NASA on Friday launched the billion-dollar solar-powered spacecraft Juno on a five-year journey to Jupiter.

The unmanned satellite observatory shot into space aboard a 197-foot-tall (60 metres) Atlas V rocket, blasting off from the Cape Canaveral Air Force Station in Florida at 12:25 p.m.

“Ignition and lift-off on the Atlas V with Juno on a trek to Jupiter, a planetary piece of the puzzle on the beginning of our solar system,” said a NASA television commentator.

Once it arrives in July 2016, the spacecraft will orbit the poles of the gas giant, which has more than twice the mass of all planets in the solar system combined and is believed to be the first planet that took shape around the Sun.

Named after the wife of the Roman god Jupiter, the $1.1 billion spacecraft is NASA's first mission to the planet since Galileo was launched in 1989. It aims for 30 orbits over a period of one year.

Juno will get closer to Jupiter than any other NASA spacecraft has and will be the first to undertake a polar orbit of the planet, said Scott Bolton, Juno principal investigator and scientist at the Southwest Research Institute in San Antonio, Texas.

“One of the primary goals of Juno.... is [probing] the origin of Jupiter and the origin of our solar system,” Mr. Bolton said just before the launch.

“Juno is set up to learn about that early part of the solar system and learn how Jupiter formed and by measuring the ingredients. We are really looking for the recipe of planet formation.”

The orbiter Galileo entered the planet's orbit in 1995 and plunged into Jupiter in 2003, ending its life.

Other NASA spacecraft — including Voyager 1 and 2, Ulysses and New Horizons — have done flybys of the planet.

Juno will spend the first two years of its mission going around the Sun, then return for a flyby of the Earth, which will give a gravitational boost to accelerate the spacecraft on a three-year path toward Jupiter.

When it gets there, Juno — orbiting around 5,000 km (3,100 miles) above the gas giant — will make use of a series of instruments, some of which were provided by European space agency partners in Italy, Belgium, France and Denmark, to learn about the workings of the planet and what is inside.

Two key experiments will gauge how much water is in Jupiter and whether the planet “has a core of heavy elements at the centre, or whether it is just gas all the way down,” Mr. Bolton said at a press briefing last week.

Scientists also hope to learn more about Jupiter's magnetic fields and its Great Red Spot, a storm that has been raging for more than 300 years.

“One of the fundamental questions is how deep are the roots to that red spot? How does it maintain itself for so long?" said Mr. Bolton.

Juno is carrying a few toys as part of a campaign to raise awareness among young people about math and science.

Three 1.5 inch figurines made by LEGO toys are on board — a likeness of the Italian astronomer Galileo Galilei, who discovered four of Jupiter's moons, the Roman god Jupiter, and his wife Juno.

Back in 2003, when plans for Juno were being crafted, NASA briefly considered using some sort of nuclear fuel to power the spacecraft, but engineers decided it would be quicker and less risky to go with solar.

Juno is part of a series of new planetary science missions, to be followed by GRAIL (Gravity Recovery and Interior Laboratory), which is headed to the moon in September, and the Mars Science Laboratory set to take off in November.

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