Space Colony Warfare

[Commander 598]

As a last resort, a colony could threaten to crash itself into a major city, couldn't it? Even if it breaks up in reentry, it's still going to cause low-level damage over a widespread area, and if it remains intact, I'd think there could be repurcussions similar to a medium asteroid strike or large nuclear weapon. In fact, the colony could program this as a contingency to the computers governing the guidance systems: if certain people enter the code, or the vital life support systems on the station shut down, then maneuver the station into this particular decaying orbit, which terminates on ... Beijing, or New York, or Moscow.

The Operation British colony from Gundam did break up.

However, an unexpected event occurred. Although the colony had been reinforced for the operation, it had been weakened by the fighting during its four-day journey to Earth. After entering the atmosphere at a speed of about 11 kilometers per second, the nearly ten-billion-ton colony collapsed over Arabia.

The colony's front section, which retained its original shape, impacted directly on Sydney, Australia and pierced the ten-kilometer-thick crust. As a result, it triggered the activity of the Pacific Rim volcanic belt and completely reshaped the eastern Australian continent.

The remaining fragments crossed the Pacific Ocean and fell across the northern hemisphere, chiefly on North America, and inflicted widespread casualties on civilians and Federation Forces soldiers alike.

Moreover, the shockwaves produced during the colony's passage through the atmosphere and at the moment of impact led to storms and tsunamis which raged across the whole world. These continued for more than a week, and resulted in the destruction of the Federation Forces' naval fleets. The decline of the Federation Forces' naval power was a major reason why the Zeon forces formed Jukon-class submarine fleets when they later expanded their zone of control to the surface of the Earth.

These were the modest results of the Zeon forces' greatest gamble, in which they ended up squandering so much of their extensive fighting strength. What remained after the completion of the operation were the climate disruptions and meteor showers that continued for several years afterward, as well as the vast quantities of fine particles scattered in the upper atmosphere which produced beautiful sunsets.

Note: As a result of the colony impact, the Earth's rotation was accelerated by 1.2 seconds for every hour.


Damage conditions in Australia

The kinetic energy of the colony that fell on Sydney triggered volcanic activity. Due to the resulting outflow of lava and crustal movements, the shape of Australia's eastern coast was dramatically altered. The earthquakes produced at this time were on a scale far surpassing that of the earthquakes caused by normal crustal energy, and had a magnitude of 9.5.

The area around Sydney was utterly destroyed by the falling fragments that accompanied the colony. As the colony fell, the land it passed over was also buffeted fiercely by powerful shockwaves. These combined with the shockwaves produced at the descent point to form compound waves, destroying houses across a third of Australia's land, and window glass was shattered throughout half of Australia.


The colony's descent path

The colony entered the atmosphere at a shallow angle, at an altitude of more than a hundred kilometers over Africa. It continued its flight while undergoing about three gees of deceleration due to the atmosphere, and was scheduled to fall on Jaburo about 40 minutes later. However, its flight went smoothly only for the first few minutes after atmospheric entry.

As it passed over Arabia, the colony collapsed. The front section veered south and fell onto Sydney, Australia. All three of the rear section's land panels veered north, with two falling onto North America and one in the Pacific Ocean. The remaining mirror fragments fell across the surface of the Earth.

List of damage due to the colony drop
The total energy released due to the colony drop was equal to 60,000 megatons of TNT (3 million times that of the Hiroshima explosion).

About one third of the Australian continent and one quarter of the North American continent were annihilated.

More than 320 million people were killed, injured, or missing as a result of the first wave of damage.

Climate changes and other secondary damage led to more than 2 billion killed, injured, and missing (estimated).

Earth's rotation speed was accelerated by 1.2 seconds for every hour.

The colony was an Island 3, which if I remember correctly was about 32km in length. As you can see, it was still a sufficient WMD even if it did fall short of South America. Supposing those damages are realistically accurate, i'd say any offensive action from the Earth would have serious repurcussions.

[Surlethe]

What's the source for that? And, to be frank, why should I consider the effects to be realistic because they were in an anime?

[MKSheppard]

One of the biggest Sacred Cows of Science Fiction is the story of the Brave Libertarian Miners/Colonists/Asteroid Miners rising against the Evil Corporate-controlled and run government of Earth (TM) story

I mean, how are a bunch of miners in the middle of nowhere going to somehow assert their independence against a nation state which has huge national resources to throw at them?

Harsh environment colonies like space, moon, or whatnot simply can't counter a earth based retalitation because all the earth based forces have to do is poke holes in their habitats and wait while it's like "Oh, you dropped a rock on earth? How quaint"

So the rebels can fire slugs of rock at earth with massdrivers, that's about all they can do. You think that's really going to stop the governments of earth from squishing them, since the earth can sustain far more damage than the fragile moon colonies.

Also, the established national powers have far more production capability than moon-based or asteroid-based colonies simply because of their larger GDPs.

On places with a human-habitable environment, it's different. You can have a guerilla insurgency over several years there which eventually results in independence.

The key difference is this: It's kind of hard to lead a Maoist guerilla campaign when you have to generate your own food, water, heat, and oxygen on a moon/planet/asteroid with no atmosphere or a place with a very harsh environment. It's far far easier to hide and have a guerilla movement on a planet that is earth-like, e.g Temperate.

[RedImperator]

Asteroid colonists are going to be in a much better defensive position than habitat colonists because they can actually cause real damage to Earth. All they need to do is point their mass drivers in the opposite direction and use some of the asteroid's mass as propellant for a mass extinction event. Also, unlike hab colonists, they're a long way from Earth. Any attack force is months away from the asteroid belt unless we're dealing with some pretty absurd accelerations, giving the locals plenty of warning they're coming. And there's room for them to spread out. If you had something like a loose confederacy in, say the Trojan asteroids, they could spread out into hundreds of asteroids and make themselves a diffuse target even if Earth could wipe out any individual asteroid colony.

[Commander 598]

What's the source for that? And, to be frank, why should I consider the effects to be realistic because they were in an anime?

http://www.ultimatemark.com/gundam/arch ... ntury.html
http://www.dyarstraights.com/msgundam/opentype.html

I'm not sure if it was ever animated either. UC Gundam usually manages to stay within the laws of reality.

Also of note, it appears the average Island 3 can produce it's own food.

Also, if a civilization can send billions of it's people to orbital colonies, wouldn't they be able to figure out a simple patch for holes? In UC Gundam you might occasionally see some gum like substance that seems to automatically expand over holes. That doesn't sound too far fetched.

[MKSheppard]

All they need to do is point their mass drivers in the opposite direction and use some of the asteroid's mass as propellant for a mass extinction event.

And the Earth based forces won't detect the asteroid coming for them? Even with mass drivers that's a lot of mass to move, which means it will very slowly change course; and there will be plenty of time for Earth to mess up the asteroid colony big time.

[Ar-Adunakhor]

Well, you could envision a scenario of an Earth which is desperately overpopulated and most of the arable land on the planet has either become desert, or sits unde ice-sheets, owing to climate change. An Earth in this scenario may well need to import some food to make up for what it can't produce on its own. Though an Earth in this sort of future would also be exporting people as fast as it can find places for them, and the conditions on Earth would make it so the population of the planet would be in the process of crashing.

I still don't see how that would change the fact you could do the exact same thing on Earth. Overcrowded? Stack 'em tall and bury 'em deep. Drain an ocean or two, while you are at it, and set sentries all around to keep people from overrunning the place while you build your huge biodome to grow the food in.

Seriously, why a space station? We have several miles of atmosphere to expand into and several miles of crust to bore under. Think Coruscant. In addition, there must be some room left on Earth; due to the fact you have to mine the metals and produce the parts to build that station with in the first place.

And besides you're bringing the food to Earth, which means your main cost is ensuring it survives the trip from the top of Earth's gravity well (I don't know where the hell you're getting this need to fling the food out of a gravity well.)

Woah woah woah, step back there. I said you would need to chuck the materials to grow that food up there, not the food itself. Unless you somehow know of a way we can build advanced space stations with no parts being pre-assembled in factories, no tools but those naturally occuring in space, and no planetside construction facilities....

However, to satisfy the caloric needs (2000 calories) of every person (well, six billion people) on Earth for a day requires efficiently dropping two million metric tons of food on the planet. To feed the richest 1% of that population would take 20,000 metric tons per day. That might make such a scenario more viable, where those bankrolling the colonization are expecting some sort of kickback or tax to dissuade them from sending the Marines (a sort of protection racket, if you will.)

That's a lot of food. Do tell, how is this food going to be produced? Because if it uses anything short of UBERWANK collection of solar energy and direct conversion of energy into food substances, Earth will be needing to ship up two million metric tons of minerals per day to replace the amount lost growing this food. And if they can gather and ship two fucking million metric tons of raw resources per day into an Earth orbit, why the hell do they need space stations to grow the food? Build a damn floating city or massive Antarctic BioDome, or something.

[RedImperator]

All they need to do is point their mass drivers in the opposite direction and use some of the asteroid's mass as propellant for a mass extinction event.

And the Earth based forces won't detect the asteroid coming for them? Even with mass drivers that's a lot of mass to move, which means it will very slowly change course; and there will be plenty of time for Earth to mess up the asteroid colony big time.

That's assuming they DO spot it. There are millions of asteroids in the main belts and more in the Trojans, and that's not counting all the miscellaneous ones floating around the inner system, including the Earth-crossers, and the majority of them are carbonaceous asteroids which are very difficult to spot. Earth can't possibly be tracking all of them at the same time, which means you have to hope you catch it coming in. And they don't need to be big; the K-T event was caused by a rock about the size of Manhattan Island.

Besides, who says the rock rats only have to send one? Launch a dozen or a hundred or a thousand. Only one has to get through to completely fuck everything up on the ground.

[skotos]

I thought that was the case for the three points in line with both the Earth and the Sun, but I thought that the two points 60 degrees off from Earth's orbit (L4 and L5?) were actually in gravitational "pits" (I don't know the correct term) and would be brought back into place through gravitaional effects after all but the largest peturbations?

That may be so. I'm only familiar in passing with the ones in line with the Earth and the Sun, so I don't know about the others. I would think from general principle, though, that you only get pits where you have mass, and so they wouldn't be considered "pits".

Allow me to present: a description of the Lagrange points It also includes a PDF showing the derivation.

There are some more unglamorous and unexciting possibilities.

[1] Perhaps there are no warships, but colonies are constantly trying to hack into each others control computers. Much like the new Battlestar Galactica.

[2] In Samuel R. Delany's TRITON, colonies at war do not use warships. They sent highly trained saboteurs to infiltrate. Colony support systems like life support and nuclear power plants are very vulnerable to sabotage and can cause widespread loss of life or drastic decreases in the population's will-to-fight.

[3] Perhaps warfare is conducted by infiltrating highly trained assassins to sanction with extreme prejudice an enemy colony's leaders, top research scientists, and chief engineers.

The three of these together sounds like a pretty damn good story, actually.

If you think that those three together sound like a pretty damn good story, then I recommend Schismatrix, by Bruce Sterling. In Schismatrix Earth has reverted to a low technology level, and so all advanced humans live in space. As a result, destruction of a habitat or even a ship is considered taboo - it's the equivalent of using a nuke on a city in the modern world. Wars are conducted via a combination of assassins, sabotage, and industrial espionage.

It's no grandiose war novel though, most of the book is seen through the eyes of one character, whose main interest is to survive. You mostly get bits and pieces of warfare through his experiences, but his experiences are colorful enough to give you an idea of how warfare in the Schismatrix works.

[Patrick Degan]

Seriously, why a space station? We have several miles of atmosphere to expand into and several miles of crust to bore under. Think Coruscant. In addition, there must be some room left on Earth; due to the fact you have to mine the metals and produce the parts to build that station with in the first place.

Evolutionary safeguard, for one reason. Even if we discount the possibility of a large-mass asteroid strike resuling in an ELE, Earth's biosphere is not going to remain viable forever.

[Zor]

I still don't see how that would change the fact you could do the exact same thing on Earth. Overcrowded? Stack 'em tall and bury 'em deep. Drain an ocean or two, while you are at it, and set sentries all around to keep people from overrunning the place while you build your huge biodome to grow the food in.

Seriously, why a space station? We have several miles of atmosphere to expand into and several miles of crust to bore under. Think Coruscant. In addition, there must be some room left on Earth; due to the fact you have to mine the metals and produce the parts to build that station with in the first place.

A-Once the First Station is built, the Second one gets a hell of a Lot easier to build
B-Construction in Largescale Objects is easier when you don't have to use Cranes or things like that, simply floating componets into position and welding them.
C-There is plenty of minerals in the Solar System, more than enough to build plenty of O'neill Cylinders and the Fact that an O'neill Cylinder's Industrial Facilities are located well away. This includes water and Air.

Woah woah woah, step back there. I said you would need to chuck the materials to grow that food up there, not the food itself. Unless you somehow know of a way we can build advanced space stations with no parts being pre-assembled in factories, no tools but those naturally occuring in space, and no planetside construction facilities....

Basicly your assuming that in Space Colony Construction will be completly dependant on Earthbased Factories, which would only hold true for the First colony or two (which does not need to be a full flegded O'neill Cylinder, a smaller station like a Stanford torus would be acceptable).

A single Open Type O'neill Cylinder has over a hundred square kilometers of ideal realestate inside it with acesss to large amounts of cheep solar Power, there are plenty of people, especially well off people who would want to move to said colonies. This is before there manufaturing (without enviromental damage inflicted by earth based facillities) and agricultural capacities (Crops like Predictable weather, constant growing season and a lack of night without the costs of a Biosphere).

Zor

[Pablo Sanchez]

There's a few problems with throwing rocks at the Earth--

It's an obvious tactic, and being involved in a war with the space colonies will cause the Earth-nation to put a great deal of resources into tracking objects. With future technology of the sort we're talking about and the resources of the entire planet it wouldn't be unfeasible to get full coverage of the sky. Even then, the job is simplified by the fact that Earth doesn't have to track every asteroid, it only has to look for acceleration and phenomena related to it. Accelerating an ELE-level object is going to put out a lot of light and heat, and that is the first thing the Earth will be looking at.

Then, once the projectile is detected, inertia is working against the pitcher. Assuming that the colonists have the technology to accelerate the projectile to a given speed, it's a fair assumption that the Earth has similar technology--i.e., given the same amount of time, they have the technology to exert equal force on the projectile and stop it in it's tracks. Of course, one big difference is that the colonists have to accelerate the object from a "stop" relative to the Earth, whereas the defending Earth forces just have to nudge it, thus expending far less energy (depending on how far out the object is spotted, adjusting it's direction by a fraction of a degree would cause it to miss by a generous margin). And moreover, the Earth has far more resources than the colonies for this kind of work. It's a losing game for them.

[Winston Blake]

Of course, one big difference is that the colonists have to accelerate the object from a "stop" relative to the Earth, whereas the defending Earth forces just have to nudge it, thus expending far less energy (depending on how far out the object is spotted, adjusting it's direction by a fraction of a degree would cause it to miss by a generous margin).

Actually AFAIK most asteroids naturally have very different orbital velocities relative to Earth, and it would only take a nudge to make their orbits a little bit eccentric and intersect with Earth's.

[Pablo Sanchez]

Actually AFAIK most asteroids naturally have very different orbital velocities relative to Earth, and it would only take a nudge to make their orbits a little bit eccentric and intersect with Earth's.

This is undoubtedly true, but do you want the asteroid to impact on your schedule or on it's own schedule? If you just nudge the asteroid so that it's orbit intersects the Earth at some point in the future, it could take years to see any effect--in the meantime you've lost the war.

[RedImperator]

Actually AFAIK most asteroids naturally have very different orbital velocities relative to Earth, and it would only take a nudge to make their orbits a little bit eccentric and intersect with Earth's.

This is undoubtedly true, but do you want the asteroid to impact on your schedule or on it's own schedule? If you just nudge the asteroid so that it's orbit intersects the Earth at some point in the future, it could take years to see any effect--in the meantime you've lost the war.

It's not a viable short term tactic unless you're lucky enough to be able to sneak an engine aboard an Earth-crosser that's close to Earth already, and I think we can pretty safely assume those will be watched very closely. I see two strategic roles for rock-dropping: as a sneak attack to erase Earth's advantages in one stroke, and a MAD deterrent. The belters can threaten to nudge hundreds of asteroids if they're attacked. Even if Earth can deflect them all, that's years of hassle, and if one K-T sized object gets through, Earth is fucked. It won't prevent a military defeat of the belters if Earth decides to wipe them out, but it seems to me it could deter an attack in the first place.

And as long as we're on the subject, a large asteroid is a tougher target than a space habitat or ship, and far more mobile and hard to detect than a planet, and the asteroid belt is a damn long way from Earth. If anyone off-world really stands a chance against Earth, it's the belters.

[Pablo Sanchez]

And as long as we're on the subject, a large asteroid is a tougher target than a space habitat or ship, and far more mobile and hard to detect than a planet, and the asteroid belt is a damn long way from Earth. If anyone off-world really stands a chance against Earth, it's the belters.

Just so. In Niven's Known Space series, there was a cold war in the form of an economic blockade fought between the Belters and the Earth. The Belters survived by pretty much eating nothing but space-grown fungus for years, while Earth lost access to resources from the asteroid belt. Eventually, although the Flatlanders suffered far less from the economic warfare than the Belters, they were less willing to deal with it.

[Aeolus]

Do the Earth forces have space superiority, or do the colonies maintain a space fleet of their own?

Assuming the passage to the rebel colony is unimpeded, I imagine the threat of force against these vunerable structures would be enough. Even if not I'd guess teams could be sent to take over control centers, shut down power, halt the colony's rotation and generally make life aboard absolute hell until the colonists surrender.

O'Neil Colonys are miles across and tens of miles long. How do you propose to stop the rotation? The population of 1 is easily in the millions so destroying the colony is politically tricky to say the least.

[MKSheppard]

And moreover, the Earth has far more resources than the colonies for this kind of work. It's a losing game for them.

I was going to sum up basically the same views as you pablo, but you did it far better and more eloquently than I ever could have.

[MKSheppard]

I see two strategic roles for rock-dropping: as a sneak attack to erase Earth's advantages in one stroke

Again, HOW? How will the various military forces on Earth like US SPACE COMMAND, whatever the Chinese, Russians, Indians, Japanese, whoever come up with miss a giant rock heading for earth; one that's thrusting in a completely unnatural trajectory?

and a MAD deterrent. The belters can threaten to nudge hundreds of asteroids if they're attacked. Even if Earth can deflect them all, that's years of hassle, and if one K-T sized object gets through, Earth is fucked.

That's a massive gargantugan expenditure of money, time, and energy; whereas for much less effort, Earth-based forces can just crank out nuclear devices with virtually unlimited megatonnage and plaster the belters far quicker than their asteroids could reach earth.

If anyone off-world really stands a chance against Earth, it's the belters.

Nah. If the technology exists to colonize the belt, then the technology exists to quickly deliver a crushing blow on the belters, using the Earth-based forces' massive advantage in GDP to maximum effect.

[RedImperator]

I see two strategic roles for rock-dropping: as a sneak attack to erase Earth's advantages in one stroke

Again, HOW? How will the various military forces on Earth like US SPACE COMMAND, whatever the Chinese, Russians, Indians, Japanese, whoever come up with miss a giant rock heading for earth; one that's thrusting in a completely unnatural trajectory?

It doesn't need to be giant. A six mile carbonaceous asteroid would be plenty to cause a mass extinction event and difficult to see. It doesn't have to thrust for very long. All it has to do is get nudged a little and then inertia does the rest.

and a MAD deterrent. The belters can threaten to nudge hundreds of asteroids if they're attacked. Even if Earth can deflect them all, that's years of hassle, and if one K-T sized object gets through, Earth is fucked.

That's a massive gargantugan expenditure of money, time, and energy; whereas for much less effort, Earth-based forces can just crank out nuclear devices with virtually unlimited megatonnage and plaster the belters far quicker than their asteroids could reach earth.

And how do they get them there? It's anywhere between 2 and 3 and a half AUs to the main belt, and more than 5 AUs to the Trojans. That's months of travel with most realistic propulsion systems, and the belters can see them coming the whole way, unless Earth already has patrols in place in the belt, which would preclude this tactic, but would cost a fortune to maintain.

And if the technology exists to quickly and cheaply get nuclear warheads to the asteroid belt (and lots of them, because this isn't Wing Commander and asteroids are hard targets that will require serious firepower to destroy, nuclear weapons are actually rather unsuited for the job, and the belters can see you coming from months away), then the technology also exists to quickly and cheaply nudge asteroids into Earth-impacting orbits, even if it takes them years or decades to get there.

If anyone off-world really stands a chance against Earth, it's the belters.

Nah. If the technology exists to colonize the belt, then the technology exists to quickly deliver a crushing blow on the belters, using the Earth-based forces' massive advantage in GDP to maximum effect.

How does this follow? Assuming industry exists in the belt and they're not dependent on Earth for manufactured goods (which would make colonizing the asteroids economically unfeisable anyway), it's much easier to spread from asteroid to asteroid than it is to get from Earth to the belt.

[SirNitram]

The biggest things about 'Just lob some nukes!' are...

1) It's uphill all the way. First Earth orbit, then up the Sun's gravitational field. 'Roids will be going down the whole way.

2) 'Roids, if they can be thrown at Earth, can also adjust their orbits. A bit of thrust a few months before impact means you get the hell out of the way no problem.

3) As Red noted, a 'roid is rather difficult to kill with a nuke.

[Aeolus]

All this talk about the Earth being able to blow up colonies easily or Colonys being able to drop asteroids on Earth is overkill. We have had the ability for 60 years to destroy our rivals but we don't use it. Why in any future conflict between colonies and Earth nations would they? More likely any wars would be limited.

[MKSheppard]

It doesn't have to thrust for very long. All it has to do is get nudged a little and then inertia does the rest.

And then take forever to reach it's target.

And how do they get them there? It's anywhere between 2 and 3 and a half AUs to the main belt, and more than 5 AUs to the Trojans. That's months of travel with most realistic propulsion systems, and the belters can see them coming the whole way, unless Earth already has patrols in place in the belt, which would preclude this tactic, but would cost a fortune to maintain.

You're not thinking this through. If it's 2 to 3.5 AUs between the belt and months of travel with manned ships, then what's the point of making asteroids of doom? They'll take even longer to travel from the belt to earth; by which the war will be long over.

If the technology somehow exists to make these asteroids of doom reach Earth in 1 month, then the same technology also exists to allow much lighter ships to reach the belt or the asteroids faster from earth.

And if the technology exists to quickly and cheaply get nuclear warheads to the asteroid belt (and lots of them, because this isn't Wing Commander and asteroids are hard targets that will require serious firepower to destroy, nuclear weapons are actually rather unsuited for the job, and the belters can see you coming from months away), then the technology also exists to quickly and cheaply nudge asteroids into Earth-impacting orbits, even if it takes them years or decades to get there.

You're not thinking this through clearly. It takes far far less energy to move a thermonuclear device to the asteroid belt than it takes to move a really big asteroid large enough to screw life up on earth. And you've pointed the problem out here. If it takes months for Earth to retalitate and the Belters years or decades.....well....

How does this follow?

It costs money to do things like build warships of doom, etc. The only way the asteroid belt population and GDP could ever reach significant figures is if we invented unobtanium drive technology, because they would essentially be spacegoing banana republics, entirely dependent on the sale of whatever material their asteroid is made up; and because of the gargantugan amounts of stuff available from just a single asteroid, the prices of the raw materiels will be incredibly depressed.

[Pablo Sanchez]

You're not thinking this through clearly. It takes far far less energy to move a thermonuclear device to the asteroid belt than it takes to move a really big asteroid large enough to screw life up on earth.

I think they were assuming that the the thermonuclear missile has to escape Earth's gravity well. However, if we assume space elevator technology (which is a typical starting point for out-space colonization in science fiction), it would be pretty cheap to move the materials for the weapons from Earth to orbit, then assemble them there. Finally, it isn't necessary for the missiles to altogether break the asteroid projectile into little pieces. A barrage of high-powered thermonuclear warheads would serve the purpose of destroying any guidance installations on the rock and giving it a little push off-course.

[MKSheppard]

1) It's uphill all the way. First Earth orbit, then up the Sun's gravitational field. 'Roids will be going down the whole way.

Except if asteroid belt colonization is actually feasible, then we'll have drive technology to make such a problem academic.

2) 'Roids, if they can be thrown at Earth, can also adjust their orbits. A bit of thrust a few months before impact means you get the hell out of the way no problem.

Except the orbit has to intersect earth. That means that the asteroid can't whiz around the sky willy nilly. That means you're limited in how much "Evasive manuvers" you can do.

3) As Red noted, a 'roid is rather difficult to kill with a nuke.

Link to Mike's Asteroid Calculator

Cratering energy is the energy required to blast out a crater of depth equal to the radius of the asteroid, which should easily result in its catastrophic disruption.

A 10 km wide asteroid would only need 180.9 megatons to crater it into smaller pieces which could be dealt with. Considering that the technology exists to create 100+ megaton fusion devices in the 1960s....