The icy moon that defies the rules of space geology
In short: While humans dream of red deserts on Mars, a hidden world in Jupiter's orbit may hold the solar system's greatest secret. Beneath a shell of ice lies a planetary aquarium containing more water than all of Earth's oceans combined, potentially harboring life in a vast, hidden interior.
For centuries, Europa was a mere speck of light, barely distinguishable from a sixth-magnitude star. Discovered by Galileo in January 1610, it was initially categorized as the smallest of the four Galilean moons. By the late 1800s, scientists estimated its diameter at roughly 3,100 kilometers (1,926 miles), leading many to assume it was a dry, crater-scarred wasteland similar to our own Moon. It was identified as the second moon from Jupiter by distance. This tiny point of light remained a mystery for nearly four hundred years.
The narrative shifted in the 1960s with the advent of spectroscopy, which suggested the surface was composed of ice rather than rock. However, it wasn't until the Voyager missions in 1979 that the true nature of the moon was revealed. While Voyager 1 captured the other Galilean satellites, Voyager 2 provided the first close-up look at Europa, revealing a landscape that defied geological expectations. Voyager 1 reached the region in March of 1979 to photograph its neighbors. Voyager 2 arrived later that same year in July to fly by Europa.
The most striking feature of Europa is the near-total absence of impact craters. On a body with no significant atmosphere, such a lack of scarring suggests a dynamic, changing surface. Instead of craters, the ice plains are marked by thousands of dark streaks and long scars that appear to tear open the crust. These features suggest that material from deep within the moon is being pulled to the surface, hinting at a complex, active interior that keeps the moon's face perpetually renewed. The reddish network of streaks overlaps across the icy plains. These markings suggest the surface has somehow torn to reveal darker materials from below.
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- Summary by Intellect · source: Europa, Jupiter's Second Moon: We Absolutely Must Get There!
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