CAPE CANAVERAL, Fla. (AP) — A historic next-to-last space shuttle launch was scratched Friday because of mechanical problems, spoiling a visit from the president and dashing the hopes of the biggest crowd of spectators in years, including the mission commander's wounded wife, Rep. Gabrielle Giffords. NASA hopes to try again Monday to launch space shuttle Endeavour on its final voyage. President Barack Obama and his family visited Kennedy Space Center anyway but it was unclear whether he would meet with the Giffords.