P8-6

Hint
"Save at least one cow!"

Solutions
Despite what the hint says, saving a cow (i.e. making it inaccessible to the alien so that it can survive indefinitely) is not enough. Rather the goal is to kill the alien.
 * Kill the Alien with a Blob/Ooze/Death, etc.
 * Suck it into a Black Hole.
 * Shoot it down with a weapon.