Excerpted from Aviation Week, June 3-16 2024, page 38:
Located more than five times farther away from the Sun than Earth, Europa seems an unlikely place to look for life. Surface temperatures on the ice-shrouded moon of Jupiter average |-260F, and radiation levels are high enough to kill a human being in one day.
But ever since NASAs Voyager flybys in 1979 and the flagship
1995-2003 Galileo mission to Jupiter, scientists have assembled an increasingly convincing body of evidence that beneath Europa's frozen surface lies a massive saltwater ocean containing 2-3 times the water in all the oceans on Earth.
Scientists suspect that Europas sea, which lies about 60 mi. beneath the surface, remains liquid due to the heat of tidal flexing as Jupiters gravity stretches and squeezes the moon. Europa, with a diameter of about 1,900 mi.slightly smaller than Earths Mooncircles Jupiter every 3.5 days. Like Earths Moon, Europa is tidally locked, resulting in one hemisphere always facing Jupiter. Tidal forces on Europa are about 1,000 times stronger than the Moons effect on Earth.
Europas surface is youngjust 40-90 million years old but its inner ocean is believed to have existed for billions of years, long enough for the chemistry of life to evolve. And while there is no evidence of life on Europa, scientists suggest the moon may have environments similar to Earths deep-ocean hydrothermal vents, where unique ecosystems thrive despite extreme temperatures and pressures, toxic minerals and no sunlight.
Observations by NASAs Hubble Space Telescope in 2012 and 2014 also suggest water from inside Europa may intermittently vent into space as plumes, similar to what the Cassini spacecraft has observed on Saturns moon Endeladus. Astronomers estimate Europas plumes rise about 125 mi. into space before raining material back down onto the moons surface.
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If it turns out that there is life in the ocean of Europa, which has existed for something like four billion years, it supports the general idea of "random but inevitable" theories of Abiogenesis.
Joe Gwinn