The European Space Agency is launching a mission on Wednesday to investigate the emergence of habitable worlds around gas giants such as Jupiter, the largest and fastest-spinning planet in our solar system.
The craft named JUICE (the Jupiter Icy Moons Exploration) will travel more than 884 million kilometres to fly past Jupiter and its ice-encrusted moons, Calisto, Europa and Ganymede.
Once it reaches orbit, around 2031, the craft will unfurl ten giant solar panels and a boom pole carrying instruments to measure elements of its surroundings.
Then it will spend several years orbiting Ganymede which has sparked the most interest among space scientists at the European Space Agency.
Dr Caroline Harper, the Head of Space Science at the UK Space Agency believes it will confirm the existence of salty oceans beneath the surface of Ganymede: “JUICE is not in itself designed to look for life on an icy moon, but if we’re going to find life elsewhere in the solar system, chances are it’s going to be underneath the ice, if there is an ocean, underneath the ice on one of those moons.
“So it’s going to be very exciting to look and see whether we do find what we expect to find, whether there are salty oceans under the icy crust that could contain the conditions that support life,” she said.
Attached to the boom will be a large magnetometer which will measure magnetic fields in the Jovian system.
Jupiter’s magnetic field is thousands of times stronger than Earth’s. It protects the planet from solar winds.
The magnetometer was designed by the physics department at Imperial College London.
Professor of Space Science, Michele Dougherty says information gleaned about the environment around Jupiter can inform researchers about other similar gas giants beyond our solar system.
At the core of the mission is the desire to discover whether there are other habitable worlds like our Earth around gas giants like Jupiter.
“The moons themselves, we want to understand what the interior structure looks like and whether the ingredients for potential habitability are there, but the other reason that Ganymede is so important is that we think the internal structure of Ganymede is a whole new class of body known as a water world,” said Dougherty.
She explained: “Right at the end of the mission we will go into orbit around Ganymede and what that will allow us to do is, first of all, confirm what the ocean depth is, also confirm what the salt content is, so how much conductivity there is.
“We will also confirm how deep the ice crust is above the ocean and then in combination with other instruments we hope to be able to work out whether it’s a global ocean, whether that ocean is in contact with the silicate mantle right deep in the interior. So, maybe some salts are leaking out, but then some of the other instruments will be able to see whether there’s organic material on the surface” she added.
JUICE won’t be attempting to land on any of the moons, but Dougherty said the instruments on board will give us important information about the potential for emerging life.
“If you’re looking for ingredients for life or for potential habitability to form you need four different things, the first ingredient is liquid water, the second one is a heat source, which we’re almost sure we have at Ganymede because there’s this internal dynamo field and organic material. Then those first three ingredients will need to be stable enough for a long enough period of time so that something can actually happen.”
Scientists like Dougherty know they won’t discover the answers to the questions they’ve posed for many years, but they believe there is still a good cause for the mission.
“Carbon, nitrogen, methane, what that will tell you is the conditions are there for bacteria to be able to form. So we know in the deep oceans on the Earth there are hydrothermal vents where organic material and bacteria are found. So that could be what we think is going on at Ganymede.”
Given the time and energy spent on the mission, it’s frustrating for scientists not to be able to plant a craft on Ganymede.
But Dougherty says the first JUICE mission is essential for that to happen.
“We won’t get under the surface with JUICE, but what JUICE will be able to tell us is how thick the ice crust is, so if we want to go back again and send a lander at least we know where to land. I’m often asked, why aren’t you sending a lander now? We don’t know where to land” she said.
The JUICE craft is scheduled to launch from Kourou in French Guiana but there are already other missions set to launch this year.
“They’re called Plato and Ariel. Plato will go and search for rocky Earth-like planets orbiting other stars, and Ariel will characterise the atmospheres of around a thousand different exoplanets” concluded Harper.