NASA's Mars helicopter's navigation sensor has stopped functioning, but that's not the end

NASA's Ingenuity Mars helicopter is dealing with a dead sensor, but it's not necessarily an end to the tiny rotorcraft's mission on the Red Planet. The helicopter requires a software patch that will allow it to resume flying, the agency said in a blog post earlier this week.

"Over the past several sols on Mars, the Ingenuity team has been busy recommissioning the helicopter for flight, going through a series of activities that include preflight checkout of sensors and actuators and a high-speed spin of the rotor. These activities have revealed that one of the helicopter's navigation sensors, called the inclinometer, has stopped functioning," Havard Grip, Ingenuity Mars Helicopter Chief Pilot at NASA's Jet Propulsion Laboratory, wrote in a blog post.

The flight control system onboard Ingenuity uses a sensor suite, consisting of an inertial measurement unit (IMU), a laser rangefinder and a navigation camera, to keep close track of current position, velocity, and orientation.

According to NASA, the data from these sensors is processed by a set of algorithms implemented on Ingenuity's navigation computer. For the algorithms to function properly, they must be initialized prior to takeoff with an estimate of the helicopter's roll and pitch attitude. This is where the inclinometer comes in.

The inclinometer is not used during the flight itself, but without it, we are forced to find a new way to initialize the navigation algorithms prior to takeoff, Grip noted.

Just like the accelerometers within the inclinometer, IMU contains accelerometers, which can be used to estimate the initial attitude. But the IMU is not purpose-built for sensing static orientation, so its initial attitude estimates will generally be somewhat less accurate. However, we believe an IMU-based initial attitude estimate will allow us to take off safely and thus provides an acceptable fallback that will allow Ingenuity to resume flying, he added.