Han Solo is solo once more, this time legally. Screenwriter Melissa Mathison, 51, who's been married to Harrison Ford, 59, for 18 years, filed for legal separation from the Oscar-nominated film star, seeking joint custody of the couple's two children, his spokesman said on Thursday. The petition was filed in Los Angeles Superior Court. The publicist, Pat McQueeney, said, "The couple is very friendly, and everything is very amicable." She added that Ford (who has homes in L.A., Wyoming and New York) would have no comment on his wife's petition and that he was currently in Los Angeles with Mathison and their two children: Malcolm, 14, and Georgia, 11. The two met on the set of "Apocalypse Now" and were married in 1983. They first announced their separation last November in a joint statement, saying that they were still trying to iron out their problems. By May, PEOPLE reported that the stay-at-home husband Ford had quietly reconciled with Mathison in March. "They're definitely back together," a source close to Ford told the magazine at the time. "He seems happier."