Over 400 years after Galileo Galilei observed four main moons of Jupiter, scientists are gearing up to explore three of them to see if they could support life.
This week, the European Space Agency (ESA) is set to launch its JUpiter ICy moons Explorer (JUICE) spacecraft to explore three of Jupiter’s moons — Ganymede, Callisto and Europa.
Jupiter boasts over 90 moons, so what’s special about these three?
Thanks to Nasa’s Galileo spacecraft, evidence of liquid oceans hidden underneath the icy surfaces of these moons was revealed in 1995.
The discovery of liquid water, a key ingredient for life on Earth, so far out in space had scientists asking the obvious question: could there be life lurking somewhere in the depths of these icy oceans?
This is the question JUICE hopes to answer.
On April 13, the spacecraft will launch from the European spaceport in Kourou, French Guiana, hitching a ride into space on board an Ariane 5 rocket.
From there, it will take around eight years for the spacecraft to travel out to Jupiter, with an estimated arrival date in 2031.
UK’s contribution to JUICE
The UK’s contribution to the JUICE mission is a small but mighty instrument called a magnetometer, an instrument that measures magnetic fields in space.
Built in London’s Imperial University labs and in some people’s homes over lockdown, the instrument will serve a key purpose in studying the oceans on Jupiter’s moons.
‘The hardest thing that we are aiming to do is to try and measure the magnetic field from electrical currents that are flowing in the liquid water ocean on Ganymede,’ explains Professor Michele Dougherty, Principal Investigator for the magnetometer aboard JUICE.
‘That’s going to allow us to work out not only the depth of the ocean, but its salt content and hopefully get an idea about whether it’s a global ocean or whether it’s only focused at part of the moon,’
Could we actually find life on Jupiter?
If scientists had to bet on somewhere in the universe were life could form, the icy moons of Jupiter would be on top of the list.
‘We’re almost certain that at least three of the moons have good liquid water oceans underneath the surface. If we are looking for places in our solar system, where life can form, the first ingredient you’re looking for is liquid water,’ says Professor Dougherty.
They’re hoping JUICE will confirm this and if there’s a heat source and if there’s organic material on these moons.
‘Those three ingredients: liquid water, heat and organic material, are first needed, we think, for life to form. If those are stable enough over a long enough period of time, then potentially something might be able to happen,’
JUICE could provide scientists proof of whether these ingredients are there on the moons of Jupiter for life to form.
‘The mission will answer a lot of questions about whether you could find life potentially in a similar system with a gas giant like Jupiter and moons orbiting elsewhere in the galaxy,’ says Caroline Harper, Head of Space Science at the UK Space Agency.
A mission 30 years in the making
A planetary mission is a test of patience, a fact well-known to the scientists and engineers working on JUICE.
‘It’s going to take us seven and a half years to get to Jupiter. But in fact, you need a huge amount of patience to be involved in planetary missions,’ says Professor Dougherty who has been involved since the beginning stages of the mission back in 2007.
‘It’s taken us 15 years to get to the stage where we’re ready to launch and by the time we get to the end of the mission and we’ve taken all the data, it’ll be another 15 years. So we’re halfway through a 30-year mission,’
Clearly, patience is key.
After the launch this week, it’s going to be a long cruise to get to Jupiter but scientists are expecting activity ‘in bursts’.
Since the spacecraft can’t carry enough fuel to just fly straight to Jupiter, it will use gravity-assist flybys around the Earth and Venus to build up the momentum to get the spacecraft to Jupiter.
‘From about six months out, there will be science happening. It’s going to be busy in bursts and lots of testing, calibration, and commissioning ongoing in the intervening periods as well,’
We don’t know what JUICE will discover out there but scientists are confident that the data gathered from the mission could potentially alter our view of the Solar System, and our place in the universe.
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