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DannyB writes:

Keeping Our Sense of Direction: Dealing With a Dead Sensor

As the season has turned to winter in Jezero Crater, conditions have become increasingly challenging for Ingenuity, which was designed for a short flight-test campaign during the much warmer Martian spring. [...] In its new winter operations paradigm, Ingenuity is effectively shutting down during the night, letting its internal temperature drop to about minus 112 degrees Fahrenheit (minus 80 degrees Celsius) and letting the onboard electronics reset. This new way of operating carries with it risks to Ingenuity's electronic components, many of which are not designed to survive the temperatures they are being exposed to at night. Moreover, extreme temperature cycles between daytime and nighttime tend to cause stresses that can result in component failure.

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. A nonworking navigation sensor sounds like a big deal – and it is – but it's not necessarily an end to our flying at Mars.

[...] The inclinometer consists of two accelerometers, whose sole purpose is to measure gravity prior to spin-up and takeoff; the direction of the sensed gravity is used to determine how Ingenuity is oriented relative to the downward direction. 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.

[...] 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.

Taking advantage of this redundancy requires a patch to Ingenuity's flight software. The patch inserts a small code snippet into the software running on Ingenuity's flight computer, intercepting incoming garbage packets from the inclinometer and injecting replacement packets constructed from IMU data. To the navigation algorithms, everything will look as before [...]

A helicopter on Mars must necessarily experience harsher conditions than would a helicopter on the moon.

Original Submission