Europa, a frozen moon around Jupiter, is believed to be one of the most habitable worlds in the solar system. It was first imaged in detail by the Voyager 1 probe in 1979, revealing a surface almost devoid of large craters. This suggested that water regularly floods up from inside, resurfacing the satellite. Europa is also criss-crossed with long troughs, folds and ridges, potentially made of icebergs floating around in melt-water or slush.
Source:
https://phys.org/news/2019-06-life-jupiter-moon-europa-discovery.html