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ESA's Juice blasts off to squeeze secrets from Jupiter's moons

Few orbital boosts and we'll get the snaps in eight years

The European Space Agency's Juice probe began its eight-year trek to study Jupiter and its major moons on Friday, after launching into space aboard an Ariane 5.

The heavy-lifting rocket blasted off from Europe's spaceport in French Guiana at 1414 CEST (1214 UTC or 0814 ET) today. ESA had hoped to send Juice off into space earlier this week, though the flight was postponed due to risk of lightning. 

Mission control working at the agency's European Space Operations Centre confirmed the spacecraft launched successfully, and has now spread its 27-metre-long solar arrays. Juice will get its instruments into gear over the next two-and-a-half weeks and then shift between hibernating and performing maneuvers to take it to Jupiter. The next major milestone will be a lunar-Earth flyby in April 2024, its first out of four gravity assist operations that will nudge it toward the gas giant.

"Over the next six years the spacecraft needs to conduct several flybys around Earth and Venus in order to gain sufficient energy to arrive at Jupiter by 2031," Gaitee Hussain, ESA's Head of the Science Division, told The Register.

"A particular challenge is the flyby around Venus during which the spacecraft will be subjected to a temperature as high as 250 degrees C. We need to use Juice's 2.5-m high-gain antenna, which resembles a dish, as a sunshield to protect the sensitive instruments, which are designed to work at the much lower temperatures of the outer solar system as low as -230 degrees C."

On top of extreme temperature fluctuations, Juice will have to deal with Jupiter's intense magnetic field and high radiation and plasma levels. Engineers at ESA made sure to shield the probe's hardware and avoid Juice staying too long in the Solar System's most treacherous regions to prevent frying its electronics, particularly around Jupiter's Europa moon where it will only perform flybys.

"The spacecraft has been built with considerable shielding, the most sensitive electronics are inside twin vaults inside the body of the spacecraft which are reinforced with lead. If they could not be placed in the vaults because of the measurements they have to make, other components have been given spot shielding using heavy material to help protect them," Hussain said.

Juice is set to turn on its instruments and begin its science operations when it approaches Jupiter. It will spend six months orbiting the largest planet in the Solar System before observing Europa, Callisto, and Ganymede, the Jovian moons astronomers have managed to detect liquid oceans beneath their icy shells. Juice will also probe the volcanically active Io and other smaller natural satellites: Metis, Adrastea, Amalthea, and Thebe.


ESA's Juice to probe Jupiter's moons for signs of possible life


Juice's main goals are to understand how gas giant systems form, and if Jupiter's moons are or were potentially habitable for life of any form. The spacecraft won't be able to confirm direct evidence of alien life, and is instead designed to map any liquid water present and detect any biosignatures present. 

Biosignatures being chemicals or features that point to the presence of past or present life.

"A fundamental question that humans have asked themselves is, are we alone? In 1995, astronomers reported the first discovery of a planet around a star like the Sun, not even 30 years have passed but a number of different ingenious techniques have been deployed to discover well over 5,300 planets around other stars," Hussein said.

"The sheer diversity of the systems that have been uncovered raises the question of how unique our solar system is. ESA's science program is addressing this question with a variety of missions that probe not only the places in our solar system which may host or have hosted life, but also the places around other stars."

ESA's Director General Josef Aschbacher said in a statement: "Juice's spectacular launch carries with it the vision and ambition of those who conceived the mission decades ago, the skill and passion of everyone who has built this incredible machine, the drive of our flight operations team, and the curiosity of the global science community. Together, we will keep pushing the boundaries of science and exploration in order to answer humankind's biggest questions." ®

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