Quite obviously, a case of Newton's third law of motion. The bug hit the windshield and the windshield hit the bug. Depress mouse to see answer. Each force is the same size. The fact that the bug splatters only means that with its smaller mass, it is less able to withstand the larger acceleration resulting from the interaction.
Rockets do accelerate in space.
Depress mouse to see answer. It is a common misconception that rockets are unable to accelerate in space. The fact is that rockets do accelerate. Rockets are able to accelerate due to the fact that they burn fuel and push the exhaust gases in a direction opposite the direction which they wish to accelerate. A gun recoils when it is fired.