Juice, a European Space Agency (ESA) spacecraft, is getting ready for its journey to Jupiter in a mission to find out if any of the giant planet’s three ocean-bearing moons are habitable.

Scientists in the UK have led the development of one of the 10 instruments on the spacecraft, while the UK Space Agency provided £9 million of funding for the £1.4 billion project.

Juice, which stands for JUpiter ICy moons Explorer, is due to blast off on April 13 from French Guiana, with an eight-year journey ahead.

Experts from Imperial College London led the development of the magnetometer, known as J-MAG, which will measure the characteristics of the magnetic fields of Jupiter and its largest moon, Ganymede.

It will also play a key role in detecting moving salts in the oceans beneath the icy crusts of Ganymede as well as exploring Jupiter’s other moons, Europa and Callisto.

The data will help characterise the depth and salt content of Ganymede’s ocean, to see if it may hold the conditions for life.

Professor Michele Dougherty, head of the Department of Physics at Imperial College London and principal investigator for J-MAG, said: “With our instrument’s measurements, we are almost looking inside these worlds.

“What we’re doing however is extremely difficult, as the signals we’re trying to detect are extremely small.

“It’s like trying to find lots of needles in a haystack, and those needles are changing shape and colour all the time.

“But we think the results are going to be spectacular.”

Prof Dougherty and her team will be collaborating with experts from the University of Leicester as well as the University College London (UCL).

Juice spacecraft being prepared for launch
Juice spacecraft being prepared for launch (ESA/CNES/Arianespace)

Professor Emma Bunce, director of the Institute for Space at the University of Leicester and co-investigator on J-MAG, said: “After many years of hard work from science, engineering, and industry teams, we are so excited that the Juice mission is finally ready to launch and start its long journey to the Jupiter system.

“We will patiently await the incredible data that we expect to receive from 2031, and we are confident that it will absolutely be worth the wait.”

As well as J-MAG, Leicester’s scientists will also collaborate with other experts on two other instruments on Juice: MAJIS (the Moons and Jupiter Imaging Spectrometer) – which will observe cloud features and atmospheric constituents on Jupiter; and UVS (UV imaging spectrograph) – which will characterise the composition and dynamics of the exospheres of the icy moons.

Meanwhile, the UCL’s Mullard Space Science Laboratory (MSSL) has provided particle detectors for Juice’s PEP (Particle Environment Package) instrument, which will gather data on “the ‘soup’ of ions, electrons, and atoms surrounding Jupiter and its moons”.

Professor Geraint Jones, of MSSL and a co-investigator on the PEP instrument, said: “This data will help us, for instance, to understand how particles around Jupiter reach such high energies – energies that could be fatal for an astronaut.

“We are excited that the mission will shed new light on worlds that could potentially host life.”

The MSSL, along with the Open University, also have science roles in Juice’s optical camera system called Janus.

Dr Chiaki Crews, research fellow at The Open University, said: “The Juice mission aims to answer many exciting questions, including whether the ocean worlds beneath the surfaces of Jupiter’s icy moons could potentially harbour life.

“One of the many instruments needed to make detailed scientific observations to help answer such questions is a camera.

“A large part of our work was to irradiate test sensors with high doses of radiation, just like it is expected to experience during the Juice mission lifetime, to check that Janus will still be able to take images without too much degradation.”