Since last spring, the Bush administration has been conducting a confidential effort to establish a dramatic new goal for the nation’s civil space program, perhaps rivaling President John F. Kennedy’s call to place a U.S. astronaut on the moon before the end of the 1960s, sources told United Press International. Only a few administration insiders have been involved, with Vice President Dick Cheney heading the effort, said sources, who requested anonymity. Though some details have leaked out — most notably reports Wednesday and Thursday that President George W. Bush will call for returning Americans to the moon — sources insist no final decisions have been made. Instead, the president is reviewing a list of alternative goals — some of them more practical than dramatic — that must conform to a pair of overriding directives: Any option must be achievable within a reasonable period of time, and it must not require any major new federal spending.