Do scientists think water, lakes and rivers covered ancient Mars?”
Some clay fragments analyzed by the Mars probe Phoenix indicated molecules that are commonly formed in liquid water under tremendous pressure. The best explanation for this is that they were formed at the bottom of some kind of liquid water ocean or sea on Mars, but there could be other explanations. This could have been billions of years ago while the planets were still forming. Or after they formed, but before animal life populated Earth. No signs of life have been found yet, but this discovery increases the chances that life as we know it once existed on Mars, if in the deep past. Phoenix has also discovered water ice below the surface of Mars and analyzed very small fragments of it. It does not need very much for analysis. It scoops up a few grams, and analyzes only a few micrograms. It has been sending back information since it landed weeks ago. You can find out more information at the link below. I hope this helps.
