NASA鈥檚 New Horizons spacecraft embarked upon a nine-year, five-billion-kilometre journey to Pluto on Thursday.
The Atlas 5 rocket carrying the probe blasted off from Cape Canaveral in Florida, US, at 1900 GMT (1400 EST), marking the start of an epic journey to the edge of the solar system. The probe will be the first spacecraft ever to visit the solar system鈥檚 smallest, most distant planet.
Some ashes of Pluto鈥檚 discoverer Clyde Tombaugh, who died in 1997, are hitching a ride on the spacecraft. 鈥淎nd it鈥檚 really quite an honour,鈥� says New Horizons principal investigator Alan Stern, of the Southwest Research Institute, US.
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The probe is also carrying 10.9 kilograms of radioactive plutonium dioxide fuel, which will provide power for instruments and subsystems as it flies through the outer reaches of the solar system, where the Sun鈥檚 rays are too faint to power solar panels.
NASA had calculated a 1 in 350 chance of a launch-area accident that would release the radioactive element. But everything went smoothly as the rocket carrying the probe lifted off from its launch pad.
鈥淚n general, the spacecraft is now in the safest place it could be 鈥� on its way to Pluto,鈥� says Glen Fountain, the New Horizons project manager.
Jupiter flyby
NASA had hoped to begin the $700 million mission on Tuesday but high ground winds scuppered the launch. Then, on Wednesday, a storm caused a power outage at the Johns Hopkins University鈥檚 Applied Physics Laboratory in Maryland, US, from where the spacecraft will be operated, causing launch to be delayed another 24 hours. The launch was delayed again on Thursday, for an hour, to allow time for low clouds to disperse.
New Horizons then separated from its rocket鈥檚 third stage roughly 45 minutes after take off. It was expected to speed past the Moon鈥檚 orbit 9 hours after take-off and the first engine firing to adjust its path is expected to be in nine days.
Its next planetary pit stop will be a flyby of Jupiter in February 2007. The planet鈥檚 massive gravity should accelerate New Horizons to a blistering 21 km per second (47,000 mph), which will enable it to reach Pluto as much as five years earlier than otherwise.
During its brief time near the giant planet, the spacecraft will study its meteorology, auroras, magnetosphere and the dust around both Jupiter and its moons.
Global maps
After the fly-by, mission managers will put New Horizons to sleep for the rest of its journey to Pluto. But they will wake it up once a year to ensure its systems are operating properly and to make any necessary corrections to its trajectory.
New Horizons will begin observing Pluto, its moon Charon, and two smaller moons in January 2015 and will make its closest approach on 14 July 2015. As it approaches Pluto, New Horizons will make global maps of both it and Charon, and will study the planet鈥檚 atmospheric and surface composition.
NASA may then decide to extend the probe鈥檚 mission, sending New Horizons to one or two other objects in the Kuiper Belt 鈥� the ring of icy bodies surrounding the solar system beyond Pluto.
