Future space helicopters may benefit as NASA completes history's first interplanetary aircraft crash inquiry. The yet-to-be-released technical report explains why the space agency's Ingenuity Mars helicopter crashed on January 18, 2024.
Part of NASA's Mars 2020 mission, Ingenuity is a classic example of overengineering paying off unexpected dividends. Carried to the surface of the Red Planet by the nuclear-powered Perseverance rover, its job was a very modest one – demonstrating that it was possible to build a helicopter that could fly on Mars. But it became much more than that.
When it made its first flight on April 19, 2021, the helicopter was only supposed to take off five times over the course of 30 Martian days. It went well beyond that, making 72 flights lasting a total of over two hours in three Earth years before it pranged into the desert sands on its last outing. In the meantime, it went from a technology demonstrator to becoming a valuable part of the Perseverance mission, by acting as a reconnaissance platform seeking out new places for the rover to visit.
The question remained, what happened to Ingenuity? Why did the scrappy 4-lb (1.8-kg) copter crash? Fortunately, the Mars mission was designed by NASA to send back an insane amount of data not only about the planet, but also about the vehicles themselves. Between telemetry and images captured, NASA engineers were able to piece together the unfortunate events of that day.
What they discovered was that on its last short flight, Ingenuity quickly reached an altitude of 40 ft (12 m) where it hovered and snapped pictures for later analysis. It began to descend just 19 seconds after takeoff and hit the ground at the 32-second mark, cutting off communications with Earth until Mission Control reestablished the link the next day.
Six days later, Perseverance relayed images to Earth, giving engineers more evidence about what happened.
What happened was that Ingenuity's rotors were smashed, permanently grounding the vehicle.
It's taken nearly a year to find the answers, which isn't surprising when you consider that the accident investigation team at the Jet Propulsion Laboratory (JPL) in Pasadena, California was 100 million miles away from the scene. They found that the crash was caused by Ingenuity operating outside of the conditions in which it was designed for navigating.
Ingenuity was designed to navigate by tracking visual features on the ground. That ground was the pebbly landscape near the landing site. On the last flight, the ground was much more flat, sandy, and covered with ripples.
This meant that the helicopter's systems couldn't track properly and couldn't estimate its descent speed. It hit one of the ripples hard and at an angle, causing Ingenuity to pitch and roll. This put heavy stresses on the rotors, snapping off all four of them and tearing one away so violently that there was a power surge which knocked out communications.
"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 JPL. "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."
According to NASA, the findings from the investigation will be useful for future interplanetary helicopter missions being planned in the wake of Ingenuity's success. One is a larger, dedicated copter mission for exploring Mars over a far larger area than a rover can manage. That one is in the concept stage, but a wilder one has been green-lighted to send a rotorcraft to explore Saturn's largest moon, Titan.
Meanwhile, Ingenuity is still making a valuable contribution to science. As a weather station.
Source: NASA