CAPE CANAVERAL, Fla. - It will be the fastest spacecraft ever launched, zooming past the moon in nine hours and reaching Jupiter in just over a year at a speed nearly 100 times that of a jetliner. Its target is Pluto — the solar system's last unexplored planet, 3 billion miles from Earth. And the New Horizons spacecraft, set for liftoff on Tuesday, could reach it within nine years. Pluto, a tiny, icy misfit of a planet — some say it's not a planet at all — neither resembles the rocky bodies of Mercury, Venus, Earth and Mars, nor the...