The U.S. space agency NASA has launched an unpiloted probe on the first-ever mission to study the distant planet of Pluto.
NASA says it will take the New Horizons probe nine years to make the journey.
It blasted off from Florida Thursday on a powerful Atlas rocket, and soon reached a speed of 58,000 kilometers per hour, the fastest spacecraft ever launched.
Technical and weather problems twice delayed the launch earlier this week.
NASA says the probe will cross the solar system, and conduct flyby studies of Pluto and its moon Charon in 2015.
It says the piano-sized spacecraft will get a slingshot-like gravity boost when it reaches Jupiter next year, saving significant flight time during the 700-million dollar mission.