Lancaster physicist Dr Chris Arridge has helped to develop instrumentation on board the European Space Agency’s rocket heading to Jupiter.

The JUICE (Jupiter Icy Moon Explorer) mission was on board the Ariane 5 spacecraft launched from the ESA’s spaceport in French Guiana.

It will investigate Jupiter’s main icy satellites Europa, Ganymede and Callisto as potential habitable bodies and in particular seek to understand their interiors and how they couple to the surface. JUICE will also explore Jupiter as an “archetype” for gas giant planetary systems – what can Jupiter and its planetary system tell us about gas giants in general, either in our solar system or further afield.

Dr Arridge is Reader in Planetary Physics at Lancaster University where he is a co-investigator on the JUICE magnetometer instrument “J-MAG” led by Imperial College London.

He said: “The spacecraft will take about eight years to reach Jupiter, but we will be doing science along the way. Once JUICE reaches Jupiter it will orbit the planet, doing quick flybys of the icy satellites, before going into orbit around Ganymede itself. It will end its mission with a controlled crash on the surface.”

J-MAG will measure magnetic fields around Jupiter and around Europa, Ganymede and Callisto. These measurements are important because, amongst other information, they yield information about salty liquid oceans underneath the icy crusts of the satellites. When these changing magnetic fields reach these icy worlds, they are modified by what they encounter inside – like a salt water ocean which is electrically conducting.

“By measuring how these changing magnetic fields are affected by the moons we can work out what is inside them. How thick the oceans are, how deep they are under the icy surface and how salty they are, for example.”

Ganymede - the largest moon in the solar system - is the main focus of the mission.

“Ganymede is the only moon in the solar system known to have its own magnetic field like that of the Earth. You could use a compass on Ganymede, just like you can on Earth. JUICE and J-MAG will also study this magnetic field and the consequences of Ganymede having its own magnetic field. For example, there are northern lights on Ganymede and JUICE and J-MAG will look at how these are produced.”

J-MAG is located on a 10.6m long arm that keeps the instrument far away from any sources of magnetic fields on the spacecraft that would otherwise contaminate the data.