collision and crash are nouns collide and crash (coincidently the same) are verbs. In this case you need a word for the action ie the verb. Therefore you can say "Satellites can crash" OR "satellites can collide". Satellites can collision is incorrect because you are using the noun form of this word.

Yes, "collision" is a noun. You need the verb. A note on Romulus' examples: by using "may", it simply indicates a crash is possible. By using "can" which is more generic, it could still mean a crash is possible, but also that satellites are capable of crashing. In an extreme case, this could mean that the satellites were designed to *only* crash into each other. :P

Thanks Peachey, I appreciate that! :)

it's simpler to say: "sattelites may collide." "sattelites may crash." :)