CAPE CANAVERAL, Fla. (Reuters) - NASA said on Friday it would be at least late next week before the first shuttle mission since the 2003 Columbia accident can be launched, after Discovery's liftoff was postponed two days ago because of a fuel sensor problem. "The simple things did not provide us any resolution to the problem," said deputy shuttle program manager Wayne Hale. The sensors are designed to shut off the shuttle's three main engines before fuel runs out to avoid damaging them. A premature shutdown could force a shuttle to make an emergency landing or prevent it from reaching...