroid with an object moving quickly enough to adjust the trajectory of the asteroid.

But the problem is you are talking about using a rock to divert the course of a car… or the mass of a Granit to divert the course of a supertanker…

If that is for some reason technologically impractical at the present time, then the blast can still be used to alter the asteroids course.

The mass you’d need to eject would be very large and you would need precise control of its direction to ensure the reaction force of the recoil diverted the object the right way… otherwise you could just accelerate it or decellerate it slightly.

The kinetic penetrator might work, but not as an actual kill vehicle designed to fragment the asteroid. It is possible to hit an asteroid with an object moving quickly enough to adjust the trajectory of the asteroid. You’re gonna need some massive accuracy at range though.

Also, the idea of using a nuke isn’t to hit the target. The idea is to use a massive enough nuke, proximity detonated, that the detonation vaporizes the target. If that is for some reason technologically impractical at the present time, then the blast can still be used to alter the asteroids course.

It’s actually nowhere near as complicated as people think it is. Rotational period is known, relative velocities are known, and trajectories are known.

Worst case scenario… an Iron target (ie 5km diameter plus) hit by a large DU penetrator at over 60km/s and that penetrator is likely to be vapourised on impact and will have little or no useful penetration… the following nuke warhead would not do much better and would likely be vapourised before it detonates.

Would not want to be the mathmetition having to calculate exactly when the impactor would have to hit and when to time the detonation. Most asteriods spin.

It’s actually nowhere near as complicated as people think it is. Rotational period is known, relative velocities are known, and trajectories are known.

I’m telling you guys, a staged-boosted thermonuclear warhead is the way to go here. Any other system and you risk either missing, not getting the right result, or having some other problem. Take the example of the 10 mT IVY MIKE test. It created a crater 6240 feet across and 164 feet deep. Bigger warhead, larger amount of matter turned to energy, I.E. vaporized.

But, and maybe I’m looking at this wrong, wouldn’t a trillion tons of gravel burn up more in the atmosphere then a trillion ton solid rock?

Not so much that you would notice… in the 1-2 seconds it would take for the gravel to travel through our atmosphere how much gravel would be turned into ash?

but it’s effectiveness against a stoney asteroid or a comet would be orders of magnitude better than an airburst nuclear explosion.

Underground nuclear explosions rarely create gravel pits. A large Sphere is vapourised… and area outside that is turned into a type of glass, and outside that there are major cracks but the size of the weapon required to actually blow apart a very large lump of rock is enormous and far beyond what we can currently make.

Depending on it’s composition they’d either use a surface or subsurface burst with the ejected material providing the reaction mass and the blast being coupled better to the asteroid.

… a blast on the surface would just super heat the surface… and irradiate it.
A nuclear blast in space is like the solar wind. Very high velocity but also very light materials. Men doing spacewalks are not blown around by the solar wind… even though it travels at 900km/s or so.

You’re not trying to disipate it. You’re trying to change the mass’s vector.

If you are trying to divert its course then landing on it and operating a mass engine to excavate material from the surface and lob it out into space at the correct instant makes rather more sense. Remember most rocks spin and to successfully divert the course of an object by blowing material off it requires very accurate information about its structure. Hit it in the wrong place and you might just break it into two pieces that will do even more damage.

Actually what it’s composed of makes a HUGE difference on the effect of the impact.

At 60km per second… no it doesn’t. The energy released will be the same… hardness has very little to do with the energy released, though it effects the depth of penetration… that will mean little to those on Earth at the time of impact.

As long as it’s turned to gravel, the massive increase in surface area to volume ratio will mean it will burn up in the atmosphere, trillion tons or not.

The problem is of course that it will not turn the entire asteroid into gravel… any more than underground tests have turned millions of cubic metres of granite into gravel when tested. In fact the French assured most of the Pacific that underground testing was safe because there is a sphere of vapourised rock but that is contained within the rock structure…

causing a force against the direction of orbit and would slow the target, thus changing its orbit

Would not want to be the mathmetition having to calculate exactly when the impactor would have to hit and when to time the detonation. Most asteriods spin.

the first piece of kit I would add is a smaller kinetic energy penetrator that would impact the target a couple of seconds just before the main one, just to make the job of the main penetrator easier.

Again… most asteroids spin. You have the problem of wanting to hit the target as early as possible because the sooner you hit it the less you have to move it to be sucessful… but then you might not get very much warning and you need to know what it is made of before you try to hit it or you could just make things worse.

as well as allowing the warhead to survive the impact to the point of detonation,

Something else intelligent people with knowledge of Newton’s laws of motion, the inverse square law and other basic laws of physics seem to have problems with… objects from space can be moving from 30km/s to more than 60km/s. We can’t even make bunker busters to take out deeply buried bunkers… does there exist a nuclear warhead that can survive a collision at well over 40km/s (target speed plus the speed required to leave earths orbit) and penetrate several hundred metres of an unknown material that could be iron or could be ice and detonate at exactly the right time.

But, and maybe I’m looking at this wrong, wouldn’t a trillion tons of gravel burn up more in the atmosphere then a trillion ton solid rock? Having massively more surface area?

That’s something that the opponents of the Nuclear option for asteroid destruction always forget. As well as a lot more of the mass burning up, even more will be slowed down to a speed that will not cause major damage. OK, some of the bigger bits will without doubt do major damage, however this will not have the same effect as one massive lump of rock hitting the Earth at a single point.

I think any attempt at a nuclear astroid killer would have to incorperate a SERIOUS penetrator cap, make the objects energy work against it.

A SERIOUS penetrator cap would be essential, as stated the detonation of the weapon would have to inside the mass of the object to convert the maximum amount of radiation into mechanical shock. If such a device was required to be built, the first piece of kit I would add is a smaller kinetic energy penetrator that would impact the target a couple of seconds just before the main one, just to make the job of the main penetrator easier. A large lump of depleted uranium would be just what was required, as well as allowing the warhead to survive the impact to the point of detonation, the neutron radiation burst of your Fusion stages would cause a massive fast fission of the U238, the plasma of which would act as a massive tamper on your fusion stage, boosting it and massively increasing the yield. Also the big thick lump of U238 at the front would fast fission better because it would be compressed by the mass of the target, causing a force against the direction of orbit and would slow the target, thus changing its orbit (the rocket effect of the blast coming out of the hole would have the same effect, as well as the rock/iron vapours from the ferrous asteroid). Done correctly, the weapon would do the job, as the target asteroid would miss the Earth, even if you don’t break it up into a lot of smaller pieces.

Its amazing how many supposedly intelligent people forget Newton’s laws of motion, the inverse square law and other basic laws of physics.