NASA Celebrates Life of Astronaut Gordon Cooper By PAM EASTON    HOUSTON (AP) -- Mercury program astronaut Gordon Cooper was remembered Friday by NASA officials and fellow space pioneers as "not too bad of a pilot, but a heck of a good astronaut."    Cooper, who on the final flight of the Mercury program became the first American to spend more than 24 hours in space, died of natural causes Oct. 4 at his home in Ventura, Calif...