The car-sized Curiosity rover has spotted evidence of once quite hospitable environs on Mars.

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

On Jan. 25, 2004, NASA’s Opportunity rover landed on Mars and sent its first pictures of the planet to Earth; originally planned as a 90-day mission, the rover remained operational for over 15 years, travelling a total of 28 miles across the planet’s surface.

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.