Can Nano machines be made to eat through rock or metal? If so, can this concept be used to destroy a meteor?

Answer 1

yes in theory a small laser can be attached to nano machines to cut through matter, but we dont have the ability to create them yet.

However, this is not the best solution to destroying a meter, we could simply nuke it, or divert its dirrection if its in earths path

Answer 2

Err, we do not yet build nano machines. Not in any sense that you would understand from science fiction you may have watched. The key word here is fiction.

That said, the other two problems with this idea are that you would need huge numbers of such machines to make even the tiniest impact on a meteor, and they would consume a prodigious amount of energy. You cannot get around either of these because they are determined simply by the strength of rocks and the gravitational constant. And of course you have the substantial problem of getting them there, in tact.

So no.