Move over Mars. The search for extra-terrestrial life in our solar system is this week fixed squarely on Jupiter as the European Space Agency (ESA) gets set to send its Juice spacecraft on an ambitious mission to inspect the frozen oceans of three of the planet’s moons.
The Jupiter Icy Moons Explorer – which blasts off on Thursday from French Guiana and won’t reach its destination until the year 2031 – is suped up with the most powerful remote sensing, geophysical and in situ instruments ever transported to the outer solar system.
This will allow the Airbus-built machine to carry out a detailed survey of both the giant gas planet itself and its three large ocean-bearing “Galilean” moons, Ganymede, Callisto and Europa, which are being viewed as dwarf planets with the potential to harbour alien life.
Huge challenges
While Europa is the most likely candidate for life, massive levels of radiation mean it won’t be possible for Juice to enter into orbit says Gabriel Tobie, a planetary scientist at the University of Nantes in France.
“This is why we will fly round Europa only twice … and then focus on the outer moons Ganymede and Callisto, where the radiation is much weaker,” Tobie told RFI.
Information about the seismic surface of Europa will be collected using spectral imaging cameras.
"If we are lucky, we may be able also to detect eruption," Tobie says, adding that one of the major challenges will be determining the depth of the ocean below the icy shell on the three moons.
"To do that we use what's called 'geophysical measurement'. So we measure the magnetic field, the gravity field, and the topography. By combining this information, we'll be able to tell how deep the ocean is, and get information about the composition of the ocean.
"We'll be able to know if the ocean is very salty or not very salty, and if it's comparable to the oceans on Earth."
What makes #Jupiter's climate so exotic & extreme compared to our own? And could we some day have Jupiter weather forecasts?
— ESA's Juice mission (@ESA_JUICE) April 9, 2023
Find out how #ESAJuice will study Jupiter's atmosphere from @LeighFletcher @UniOfLeicester, Juice interdisciplinary scientist 📽️👇 pic.twitter.com/g14cnD8kRG
After a sequence of some 35 flybys, Juice will be sent into orbit around Ganymede, the largest of Jupiter’s satellites and the only moon known to have its own magnetic field – which protects it from harmful radiation.
This accomplishment will make Juice the first spacecraft to orbit the moon of another planet.
Modest fuel
Discovered by Italian astronomer Galileo more than four centuries ago, Jupiter's icy moons are so far away from the Sun that our star appears as a mere “spotlight in the sky”, astronomers say.
Little solar energy is able to travel that distance.
The first mission launched with the specific aim of exploring these remote worlds also presents as a major technological feat.
Not only does Juice require a “nuclear bunker” to protect its precious equipment from radiation, it must also complete its decade-long mission with modest fuel supplies.
"When its launches, there will be about three tons of fuel inside Juice, and most of this fuel will be used for the transfer to Jupiter," Tobie explains, adding the fuel will also be needed to put the vessel into orbit around Jupiter and later around Ganymede.
"This is because in order to go into orbit we need to use the fuel to slow down the spacecraft."
Juice's impressive solar panels will be used to power the instruments and electric systems onboard – but despite their 85-metre size, they only produce about a thousands watts, says Tobie.
"That's comparable to the energy used to power a hairdryer."
Alien life?
The burning question of whether life exists outside our home planet has been the source of fascination and speculation for centuries. By the end of its mission, Juice may be able to offer some concrete answers.
What are the chances that our far-flung Jovian system is home to some kind of life?
"That is difficult to determine," says Tobie.
"What we're doing is determining what the chances are of getting information about this possibility ... Juice will be able to tell us where to look."
