Liquid water, a source of energy and nutrients are the three things scientists believe are necessary for life to emerge anywhere in the universe. Some of Jupiter's moons are more likely than others to provide all three of these elements. The European Space Agency's JUICE mission, set to launch this week, aims to help scientists better understand which of these moons possess the right stuff and could possibly support life, and which couldn't.
JUICE, however, is not going to detect life, nor its direct signatures, scientists say. And by the time the mission ends, most likely by crashing into Jupiter's largest moon Ganymede, we will still be decades away from knowing for sure whether life, even if only microbial, thrives on any of Jupiter's four main moons.
Many of the moons orbiting the giant planets of the solar system, such as Jupiter, Saturn and possibly Uranus, are quite different from Earth's moon. Data from probes that flew past them suggest that these moons may be harboring abundant oceans of water. Due to the extremely cold temperatures in these distant parts of the solar system, these oceans are covered by shells of ice dozens of miles thick, so peeking inside of those water bodies is not an easy task.
On some of these moons, such as Saturn's moon Enceladus, scientists have detected evidence of water geysers that spray upwards for miles into space through cracks in the ice. Measurements by the Hubble Space Telescope suggest that Jupiter's smallest moon Europa might also produce such plumes. These plumes indicate that some source of heat must be at work inside of those moons, increasing the possibility that conditions favorable for life might exist on these worlds.
Jupiter's largest moon Ganymede, the main target of the JUICE mission, is also believed to possess an ocean, and so might the most distant, crater-riddled Callisto.
JUICE will be studying these two moons from the altitude of several hundred miles, mostly measuring the physical properties that can help scientists confirm the existence of these oceans, determine their depth and gain some insights into their chemical composition. The probe will also make two flybys of Europa, the second closest of the four main moons to Jupiter. Despite the valuable measurements JUICE will take of these moons, scientists don't think that any signs of life could be detected from so high above.
Source: www.space.com
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