John Travolta, 46, and Kelly Preston, 37, welcomed their second child yesterday, a nine-pound daughter named Ella Beau. The couple’s first born, son Jett, will turn 8 this month. John’s next movie is “Battlefield Earth,” a sci-fi extravaganza based on a novel by L. Ron Hubbard, the founder of the Church of Scientology, of which Travolta is a high-profile member. The flick opens May 12.