Images of Europa from the Galileo spacecraft reveal a complicated terrain of grooved linear ridges and crustal plates which seem to have broken apart and rafted into new positions. That could indicate subsurface water or slush. In the image above, blue tints represent relatively old ice surfaces while reddish regions may contain material from more recent internal geological activity.
The quote above is specifically referring to an image on the page from which I took the quote:
There's a near-vertical line in the terrain, starting at ~0:58 on the right hand side, and continuing through the remainder of the video. If that was in a game, I'd suspect a texturing or geometry problem (this is a small evidence that we live in a simulation).
More seriously though, the linear features on the surface seem highly unusual; I wonder what's the geological explanation for them? EDIT: reading through other comments; apparently it's water freezing in cracks in the ice.
Above. It's icy, wherever the ice cracks the new water goes through the crack, then freezes and as it takes more space than when fluid there is the protruding line.
The colors are a reconstruction. As far as I remember, no camera on Galileo had a set of color filters that would approximate human vision. They each had a set of selectable color filters on a wheel, which had very narrow spectral ranges, some even outside the human visual range. These filters were selected for scientific reasons (e.g. exploit spectral bands where certain materials have a particularly low or high reflectivity to help identify them). Any color images you see from this and similar missions are reconstructions: a full color image would need to be taken with the whole spectrum from about 400nm to 700nm, which is much wider than the color filers that are available. So what you see is based on some kind of reconstruction of the parts of the visual spectrum that is missing in the source data.
I do not know how far you can take the reconstruction in practice. If you know the source illumination (it's the sun - easy), identify all the materials that are in the images successfully (hard) and know their reflection spectra (possible), you can in theory create realistic color impressions.
I've always wondered this same thing ever since I was fascinated as a child by the lurid green photographs of Ganymede (Jupiter) and Enceladus (Saturn) from Voyager 2, only to later discover that they're false color images.
blue-white terrains indicate relatively pure water ice, whereas the reddish areas contain water ice mixed with hydrated salts, potentially magnesium sulfate or sulfuric acid.
New ice. It’s believed Europa has a subsurface liquid ocean. Tidal flexing from Jupiter causes the surface ice to crack and water wells up from the lower ocean and refreezes.
Images of Europa from the Galileo spacecraft reveal a complicated terrain of grooved linear ridges and crustal plates which seem to have broken apart and rafted into new positions. That could indicate subsurface water or slush. In the image above, blue tints represent relatively old ice surfaces while reddish regions may contain material from more recent internal geological activity.
The quote above is specifically referring to an image on the page from which I took the quote:
https://science.nasa.gov/science-news/science-at-nasa/1998/a...
But I believe the stills which comprise the video fit the same overall description.
The mission page is https://solarsystem.nasa.gov/missions/galileo/in-depth/
And I think the images can be found at https://pds-imaging.jpl.nasa.gov/volumes/galileo.html