During its sixth flight on Mars, NASA’s Ingenuity helicopter experienced a glitch that caused it to start tilting back and forth during the latter part of its flight. Though the helicopter’s performance was degraded by this, according to NASA, Ingenuity managed to survive the anomaly to ultimately land safely back on the Martian surface.
Ingenuity has successfully completed six flights on Mars, though the most recent flight didn’t proceed without issue. According to NASA, the helicopter made it about 150 meters into its flight before it started tilting back and forth, resulting in an oscillating pattern. The rest of the flight was completed, but Ingenuity spent it performing this rocking motion.
NASA’s ground team received a number of sensor indications before the helicopter landed, including ones indicating that the helicopter was experiencing power spikes and more. The space agency explains that Ingenuity features a navigation system and an inertial measurement unit (IMU) that estimate’s the vehicle’s position and speed, tweaking the control inputs as necessary for the helicopter to fly.
Ingenuity doesn’t depend on the IMU alone, however, due to the inevitability of eventual errors that would eventually cause the helicopter to ‘lose its way,’ as NASA says. To deal with that, navigation cameras facing downward snap images at 30fps and send them to the helicopter’s navigation system. An algorithm uses these to analyze the image data and regularly corrects the IMU estimates to precisely control things like velocity, the helicopter’s position, and its altitude.
The problem observed during Ingenuity’s last flight was due to a single image from the cameras being lost, which caused all of the images after it to have the wrong timestamp, NASA explains. This resulted in the navigation algorithm adjusting the IMU estimates ‘constantly’ using images that didn’t accurately represent the helicopter’s actual position and speed, resulting in the oscillations the vehicle experienced.
Fortunately, NASA’s team designed Ingenuity to withstand a certain degree of errors and instability without failing. As a result, the sixth flight was still ultimately a success, with Ingenuity landing within feet of its target location.