How a planet’s plate techtonics form its shape - BBC

In 2022, NASA's Juno spacecraft flew by Europa and photographed a world crisscrossed with mysterious red lines. Grand canyons. Some 100 metres deep and tens of kilometres wide. In places coated in a red substance that may be a newly discovered compound of salt and water. Juno is the latest NASA mission to fly by Europa and take detailed photographs of its peculiar fractured surface. The canyons on Europa are quite unlike anything seen on Earth, or indeed anywhere in the entire solar system. The markings are geometric. They form lines that crisscross over the surface. So what can be causing that? Europa's surface features are an active area of research, taking NASA scientists to the frozen reaches of our own planet in search of answers. This is an image of a region on Europa's surface called Phaedra Linea. And see this feature? It almost looks like the Grand Canyon on Earth. It's actually about 50 kilometres across. A clue to what this is can be seen that if you look at the top line and the bottom line and just in your mind's eye just draw these together, you'll see that they knit together perfectly. So this looks like the crust has just spread. Now there's only one other place in the solar system where we see features like this and it's here on Earth. It's caused by plate tectonics. On Earth, it's the internal heat of the planet as it forces its way through the crust, which is the driving force of plate tectonics. No-one expected to see behaviour like this on a moon. On Europa, it's not molten rock that's driving its plates apart. Density measurements of the moon suggest that beneath the thick icy crust lies a different liquid. A global subsurface ocean of water. Up to 150 kilometres deep, it may contain two or three times all the water in Earth's oceans combined.