[RWebb]

a large object may not skip like a tiny shuttle

a large one would ideally be intercepted and moved into a different orbit by placing rocket motors on it

or drill into it and blow off shards repeatedly...

speed is relative - so you do the intercept far enuff away that you can match speeds

of course, HOW are you going to carry all the 'stuff' you need way up out of Earth's gravity well??

if a big one is on track to splat this planet, then we would be nearly as helpless as the dinosaurs...