TRUNDLING across the surface of Mars one day in 2005, NASA’s geologist-robot. Opportunity, came across a rock composed mainly of iron and nickel. It was a meteorite, the first ever discovered on a planet other than Earth. Opportunity and its twin, Spirit, went on to discover many more meteorites and other curiosities on Mars, including minerals that are associated with liquid water.

Opportunity and Spirit were landed on opposite sides of the red planet in 2004, six weeks apart. Their mission was to find out whether water flowed on Mars in ancient times. Flowing at leaves its mark on the soul, clay and rocks. The robots found plenty of evidence to suggest that water once existed on the surface of Mars, creating on environment that could have sustained microbial life, if not higher life forms.

Scientists had expected the rovers to survive just 90 days or so on Mars, as they believed that dust would soon cover their solar panels, cutting off their energy supply. The scientists did not take into account the winds on Mars. The winds blew away the dust that settled on the penels and the rover-robots functioned for years instead of the expected there month.

Spirit sent its last message to Earth in March 2010, and Opportunity packed up only in January 2019. Besides peering into the soil and rocks, the robots also took thousands of photographs of the landscape and the skies, enabling us to see some amazing pictures, including Earth-like clouds scutting across the Martian skies.