Destroy all the aliens surrounding the Kennedy and avoid the Kennedy to be
destroyed. You will have to destroy 15 to 19 aliens (or less if you
succeed in your first objectives). They are: 2 Skeeters, 5 Skimmers, 4
Submarines, 3 Scouts, 1 to 5 Cobras (depending on your previous
performances).
To end this final objective, you have to destroy the final Boss, named
"Morphing Tower". Don't get to close of it to avoid to start the morphing
operation.