Even after Europe’s Jupiter Icy Moon Explorer (JUICE) mission is over a decade away, we’re unlikely to know for sure whether life could thrive near the largest planet in the solar system.
Liquid water, the source of energy and nutrients, are the three things scientists believe are necessary for life to emerge anywhere in the world. universe. A part of JupiterMoons of are more likely than others to provide all three of these. THE European Space Agency JUICE missionset to launch this week, aims to help scientists better understand which of these moons have the right things and could possibly support life, and which might not.
JUICE, however, will not detect life or its direct signatures, scientists say. And by the time the mission ends, most likely crashing into Jupiter’s largest moon Ganymede, it will take us decades to know for sure if life, even if only microbial, thrives on any of Jupiter’s four main moons. So what exactly is JUICE going to tell us?
Related: JUICE, ESA’s Jupiter mission, is not “powerful enough” to orbit the potentially life-bearing Europa. here’s why
Under the ice crust
Many moons orbiting the giant planets of the solar systemlike Jupiter, Saturn and eventually Uranusare quite different from earth moon. Data from the probes that have flown past them suggest that these moons may harbor abundant oceans of water. Due to the extremely cold temperatures in these remote parts of the solar system, these oceans are covered in shells of ice tens of kilometers thick, so it is not easy to peek inside. these bodies of water.
On some of these moons, like the moon of Saturn Enceladusscientists have detected evidence of water geysers that spray upward for miles into space through cracks in the ice. Measures by the The Hubble Space Telescope suggest that Jupiter’s smaller moon Europe could also produce such plumes. These plumes indicate that a heat source must be at work inside these moons, increasing the possibility that conditions favorable for life may exist on these worlds.
Jupiter’s largest moon, Ganymede, the primary target of the JUICE mission, is also thought to have an ocean, as does the more distant, crater-riddled one. Callisto.
JUICE will study these two moons at an altitude of several hundred kilometers, mainly measuring physical properties that can help scientists confirm the existence of these oceans, determine their depth and better understand their chemical composition. The probe will also make two flybys of Europa, the second of the four main moons closest to Jupiter. Despite the valuable measurements that JUICE will perform on these moons, scientists do not believe that signs of life can be detected from this high.
“If life exists on these moons, we expect it to be in water, and it’s very difficult to get to,” said Adam Masters, associate professor of spatial and atmospheric physics at the Imperial College London and a member of the team that built one of the science instruments for JUICE, Space.com told Space.com. “We do not expect life on the surface of these moons and it is not yet possible to descend [underneath the ice crust] where there could be life.”
The bad moon for life
Of the two missions planned to study Jupiter’s moons in the early 2030s, JUICE has a disadvantage when it comes to collecting evidence of extraterrestrial life. It is simply because the main objective of JUICE is Mercurythe size of Ganymede, the largest moon in the solar system and the third farthest from Jupiter among the planet’s four major natural satellites. NASA’s Europa Clipper The mission, which will launch next year but reach the Jupiter system a year before JUICE, has a better chance of yielding groundbreaking insights in this regard, as it focuses on smaller Europe. This moon, closer to Jupiter than Ganymede, is much more likely to possess the three main prerequisites for the emergence and existence of life, scientists believe.
“Evidence from previous missions as well as theory and modeling suggests that on Europa, under the ice shell, if you continue to descend into the water, you will eventually reach a rocky bottom,” Masters said. “That rock is the source of nutrients. And because we think there could be water plumes on Europa, just like on Enceladus, we think there must be a source of power. Ganymede, though. , is a different category.”
Ganymede, over 3,200 miles (5,200 kilometers) wide, has an ocean that is probably much deeper than that of smaller Europe. In fact, scientists believe that Ganymede’s ocean could hold 25 times more water than Earth’s ocean. But the immense depth of this body of water may be one of the reasons why life may not exist on this moon.
“What we think happens inside Ganymede if you go deep enough is that the water turns back to ice,” Masters said. “So the ocean of Ganymede not only has an ice shell above but also below, which means the water is probably not in contact with the rocky core.”
No rocky bottom means no nutrient source. However, adds Masters, all may not be lost for Ganymede as cracks may exist in the lower ice sheet, possibly created by some form of thermal activity within the core of the size moon. of a planet. Ganymede’s size, coupled with its greater distance from Jupiter (665,000 miles or 1,070,000 km compared to Europa’s 417,000 miles or 671,000 km), means that the intensity of tidal-producing gravitational forces to which Ganymede is subjected is much weaker than those that Europe experiments, which in turn could lead to less thermal activity inside the moon and therefore a lower probability of life.
Scientists are so convinced that there is no chance for JUICE to encounter anything alive around or on the surface of Ganymede that they plan to dispose of the spacecraft by crashing it into the moon. at the end of the mission. This maneuver aims to prevent JUICE from turning into an uncontrollable space junk that could potentially collide with the most promising Europe in the future and contaminate it with Earth germs.
“It would take a real shift in knowledge about Ganymede to put it in a different category,” Masters said. “If we find for example that there is not such a thick shell of ice or if we find that there is material on the surface coming from below and that Ganymede looks more like Enceladus and Europa, that could change things.”
So what is JUICE likely to find?
Although JUICE won’t land on Ganymede and will attempt to reach beneath the moon’s icy crust (which can be up to 90 miles or 150 km thick), its set of ten scientific instruments will allow scientists to glean a surprising amount information about the inner ocean of the moon.
One of the main questions scientists want the mission to answer is what the chemical makeup of the water under Ganymede’s icy crust might be, as it could hint at the moon’s ability to sustain life.
Remote analysis of the surface composition of the ice crust could provide clues, as could remote measurements of the magnetic field around the moon and its variations. Jupiter’s magnetic field is more than 10,000 times stronger than Earth’s. In the 1990s, NASA’s Galileo mission detected strange disturbances in this magnetic field that scientists ultimately attributed to the effects of the oceans inside Jupiter’s moons.
JUICE’s magnetometers are more sensitive than Galileo’s, and Masters hopes they will provide much more detailed views of the body of water beneath Ganymede’s icy shell. These sensitive instruments could even reveal, even through the tens of kilometers of ice, the amount of salt dissolved in the groundwater of the ocean.
“If there’s an ocean that has salt in it, that makes it electrically conductive,” Masters said. “Then we expect to detect some sort of very low frequency pulsating magnetic signal. It’s a very weak signal that’s quite difficult to resolve. But that’s where JUICE fits in. If it’s very, very salty, it will be more electrically conductive and the signal will be stronger, if it contains very little salt, it will be a weaker signal.
The chemical makeup of the hidden ocean can help scientists decide whether searching for life or its direct signatures with a future mission would be a worthwhile endeavour.
When will we know if there is life on Jupiter’s moons?
The data collected by JUICE and Europa Clipper will help scientists determine how best to search for direct traces of life in the Jupiter system in the future. Masters, however, warns that a mission that could provide the ultimate answer about life on Jupiter’s moons may still be a “generation away”.
“JUICE will set the stage for future missions that will search for biomarkers on these moons,” Masters said. “We don’t even know what these biomarkers should look like and there will be a lot of work done by our colleagues in life sciences and chemistry, trying to understand the implications of what JUICE will find and how it will turn out. perhaps integrates with what we know about life in extreme environments on Earth, like the bottom of Earth’s oceans.”
Even without the discovery of life, the JUICE mission should produce a wealth of fascinating scientific discoveries. In addition to the Galileo mission, NASA Junos spacecraft studied the Jupiter system, but the primary focus of this spacecraft was on the planet itself, rather than its moons. In the 1970s, the Pioneer 10 And Pioneer 11 and the Traveler 1 And Traveler 2 mission made brief visits to Jupiter, as did the Cassini Saturn Explorer and the new horizon probe to Pluto and beyond.
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