Cape Canaveral, Fla. ? High winds forced NASA to scrub the launch Tuesday of an unmanned spacecraft on a nine-year, 3-billion-mile voyage to Pluto, the solar system’s last unexplored planet.

NASA planned to try again today to launch the New Horizons probe, although the forecast held a greater chance of thunderstorms, clouds and gusty winds that could prevent a launch.

On Tuesday, winds exceeded the space agency’s 38 mph flight restriction.