Earlier this year, the NASA helicopter Ingenuity came to the end of its mission after an incredible 72 flights on Mars. The helicopter flew a remarkable 30 times farther than planned, and was the first rotocopter to fly on another planet, proving that exploring distant worlds from the air is possible. Now, NASA has revealed new details about what exactly caused the crash that brought the mission to an end, and what it learned about flying helicopters for future missions.

The final flight of Ingenuity took place on January 18, 2024, when the helicopter rose briefly into the air in a maneuver called a hop. The helicopter was fitted with a number of cameras, and shadows cast onto the planet’s surface revealed that one of the helicopter’s rotor blades was missing, having apparently separated at the mast. But it wasn’t certain what had caused this damage.

“When running an accident investigation from 100 million miles away, you don’t have any black boxes or eyewitnesses,” said Ingenuity’s first pilot, Håvard Grip of NASA’s Jet Propulsion Laboratory. “While multiple scenarios are viable with the available data, we have one we believe is most likely: Lack of surface texture gave the navigation system too little information to work with.”

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The problem seems to be, ironically enough, that the ground beneath the helicopter was too smooth and featureless. The helicopter had to be able to maneuver itself autonomously, due to the communications lag between Earth and Mars, so it used data from a downward-facing camera to track its movement across the surface. With no features on the surface during this particular flight, the helicopter’s computer could not accurately track its velocity, and it landed too hard, which caused the damage.

Further investigation found that the likely problem was that Ingenuity hit the surface too hard, then pitched to one side and rolled over. That meant weight was put onto the very light and delicate rotor blades, causing all four of them to snap at the tips. That created vibrations in the system, which ripped one blade off its mast completely.

This means Ingenuity can no longer fly, but it does still transmit data about weather conditions to the nearby Perseverance rover once per week. That’s impressive considering its electronics were fairly basic.

“Because Ingenuity was designed to be affordable while demanding huge amounts of computer power, we became the first mission to fly commercial off-the-shelf cellphone processors in deep space,” said Teddy Tzanetos, Ingenuity’s project manager. “We’re now approaching four years of continuous operations, suggesting that not everything needs to be bigger, heavier, and radiation-hardened to work in the harsh Martian environment.”

The Ingenuity mission was such a considerable success that NASA is already planning more rotorcraft missions in the future. One idea is for another Mars helicopter to be used as part of the Mars Sample Return program, which would be larger and heavier than Ingenuity and could carry science equipment in its explorations.

“Ingenuity has given us the confidence and data to envision the future of flight at Mars,” Tzanetos said.