You have never had any experience with guided munitions. Accuracy to less then a meter. Calculating the crater size is very easy to do when you know the yield, depth and shape. We have interceptors that can strike a ballistic missile 100K up.
A good friend of works in the mining industry laying out drilling holes for blasting. By varying the timing of the detonations he can move the dirt where ever he needs is. If he had to use high yield atomic weapons he reckons he could easily create a chain of craters with perfect alinement. He also pointed out that for nuclear explosions to create deep crates like those seen in the crater chains they would have to be buried deep underground, at about 2-3times the depth of the crater. Nukes release radiant energy, while conventional explosives produce energy in the form of and expanding shockwave of gas. Nukes do not produce significant craters when detonated at ground level while conventional explosives can. He also pointed out that craters produce by conventional and nukes do no leave a central peek and have relatively shallow slopes, while impact craters leave a peek and have very steep walls. This is because large impacts penetrate deep into the surface. A crater with a diameter of about 150K would have created a hole about 60km deep filled with vaporized rock which would quickly condense and fill the hole. My friend is without doubt that the images of CS craters chains where produce by fast moving heavy objects not explosives, ether chemical or nukes.
By the way it is easy to throw a hand full of gravel. Hold the gravel in your hand closing all but the index finger then throw letting the gravel come out of your palm along the finger. Using this technique you can constantly generate lines of impact. You must remember that when a comet breaks up it is due to tidal forces. Tidal forces stretch along one direction (direction of gravity). Just as when you stretch a rubber band it becomes long and thin. Then length expands while the width contracts. You may have heard of the most extreme case of this, called spaghettification as you come to close to a black hole. Space in a gravity field is stretched and squeezed. Thus you get a long line from a pile of stones.
There is also a boundary for each rubble pile around each planet that is the point where the tidal forces are greater then the bonding strength. The further a object travels inside this boundary the greater the rate of separation. If an object just skims this boundary it will separate very slowly producing CS crater chains.
