In Mission 7 - This Island Suburbia, you are required to destroy Ice Cream Vans using the saucer. During this, you are introduced into the Repulse-O-Tron. This destroys any incoming missiles that are in range of you.
You will encounter SAM launchers, which will fire rockets at you. Once they are close, press
to activate the Repulse-O-Tron and destroy the rocket and the achievement will pop.
If you mess up the timing, just try again, there are many occasions where you will ahve rockets fired at you