- By Jonathan Amos
- BBC Science Correspondent
Europa’s mission has blasted off to Jupiter’s icy moons far from Earth.
The Juice satellite was sent into the sky on an Ariane-5 rocket from the Kourou Spaceport in French Guiana.
There was joy, applause, relief and many hugs at Kourou Station after it was confirmed that it had successfully completed the phased separation process.
This is the second time the European Space Agency (ESA) project has been so lucky after Thursday’s launch attempt was halted by weather.
Juice was called home shortly after coming off Ariane’s top. Then came confirmation that their massive solar array system had been deployed correctly, too – every 90 square meters of it.
“We have a mission; we fly to Jupiter; we go fully loaded with questions. The juice is coming, Jupiter! Get ready for it,” declared Andrea Acomazzo, director of operations at the ESA Mission Control Center in Darmstadt, Germany.
The agency’s director general, Dr Josef Achbacher, also expressed pride that the €1.6 billion (£1.4 billion; $1.7 billion) mission was safely on its way.
“But I have to remind everyone, there is still a long way to go,” he said. “We have to test all the instruments to make sure they work as expected, and then, of course, we get to Jupiter. But we’ve taken a very big step toward our goal.”
The Jupiter Icy Moon Explorer (JUICE) is sent to the largest planet in the solar system to study its main moons – Callisto, Ganymede and Europa.
These icy crust worlds are thought to hold huge reservoirs of liquid water.
Scientists are intrigued to see if moons might host life, too.
This may sound fancy. Jupiter is located in the cold, outer regions of the solar system, far from the sun and receives only 25 times as much light as Earth.
But the gas giant planet’s gravitational pressure on its moons means they likely have the energy and warmth to drive simple ecosystems — such as those around volcanic vents on Earth’s ocean floor.
“In the case of Europa, it is believed that there is a deep ocean, perhaps 100km deep, beneath its icy crust,” said Professor Emma Pons, from the University of Leicester, UK.
“This ocean depth is ten times the deepest ocean on Earth, and the ocean is in contact, we think, with a rocky floor. This provides a scenario where there is mixing and some interesting chemistry,” the researcher told the BBC. News.
Ariane doesn’t have the heft to send the juice straight to its destination, at least not in a useful timeframe.
Instead, the rocket will send the spacecraft on a trajectory around the inner solar system. Then, a series of flybys of Venus and Earth will gravitationally guide the mission to its intended destination.
It’s a journey of 6.6 billion kilometers that takes 8.5 years. The Jovian system is expected to be reached in July 2031.
The ice-covered moons Callisto, Ganymede, and Europa were discovered by the Italian astronomer Galileo Galilei in 1610, using the recently invented telescope. He can see them as small points orbiting Jupiter. (He can also see a fourth body we now know as Io, a much smaller world covered in volcanoes).
The diameter of the ice trio ranges from 4,800 km to 5,300 km. To put this in context, Earth’s natural satellite is about 3,500 kilometers across.
Juice will study the moons from a distance. This means that they will fly over their roofs; won’t land. Ganymede – the largest moon in the solar system – is the ultimate goal of the satellite. It will end its tour by going into orbit around this world in the year 2034.
Radar will be used to see the moons. lidar, a laser measuring device, will be used to create 3D maps of their surfaces; Magnetometers will explore their complex electric and magnetic environments; Other sensors will collect data on the swirling particles that surround the satellites. The cameras will, of course, send back countless pictures.
Juicy won’t be looking for specific “vital signs” or trying to find exotic fish in the ocean depths.
Its mission is to gather more information regarding habitability so that subsequent missions can address the question of life more directly.
Scientists are already thinking about how to put landers on one of Jupiter’s frozen moons to drill through its crust to the water beneath.
In the planet’s Antarctica, researchers are using heat to burrow hundreds of meters through the ice sheet to deploy submersibles into places where the local ocean freezes over.
It’s tough work, and it would be an even bigger task on the Jovian moon, where the ice crust could be tens of kilometres.
Juice will not be alone in his work.
NASA is sending its own satellite, Clipper.
Although it will leave Earth after juicing, next year it is supposed to arrive before its European sister. It has the advantage of launching a more powerful missile.
Clipper will focus its investigations on Europa, but will do the same work.
“There is great integration and the teams are very keen to collaborate,” said Professor Carol Mundell, Director of Science at the European Space Agency.
“Certainly, there will be a wealth of data. But, first, we have to make sure our missions get to Jupiter and operate safely,” she told BBC News.