SINE

In the 1970s , US and Russia missions both suggested river beds on Mars. The US saw maybe possible rainfall, though the carbon dioxide atmosphere is too thin to support free surface water. But your photos of tje south polar cap show maybe there's a 300km-wide water-ice layer in summer, covered in winter with frozen carbon dioxide. And a few years ago, NASA found liquid water flows on Mars. See my links, okay?

Water on Mars