Engineers are already beginning to plan for possible follow-on missions.
NASA’s Ingenuity Mars Helicopter, right, stands near the apex of a sand ripple in an image taken by Perseverance on Feb. 24, 2024, about five weeks after the rotorcraft’s final flight. Credit: NASA/JPL-Caltech/LANL/CNES/CNRS
Eleven months after the Ingenuity helicopter made its final flight on Mars, engineers and scientists at NASA and a private company that helped build the flying vehicle said they have identified what probably caused it to crash on the surface of Mars.
In short, the helicopter's on-board navigation sensors were unable to discern enough features in the relatively smooth surface of Mars to determine its position, so when it touched down, it did so moving horizontally. This caused the vehicle to tumble, snapping off all four of the helicopter's blades.
Delving into the root cause
It is not easy to conduct a forensic analysis like this on Mars, which is typically about 100 million miles from Earth. Ingenuity carried no black box on board, so investigators have had to piece together their findings from limited data and imagery.
"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," said Ingenuity’s first pilot, Håvard Grip of NASA's Jet Propulsion Laboratory, in a news release.
A team from NASA and a company that specializes in unmanned aerial vehicles, AeroVironment, started by looking at the terrain where Ingenuity was operating over during its 72nd flight, on January 18 of this year. The helicopter’s navigation system tracked visual features on the surface using a downward-looking camera. During its initial flights, Ingenuity was able to discern pebbles and other features to determine its position. But nearly three years later, Ingenuity was flying in a region of Jezero Crater filled with steep, relatively featureless sand ripples.
The navigation system uses these visual cues to help determine the vehicle's velocity and ensure that it returns to the surface with almost no lateral or vertical motion, to make a soft touchdown. About 20 seconds into the final flight, according to data from the vehicle, the navigation system was unable to lock on to features for sufficient positioning and velocity data.
Still talking, for now
As a result, when Ingenuity touched down, it had a horizontal velocity that caused it to make a hard impact and pitch and roll. One of the blades was ripped wholly off—instead of being sheared part way up the blade—draining the vehicle's power and leading to a loss of communications.
Amazingly, the vehicle was able to recharge somewhat with its solar panels and is continuing to communicate about once a week with the Perseverance rover that brought it to Mars in February 2021. This will last a little while longer before the rover and helicopter lose line-of-sight communications.
The remarkable success of Ingenuity has prompted NASA engineers to already begin planning for possible follow-on missions, including a larger "Mars Chopper" that could carry scientific instruments to study areas inaccessible to rovers.