In February 2021, NASA's Perseverance rover landed on Mars. Tucked underneath it was a passenger: a tiny helicopter called Ingenuity. It weighed only about 1.8 kilograms, a little less than a big bag of flour.
Flying on Mars is much harder than flying on Earth. The air on Mars is extremely thin, about one hundredth as thick as the air we breathe. Helicopter blades push against the air to lift off, so with so little air, Ingenuity's blades had to spin very fast: about 2,400 times a minute.
On 19 April 2021, Ingenuity rose about three metres into the Martian sky, hovered for about forty seconds and landed again. It was the first powered, controlled flight on another planet. Engineers on Earth cheered, even though the radio signals took several minutes to reach them.
Ingenuity was only meant to make five test flights. Instead, it made 72. It scouted ahead for the rover, taking photos of rocks and slopes so that drivers on Earth could choose safe routes.
In January 2024, one of Ingenuity's blades was damaged during a landing, and the mission ended. The little helicopter still sits on Mars today, and engineers are already using what they learned to design bigger flying machines for future missions.
