Billion euro ESA mission to explore icy worlds of Jupiter

Announced on 2 May 2012, at a meeting in Paris, ESA's Science Program Committee voted to go ahead with the project, the Jupiter Icy Moons Explorer (JUICE), the first European-led mission to the outer solar system, and the first spacecraft destined to orbit an icy moon.

The JUICE spacecraft is scheduled to launch in 2022, arriving in the Jupiter system in 2030. It will cost ESA c.830m euros (£695m; $1.1bn) and once the cost of the instruments aboard the spacecraft is factored in the total price of the mission will exceed one billion euros.

Professor Andrew Coates of UCL, a member of the ESA Science Study Team, said: "Studying these watery worlds is the next vital step beyond Mars in the search for the conditions for life in our solar system. Ganymede's unique magnetic shield helps protect it somewhat from Jupiter's harsh radiation belts and rapidly rotating magnetosphere, and we want to understand its effectiveness. Europa and Callisto provide key comparisons as we search for the solar system's 'sweet spots' for habitability."

UK researchers have been deeply involved in the leadership and planning for JUICE and have played a vital role in gaining approval for the mission ahead of rival bids. UK scientists make up four of the 15 members of the ESA Science Study Team for JUICE with the team including researchers from UCL (University College London), Imperial College London, Oxford University and University of Leicester.

The primary target of the mission is the solar system's largest moon, Ganymede, an icy world 8% larger than the planet Mercury. Ganymede is unique within the solar system - it is thought to harbour a deep ocean under the icy crust, it has its own internally generated magnetic field, and it has an ancient surface littered with more individual types of crater than anywhere else in the solar system.  

If moons are common features of giant planets around other stars, then Ganymede may represent a whole class of potentially habitable environments in our galaxy. JUICE will carry experiments designed to study the sub-surface ocean, the geology and composition of the surface, and its interaction with its plasma environment, to assess its potential as a habitable environment in our solar system. The spacecraft will also investigate Jupiter's other icy worlds, Callisto and Europa, as well as the giant planet's complex atmosphere and extended magnetosphere.

UCL, Imperial, Oxford and Leicester will be among the UK institutions working to propose experiments to be carried as part of the spacecraft payload. These instruments will be specifically designed to study the gas giant, its icy moons and charged particle environment to an unprecedented level of detail, giving our most detailed characterisation of the jovian system ever obtained.

As well as making close measurements of the surface, sub-surface, magnetic and plasma environment of Ganymede the mission will also focus on the other icy moons; performing multiple flybys of Callisto and two flybys of Europa. By studying all three of these icy environments the mission's studies of Ganymede will take on a broader significance.  

In order to assess whether Jupiter and its moons could provide habitable environments, and provide a model for gas giant systems orbiting other stars, the spacecraft will make an extensive study of the planet's dynamic, evolving atmosphere, with its belts, zones and gigantic swirling storms, over the 3-year duration of the mission. JUICE will also study the magnetic and charged particle environment of Jupiter, which has the largest magnetosphere in the solar system, and its coupling to the moons (particularly Ganymede).

The data JUICE will send back about the varied environments of Jupiter and its icy moons will benefit many areas of science with geologists, astrobiologists, space and atmospheric physicists all queuing up to see how the mission's findings will affect their disciplines.

The announcement will lead to further opportunities for British companies as they look to bid for contracts to build elements of the JUICE spacecraft and its instruments. The 2010 report 'The Size and Health of the UK Space Industry', commissioned by the UK Space Agency, estimated that the space industry's overall contribution to UK GDP is £6.9 billion and that it employs nearly 25,000 people.

Image: A composite image showing [L-R] the icy moons Europa, Ganymede & Callisto [credit: NASA]