I was wondering about the feasibility of an idea I had about deflecting Asteroid/Comets from hitting Earth.

My idea is this: Transport water into Earth orbit, L1. Set a nuclear style heater in the center of the mass of water.
The heater would not activate until the radioactive rods moved into place.

The water would freeze around the "Heater" in space, more water would be added until a large mass of frozen water was made, strap on a large ion engine and accelerate the mass toward the Asteroid/Comet, which would hopefully have been tagged with transponders.

Before it collided melt the ice into a blob of water and let that collide.
That should keep the Asteroid/Comet body from fragmenting and having multiple fragments strike the planet.