The car-sized Curiosity rover has spotted evidence of once quite hospitable environs on Mars. As shown in the imagery below, the NASA robot investigated dried-up lake beds and captured views of ripple formations on their ancient shorelines.

Caltech scientists published a study using NASA Curiosity rover imagery showing the past existence of warm water on Mars.

NASA has found signs of a lake on Mars, with evidence suggesting the presence of water rather than just ice. Researchers discovered ripples in the sandy shores of ancient lakebeds on Mars, which were likely created by the movement of water pushed by wind.