sure , its gray hull bristled with gun turrets and ray cannons and its force field glowed a fiendish , sickly green , but there was a weakness in the field , a hole only two inches wider than his fighter , that if he hit just right ... and he 'd have to hit it just right , because the whole squadron had been wiped out , he was down to his last missile , and there was no one left to defend the earth from the alien horde but him , sammy `` the viper '' sullivan .