ESA selects Juice: €1bn Juice probe to Jupiter

The European Space Agency (ESA) is to mount a billion-euro mission to Jupiter and its icy moons.

The probe, called Juice, has just been approved at a meeting of member state delegations in Paris.

It would be built in time for a launch in 2022, although it would be a further eight years before it reached the Jovian system.

The mission has emerged from a five-year-long competition to find the next "large class" space venture in Europe.

Juice stands for JUpiter ICy moon Explorer. The concept proposes an instrument-packed, nearly five-tonne satellite to be sent out to the Solar System's biggest planet, to make a careful investigation of three of its biggest moons.

The spacecraft would use the gravity of Jupiter to initiate a series of close fly-bys around Callisto and Europa, and then finally to put itself in a settled orbit around Ganymede.

Emphasis would be put on "habitability" - in trying to understand whether there is any possibility that these moons could host microbial life.

Callisto, Europa and Ganymede are all suspected to have oceans of water below their icy surfaces. As such, they may have environments conducive to simple biology.

"People probably don't realise that habitable zones don't necessarily need to be close to a star - in our case, close to the Sun," explained Prof Michele Dougherty, a Juice science team member from Imperial College London, UK.

"There are four conditions required for life to form. You need water; you need an energy source - so the ice can become liquid; you need the right chemistry - nitrogen, carbon, hydrogen; and the fourth thing you need is stability - a length of time that allows life to form.

"The great thing about the icy moons in the Jupiter system is that we think those four conditions might exist there; and Juice will tell us if that is the case," she reported.

The mission will cost Esa on the order of €830m (£695m; $1.1bn) over its entire life cycle. This includes the cost of manufacturing the spacecraft bus, or chassis, launching the satellite and operating it until 2033.

This sum does not however include Juice's 11 instruments. Funding for these comes from the member states. When this money is taken into account, the final budget for Juice is expected to be just short of €1.1bn.

It has not yet been decided which European nations will provide which instruments. An Announcement of Opportunity will be released this summer with a view to identifying the instrument providers by the start of next year.

The final and formal go-ahead for Juice should be given in 2014. In ESA-speak, this stage is referred to as "adoption".

It is the moment when all the elements required to build the satellite are in place and the full costings are established.

It is also the point at which any international participation is recognised.