Combining the spriteSheets with the frames as an array of images seems to provide better performance. No example is really complete without the use of particles so I had to add some fun there. The ship uses atan2 to generate the angle between the sprite and the mouse location. Then the ship adjusts its Y location progressively in relation to the mouse continually adjusting its angle for a smooth and gentle movement. The sprite animations were made in Adobe Flash and used the CS6 generate spritesheet method.

Check it out: spriteSheet Alien Invasion