 			force = new Three.Euler().setFromQuaternion(forceQuaternion)
 			@addAngularForce(force)
 
-			# Add thrust straight downward from the player.
+			# Add thrust straight downward from the player. If the player's boosting,
+			# the thrust will be significantly higher than then she's not.
 			thrustVector = new Three.Vector3(0, 1, 0).applyQuaternion(rotationQuaternion)
 
 			if @boost


			rotationQuaternion = new Three.Quaternion().setFromEuler(@rotation)

			# Check if the player is within landing range of the planet.
			if intersect = @getIntersect(@world.planet, 1, 2)
				@baseExtended = true
				@cannon.extended = false
				surfaceNormal = intersect.face.normal
			else
				@baseExtended = false
				@cannon.extended = true

				@addAngularForce(new Three.Euler(0, @cannon.rotation.y * 20 * dt, 0, 'YXZ'))
				@cannon.addAngularForce(new Three.Euler(0, -@cannon.rotation.y * 20 * dt, 0, 'YXZ'))

			# Update alien animation.
			@animation.update(dt)			

		# Fires a projectile when the cannon is ready, which is a fixed amount of time
		# after the last shot.
		#
		fire: ( ) ->
			if @_cannonReady and @cannon.extended
