Europe is about to undertake one of its largest space missions ever to explore the icy moons of Jupiter.
The Juice satellite is undergoing final tests in Toulouse, France, and will then be sent to the launch site in South America.
It will leave Earth in April.
The six-ton spacecraft will make a series of flights to Callisto, Ganymede and Europa using an advanced suite of instruments to investigate whether any of these worlds are habitable.
This may sound imaginary. In the cold, outer reaches of the Solar System, the Jupiter system is far from the Sun and receives only a twenty-fifth of the light that falls on Earth.
But the gravitational compression and repulsion of the giant planet means they have the energy and temperature to hold large volumes of liquid water to their moons deep inside. And we know on Earth that wherever there is water there is an opening for life.
“In the case of Europa, there is thought to be a deep ocean perhaps 100km deep under the ice crust,” said mission scientist Prof Emma Bunce of the University of Leicester in the UK.
“The depth of the ocean is 10 times that of the deepest ocean on Earth, and we think the ocean is in contact with a rocky bottom. This provides a scenario where there is mixing and some interesting chemistry,” the researcher told the BBC. News.
A journey of 6.6 billion km, which took 8.5 years.
Mark the calendar for July 2031. That’s when Juice arrives at Jupiter. It will then make 35 flights over three months before settling permanently around Ganymede in late 2034.
The European Space Agency (Esa) project team behind Juice did a major review this week and concluded that the mission is to “go to launch”.
Aerospace company Airbus spearheaded the construction of the €1.6 billion (£1.4 billion; $1.7 billion) JUpiter ICy moons Explorer.
The manufacturer has drawn expertise and components from all over the continent.
Everything is now fully assembled, including Juice’s suite of 10 scientific instruments.
“We have a series of high-resolution cameras on this probe in all possible wavelengths – infrared, visible and ultraviolet,” said engineer Cyril Cavel, pointing to a series of boxes hanging from one side of the silver and black satellite. .
“You can see all these instruments under protective, transparent covers. The high-resolution visible telescope called Janus will take great pictures very close to the moon because we’ll only be flying at an altitude of 400km. There will be stunning shots,” said Airbus Juice project manager.
Radar will also peek inside the moons; lidar, a laser measurement system, will make 3D maps of their surfaces; magnetometers will monitor complex electrical and magnetic environments; and the sensors will sample the particles buzzing around them.
Juice will not look for specific “biomarkers”; will not attempt to detect foreign fish in the deep oceans. Its job is to learn more about the habitability possibilities that future missions can examine in more detail. Scientists have long considered the idea of puncturing the crust of one of Jupiter’s icy moons and landing to land in the water below.
This may be one day; in the second half of this century.
You need patience to work in the outer Solar System. The orbits of Earth and Jupiter may be “only” 600 million km away, but you can’t easily go straight without an enormous rocket. And while Europe’s Ariane 5 is mighty, it doesn’t have that kind of weight.
Instead, it will send Juice on a rather winding route that will use the gravity of Venus and Earth to launch the probe into the gas giant.
The juicer is built somewhat like an air-conditioned tank.
Unshielded, its electronics quickly decay in the harsh radiation swirling around Jupiter. And this long journey inward towards Venus and then into the gas giant will see temperatures on the moon’s outer surface swing from 250C to minus-230C.
“We have two large enclosures inside the spacecraft to protect the computers from radiation and keep them at the same temperature through a network of pipes,” said thermal architect Séverine Deschamps.
“The same goes for the propulsion system. It needs to be kept quite warm to operate, around 20C, to get a good level of performance when firing.”
Juice won’t be alone in her work.
The US space agency Nasa is sending its own satellite called Clipper.
Although it will leave Earth after Juice, it should actually arrive just before its European sibling. It will focus on Europe.
Together, the two satellites will form a strong team.
“When you put the two together, you get a much deeper understanding, and it removes some of the guesswork about what’s going on,” said Prof Michelle Dougherty, principal investigator of Juice’s magnetometer instrument.
“For example, it would be interesting if there is smoke coming from the moon as Clipper passes Europa. Clipper will take close measurements, but Juice will be watching from afar to see the effect it has on.” Whether we are larger spots in the environment around Europa and aurora lights on Jupiter.”